Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
KINETICS AND MECHANISM OF OXIDATION OF SOME
CHROMIUM(III) COMPLEXES BY PERIODATE ION
A thesis submitted to University of Khartoum
For
The degree of Doctor of Philosophy in Chemistry
by
ISMAT HASSAN ALI
(B.Sc. & M.Sc.)
Faculty of Science
University of Khartoum
SUPERVISOR: PROFESSOR YOUSIF SULFAB AHMED
Department of Chemistry
Faculty of Science
University of Khartoum
Khartoum, Sudan
July 2012
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Declaration
To the Graduate College:
This thesis has not been submitted for a degree in any other University.
Ismat Hassan Ali
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Dedication
To my parents
and
all family members
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table of Contents
Acknowledgments …………………………...………………...….…….… [vii]
Abstract (English) ……………………………..…………………..…..…. [viii]
Abstract (Arabic) ………………………………………………....………... [xi]
1. Introduction …………………………………………………….………. [1]
1.1 Oxidation-reduction reactions ...………….…….……………………… [1]
1.1.1 Classification of redox reactions ………….……………………….. [2]
1.1.1.1 Outer sphere electron transfer …….……………………...… [2]
1.1.1.1.1 Frank-Condon principle ………..…………………... [3]
1.1.1.1.2
Marcus theory ……..…………………….. [3]
1.1.1.2 Inner sphere electron transfer …………...…………………….. [4]
1.1.1.2.1 The bridging ligand …………………………………... [7]
1.1.2 Characterization of mechanism ……….…………....………………... [9]
1.2 Periodate ion………………………………………...…..………………… [9]
1.3. Chromium ……………………………………………..………………… [12]
1.3.1. Chromium(VI) ……………………………………..………………... [12]
1.3.2. Chemistry of chromium(V) ………………………..………...……… [13]
i
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
1.3.3. Chemistry of chromium(III)… ……………………...………………. [14]
1.3.3.1. Electronic structure of chromium(III) complexes ..…………… [16]
1.3.4 Chromium(II)….…………………………………………..…………. [17]
1.3.4.1. Electronic structure of chromium(II) compounds ……………... [18]
1.3.5 Biological importance of chromium ……………………….…….. [19]
1.6 Objectives of the study ………………………………………………….... [20]
2. Literature review ………………………………………………………….... [21]
3. Materials and methods ……………………………………….……………... [25]
3.1 Chemicals and solutions …………………………………………….….… [25]
3.2 Preparation of complexes ……………………………………………….... [25]
3.2.1 Preparation of cis-diaquabis(1,10-phenanthroline)chromium(III) complex
……………....…………………………………………………………………. [25]
3.2.2 Preparation of trans-1,2 cyclohexanediaminetetraacetatochromate(III)[27]
3.2.3. Preparation of diethylenetriaminepentaacetatochromate(III) ….…..... [27]
3.3. Kinetic procedures ………………………………………………………... [28]
3.4. Determination of the order and rate constant of the reaction …………….. [29]
ii
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
3.5. Determination of thermodynamic parameters ……………………………. [29]
4. Results………………………………………………………………………[31]
4.A. [CrIII(phen)2(H2O)]3+ ………………………………………………...…. [31]
4.A.1. Characterization of the complex ….………………………………… [31]
4.A.2. Stoichiometry of the reaction….....…………………….…………….[31]
4.A.3. Oxidation product……...………………………………………….….[32]
4.A.4. Results of the kinetic study………….…………...…………………..[33]
4.A.4.1. Effect of variation of complex concentration on the rate of the
reaction……...…………………………………………………………………..[33]
4.A.4.2. Effect of periodate concentration on the rate of reaction…….…..[37]
4.A.4.2.1 Variation of [IO4?] at 20.0 oC….………………………………[37]
4.A.4.2.1.1. Variation of [IO4?] at pH = 2.51…………………….…….[38]
4.A.4.2.1.2. Variation of [IO4?] at pH = 2.70…………………………...[42]
4.A.4.2.1.3. Variation of [IO4?] at pH = 3.03…………………………...[46]
4.A.4.2.1.4. Variation of [IO4?] at pH = 3.26.……..…….……………...[52]
4.A.4.2.1.5. Variation of [IO4?] at pH = 3.65…..………..……………...[56]
4.A.4.2.2. Variation of [IO4?] at 25.0 oC……………………….….……..…….[62]
iii
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
4.A.4.2.2.1 Variation of [IO4?] at pH = 2.81………………….…………..…[62]
4.A.4.2.2.2 Variation of [IO4?] at pH = 3.03………………………………...[66]
4.A.4.2.2.3 Variation of [IO4?] at pH = 3.17………………………………...[70]
4.A.4.2.2.4 Variation of [IO4?] at pH = 3.45…...……………………………[77]
4.A.4.2.2.5 Variation of [IO4?] at pH = 3.74…...……………………………[81]
4.A.4.2.2.6 Variation of [IO4?] at pH = 4.39…...……………………………[86]
4.A.4.2.3. Variation of [IO4?] at 30.0 oC…….……..………….………………..[92]
4.A.4.2.3.1 Variation of [IO4?] at pH = 2.51…………………………………[93]
4.A.4.2.3.2. Variation of [IO4?] at pH = 2.70…...….….…..………..……..…[97]
4.A.4.2.3.3. Variation of [IO4?] at pH = 3.03…………....…………..……...[101]
4.A.4.2.3.4. Variation of [IO4?] at pH = 3.26………..……..………...……..[105]
4.A.4.2.3.5. Variation of [IO4?] at pH = 3.65………..………..…………….[109]
4.A.4.2.4. Variation of [IO4?] at 40.0 oC………...…………………………….[115]
4.A.4.2.4.1. Variation of [IO4?] at pH = 2.51…………………….………….[115]
4.A.4.2.4.2. Variation of [IO4?] at pH = 2.70…………………………...…...[118]
4.A.4.2.4.3. Variation of [IO4?] at pH = 3.03…...…………………………..[122]
iv
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
4.A.4.2.4.4. Variation of [IO4?] at pH = 3.26…...……………………..……[127]
4.A.4.2.4.5. Variation of [IO4?] at pH = 4.39……………………………….[130]
4.A.4.3. Thermodynamic parameters…………………………………….......[137]
4. B. [CrIIIcdta(H2O)]? complex……………...………………………………...[139]
4.B.1. Characterization of the complex………….…………….…………….[139]
4.B.1.1. U
V– vis absorption spectrum……….……………………...……[139]
4.B.1.2. The molar extinction coefficient…….………..……………..……[139]
4.B.2. Stoichiometry of the reaction……………..…………………………...[140]
4.B.3. Oxidation product……………………………………………………..[141]
4.B.4. Results of kinetic measurements……………...…………………...….[142]
4.B.4.1. Effect of variation of complex concentration on the rate of the
reaction……………………………………...………………………...……….[142]
4.B.4.2. Effect of IO4? concentrations.……..………...….…………………[146]
4.B.4.3. Effect of hydrogen ion concentration………...……………….…..[150]
4.B.4.4. Iodate effect……………………………………………………….[158]
4.B.4.5. Effect of temperature on the rate of the reaction………………….[160]
4. C. [CrIIIdtpa(H2O)]2- complex…………..…………….…………………….[164]
4.C.1. Characterization of the complex…………………………….………..[164]
4.C.2. Stoichiometry of the reaction…………………………………..……..[164]
v
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
4.C.3. Results of kinetic measurements………………………...………..….[165]
4.C.3.1. Effect of variation of complex concentration on the rate of the
reaction……………………………………….…………………………......…[166]
4.C.3.2. Effect of variation of [IO4?]…………………………………....…[170]
4.C.3.3. Effect of variation of hydrogen ion concentration…………….….[174]
4.C.3.4. Effect of temperature on the rate of the reaction…..………......…[183]
4.C.3.5. Iodate effect…..…………………………………………………..[187]
5. Discussion ……...……………………...…………………………………...[188]
5.1. [CrIII(phen)2(H2O)2]3+ complex ...………………………...…………….[188]
5.2. [CrIIIcdta(H2O)]? and [CrIIIdtpa(H2O)]2- complexes ...….………………[192]
6. References ...……………………………..…………………………………[198]
Appendices
Two published papers abstracted from this thesis entitled:
One-step Two–Electron Oxidation of cis-Diaquabis(1,10-phenanthroline)chromium(III) to
cis-Dioxobis(1,10-phenanthroline)chromium(V) by
Periodate in Aqueous Acidic
Solutions.
Concurrent two one-electron oxidation of chromium(III) complexes of trans-1,2cyclohexanediaminetetraacete(cdta)
and
ligands by periodate ion.
vi
diethylenetriaminepentaacetate(dtpa)
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Acknowledgements
Al-Hamdolil-lah, it is only the blessing of Allah, The Almighty and The Merciful,
who enabled me to present this research work.
It gives me a profound pleasure to offer my sincere thanks to my supervisor Prof.
Yousif Sulfab Ahmed for his kind supervision, encouragement, inspiring guidance,
personal interest, continuous efforts and kind attitude I received during all the
phases of my study.
I am grateful to the Department of Chemistry, Faculty of Science, University of
Khartoum for providing all the necessary facilities to conduct this research.
Thanks are due to Dr. Sahar Shamselddin for providing me many scientific papers
and also to Dr. Nasma D. Aljack for her useful observations.
I wish to express my thanks to my research fellows for their kind cooperation.
Finally I am also indebted to all my family, colleagues and friends for their moral
support and to all my well wishers for their help during my research work.
vii
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Abstract
The objectives of this study are to prepare, characterize and investigate the kinetics
of
oxidation
of
cis-[CrIII(phen)2(H2O)2]3+ (phen
[CrIIIcdta(H2O)]? (H4cdta
=
trans-1,2
=
1,10-phenanthroline),
cyclohexanediaminetetraacetic
acid,
[CrIIIdtpa(H2O)]2- (H5dtpa = diethylenetriaminepenta acetic acid) by periodate ion.
These complexes were prepared by the reported methods and characterized
spectrophotometrically by comparing their UV – visible spectra with those
reported and by determination of their molar absorptivities. Also i. r. spectroscopy
was used to confirm their structures.
The rate of each reaction was followed spectrophotometrically. A Shimadzu UVvisible 1800 spectrophotometer, equipped with a thermostated cell holder stable to
± 0.1oC, was used to follow the reactions at a wavelength where the complex has a
maximum absorbance and all other species have negligible absorbance. Pseudofirst order conditions were maintained in all runs by using a large excess of [IO4?]
over that of the complex.
The kinetics of oxidation of cis-[CrIII(phen)2(H2O)2]3+ by IO4? has been studied in
aqueous acidic solutions in the pH range 2.51 – 4.39. In the presence of a vast
excess of [IO4?], the reaction is first order in the chromium(III) complex
concentration. The pseudo first-order rate constant, kobs, showed a very small
viii
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
change with increasing [IO4?]. The dependence of kobs on [IO4?] is consistent with
eq. (i).
kobs = a[IO4? ]/(b + c [IO4?])
(i)
The pseudo-first-order rate constant, kobs, increased with increasing pH, indicating
that the hydroxo form of the chromium(III) complex is the reactive species. An
inner-sphere mechanism has been proposed for the oxidation process. The
thermodynamic activation parameters of the processes involved are also reported.
The kinetics of oxidation of [CrIIIcdta(H2O)]? and [CrIIIdtpa(H2O)]2- complexes by
periodate ion have been studied in aqueous solutions. The oxidation of both
complexes was carried out in the pH range 5.52 – 7.44 and 5.56 – 8.56 for the
[CrIIIcdta(H2O)]? and [CrIIIdtpa(H2O)]2- complexes respectively. It was found that
at the end of the oxidation reaction by IO4?, chromium(VI) was formed. The
reaction exhibited an uncommon second order dependence on [CrIIIL(H2O)]n (L =
cdta or dpta and n = -1 or -2 respectively) and a first order dependence on [IO4?]
as shown in eq. (ii). The third order rate constant, k3, varied with [H+] according to
eq. (iii).
Rate = k3[CrIIIL(H2O)n]2[IO4?]
(ii)
1/k3 = a + b[H+] + c[H+]2
(iii)
A mechanism in which simultaneous two one–electron transfer from two
[CrIIIL(OH)]n-1 ions to I(VII) is proposed. The two [CrIIIL(OH)]n-1 ions are bridged
to I(VII) via the hydroxo group. Periodate is known to undergo rapid substitution
ix
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
or expansion of its coordination number from four to six. The thermodynamic
activation parameters of the processes involved, for both complexes, are reported.
The relatively high negative values of ? S* for both complexes is in agreement
with the proposed mechanism in which two hydroxo species of each complex
associate with IO4? prior to electron transfer.
x
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
ΚΤΒ
ϟ
κΨϠ
ϣ
Ϊ
Ϩ
ϋ
ϲΛ
ϼΜ
ϟ
ϡ
ϭ
ή
Ϝ
ϟ
Ε
Ϊ
Ϙ
ό
ϣ
ξό
Α
Δ
ϴ
ϟ
ϭ
Δ
ϴ
ϛ
ή
Σ
Δ
γ
έ
Ω
ϭ
ή
ϴ
πΤΗ
ϰϟ
·
Δ
γ
έ
Ϊ
ϟ
ϩ
ά
ϫ
ϑΪ
Ϭ
Η
ˬ
ϲ
Ύ
Ϩ
Λ
˯
Ύ
Ϥ
ϟ
ϲ
Ύ
Ϩ
Λ
–
ϥή
Θ
Ϙ
ϣ
ϲϫ
Ε
Ϊ
Ϙ
ό
Ϥ
ϟ
ϩ
ά
ϫ
ϭ
Ζϳ
Ω
Ϯ
ϳ
Ϸ
ϕϮ
ϓ
ϥϮ
ϳ
Δ
τγ
Ϯ
Α
Ύ
Ϭ
Η
Ϊ
δϛ
ϲϘ
Ϡ
Τϟ
ϥΎ
δϜ
Ϭ
ϟ
ˬ
–
ϕϭ
ή
ϔ
ϣ
ˬ
cis-[CrIII(phen)2(H2O)2]3+ ϲΛ
ϼΜ
ϟ
ϡ
ϭ
ή
Ϝ
ϟ
Ϧϴ
ϟ
ϭ
ή
Μ
ϧ
Ύ
Ϩ
ϴ
ϓ
Ϧϴ
ϣ
Ϸ
ϲΛ
ϼΛ
Ϧϴ
Ϡ
ϴ
Μ
ϳ
Ϲ
ϲ
Ύ
Θ
Λ
ˬ
[CrIIIcdta(H2O)]? ϲΛ
ϼΜ
ϟ
ϡ
ϭ
ή
Ϝ
ϟ
ΕϼΧ
ϲϋΎ
Α
έ
Ϧϴ
ϣ
Ϸ
ϲ
Ύ
Θ
Λ
[CrIIIdtpa(H2O)]2- ϲΛ
ϼΜ
ϟ
ϡ
ϭ
ή
Ϝ
ϟ
ΕϼΧ
ϲγΎ
Ϥ
Χ
ϕή
τϟ
Δ
τγ
Ϯ
Α
Ύ
Ϭ
ϧ
Ϯ
Ϝ
Η
Ϊ
ϴ
ϛ
΄
Η
Ϣ
Η
ϭ
Δ
ϴ
Ϥ
Ϡ
ό
ϟ
ϊ
Ο
ή
Ϥ
ϟ
ϲϓ
Δ
ό
Β
Θ
Ϥ
ϟ
ϕή
τϟ
Ύ
Α
Ε
Ϊ
Ϙ
ό
Ϥ
ϟ
ϩ
ά
ϫ
Εή
πΣ
ϲϓ
Ω
Ϯ
ΟϮ
ϣ
Ϯ
ϫ
Ύ
ϣ
ϊ
ϣ
Ύ
Ϭ
Ϩ
ϣ
ϞϜ
ϟ
ϲ
ή
Ϥ
ϟ
ιΎ
μΘ
ϣ
ϻ
ϒϴ
σ
Δ
ϧ
έ
Ύ
Ϙ
Ϥ
Α
Ϛϟ
Ϋ
ϭ
Δ
ϴ
Ϯ
πϟ
Δ
ϴ
ϓ
Ύ
ϴ
τϤ
ϟ
ϒϴ
σ
ϡ
Ϊ
ΨΘ
γ
Ύ
Ϥ
ϛ
Ύ
Ϭ
Ϩ
ϣ
ϞϜ
ϟ
ϱέ
ϻϮ
Ϥ
ϟ
Δ
ϴ
λΎ
μΘ
ϣ
ϻ
Ϟϣ
Ύ
ό
ϣ
ΏΎ
δΤΑ
Ύ
πϳ
ϭ
Δ
ϴ
Ϥ
Ϡ
ό
ϟ
ϊ
Ο
ή
Ϥ
ϟ
νή
ϐ
ϟ
Ε
ά
ϟ
˯
ή
Ϥ
Τϟ
ΖΤΗ
Δ
ό
ηϷ
ιΎ
μΘ
ϣ
ϕϮ
ϓ
ϒϴ
τϟ
ιΎ
μΘ
ϣ
ί
Ύ
Ϭ
Ο
Δ
τγ
Ϯ
Α
ϩ
ϼϋ
Γ
έ
Ϯ
ϛ
ά
Ϥ
ϟ
Ε
Ϊ
Ϙ
ό
Ϥ
ϟ
Γ
Ϊ
δϛ
ΕϻΪ
ό
ϣ
Δ
ό
Α
Ύ
Θ
ϣ
ΖϤ
Η
ϲΟϮ
Ϥ
ϟ
ϝ
Ϯ
τϟ
Ϊ
Ϩ
ϋ
Γ
έ
ή
Τϟ
Δ
Οέ
Ω
ϲϓ
Ϣ
Ϝ
ΤΘ
ϟ
ί
Ύ
Ϭ
Ο
Ϫ
ό
ϣ
ϖΤϠ
Ϥ
ϟ
ϲ
ή
Ϥ
ϟ
- ϲΠϔ
δϨ
Β
ϟ
ϰϟ
ϭ
Ϸ
Δ
Β
Η
ή
ϟ
ϑϭ
ή
χ
ϲϠ
ϋ
Ζϳ
ή
Ο
ϲΘ
ϟ
Ώέ
Ύ
ΠΘ
ϟ
ϊ
ϴ
Ϥ
Ο
ϲϓ
υΎ
ϔ
Τϟ
Ϣ
Η
Ϊ
ϔ
ό
ϣ
ϞϜ
ϟ
ΐγΎ
Ϩ
Ϥ
ϟ
Δ
Β
δϨ
ϟ
ΐδΣ
ϰϠ
ϋ
Ϊ
Ϙ
ό
Ϥ
ϟ
ΰ
ϴ
ϛ
ή
Η
Ϧϣ
ή
ϴ
Μ
Ϝ
Α
ή
Β
ϛ
Ζϳ
Ω
Ϯ
ϳ
Ϸ
ϕϮ
ϓ
ϥϮ
ϳ
ΰ
ϴ
ϛ
ή
Η
ϥΎ
ϛ
Κϴ
Σ
Δ
Α
Ϋ
Ύ
Ϝ
ϟ
Ύ
Ϥ
Ϭ
Ϩ
ϴ
Α
Δ
ϴ
ϟ
Ϯ
Ϥ
ϟ
ϲΛ
ϼΜ
ϟ
ϡ
ϭ
ή
Ϝ
ϟ
Ϧϴ
ϟ
ϭ
ή
Μ
ϧ
Ύ
Ϩ
ϴ
ϓ
ˬ
ϲ
Ύ
Ϩ
Λ
˯
Ύ
Ϥ
ϟ
ϲ
Ύ
Ϩ
Λ
–
ϥή
Θ
Ϙ
ϣ
Ϊ
Ϙ
ό
ϣ
Γ
Ϊ
δϛ
Δ
ϴ
ϛ
ή
Σ
Δ
γ
έ
Ω
ΖϤ
Η
xi
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
2.51- 4.39ϯΪ
Ϥ
ϟ
ϲϓ
ϲϨ
ϴ
Οϭ
έ
Ϊ
ϴ
Ϭ
ϟ
αϷ
Ϣ
ϴ
ϗ
Ζϧ
Ύ
ϛ
ϭ
Ζϳ
Ω
Ϯ
ϳ
Ϸ
ϕϮ
ϓ
ϥϮ
ϳ
Δ
τγ
Ϯ
Α
ϲγΎ
Ϥ
Ψϟ
ϡ
ϭ
ή
Ϝ
ϟ
Ϯ
ϫ
Ζϳ
Ω
Ϯ
ϳ
Ϸ
ϕϮ
ϓ
ϥϮ
ϳ
Δ
τγ
Ϯ
Α
Ϊ
Ϙ
ό
Ϥ
ϟ
Γ
Ϊ
δϛ
ΞΗ
Ύ
ϧ
ϥ
Δ
γ
έ
Ϊ
ϟ
ΖΤοϭ
ϝΪ
ό
ϣ
ΖΑ
Ύ
Λ
ϥ
Ξ
Ύ
Θ
Ϩ
ϟ
Εή
Ϭ
χ
Ϧϴ
Ϡ
ϋΎ
ϔ
Θ
Ϥ
ϟ
ϼϜ
ϟ
Δ
Β
δϨ
ϟ
Ύ
Α
ϰϟ
ϭ
Ϸ
Δ
ϴ
Η
ή
ϟ
ϊ
Β
Θ
ϳ
ϞϋΎ
ϔ
Θ
ϟ
ϥ
Ϊ
Οϭ
ΕΎ
Β
Λ
ϭ
Ζϳ
Ω
Ϯ
ϳ
Ϸ
ϕϮ
ϓ
ΰ
ϴ
ϛ
ή
Η
Ω
Ύ
ϳ
Ω
ί
ϊ
ϣ
Γ
ή
ϴ
ϐ
λ
Γ
έ
Ϯ
μΑ
Ω
Ω
ΰ
ϳ
ϱή
ϫ
Ύ
ψϟ
ϲϟ
ϭ
Ϸ
Δ
Β
Η
ή
ϟ
ϞϋΎ
ϔ
Η
Δ
ϟ
Ω
Ύ
ό
Ϥ
ϟ
Δ
τγ
Ϯ
Α
Ύ
Ϭ
Ϩ
ϋ
ή
ϴ
Β
ό
Θ
ϟ
ϦϜ
Ϥ
ϳ
Ύ
Ϥ
Ϭ
Θ
ϗ
ϼϋ
ϥ
Ϊ
Οϭ
ϭ
ϯή
ΧϷ
ϞϋΎ
ϔ
Θ
ϟ
Ϟϣ
Ϯ
ϋ
ϊ
ϴ
Ϥ
Ο
kobs = a[IO4?]/(b + c [IO4?]) Δ
Ϥ
ϴ
ϗ
Ω
Ύ
ϳ
Ω
ί
ϊ
ϣ
Ω
Ω
ΰ
ϳ
ϱή
ϫ
Ύ
ψϟ
ϲϟ
ϭ
Ϸ
Δ
Β
Η
ή
ϟ
Ϟ
ϋΎ
ϔ
Η
ϝΪ
ό
ϣ
ΖΑ
Ύ
Λ
ϥ
Ύ
πϳ
Ξ
Ύ
Θ
Ϩ
ϟ
ΖΤοϭ
ϥϮ
ϳ
Ϸ
Ϯ
ϫ
ϲΛ
ϼΜ
ϟ
ϡ
ϭ
ή
Ϝ
ϟ
Ϊ
Ϙ
ό
Ϥ
ϟ
ϲϠ
ϴ
δϛ
ϭ
έ
Ϊ
ϴ
Ϭ
ϟ
ϥϮ
ϳ
Ϸ
ϥ
ϰϠ
ϋ
ϝΪ
ϳ
ά
ϫ
ϭ
ϲϨ
ϴ
Οϭ
έ
Ϊ
ϴ
Ϭ
ϟ
αϷ
Ϟϣ
Ϯ
ό
ϟ
Ϣ
ϴ
ϗ
Ϊ
ϳ
Ϊ
ΤΗ
Ϣ
Η
Ύ
Ϥ
ϛ
ϲϠ
Χ
Ϊ
ϟ
ϝ
Ύ
ΠϤ
ϟ
Γ
Ϊ
δϛ
ωϮ
ϧ
Ϧϣ
ϞϋΎ
ϔ
Θ
Ϡ
ϟ
Δ
ϴ
ϟ
ΖΣή
Θ
ϗ
ςθϨ
ϟ
Ϣ
Η
ϲΘ
ϟ
Δ
ϴ
Ϡ
Ϥ
ό
ϟ
Ξ
Ύ
Θ
Ϩ
ϟ
ϊ
ϣ
ϖϓ
Ϯ
Θ
Η
ϞϋΎ
ϔ
Θ
Ϡ
ϟ
Δ
ϴ
ϟ
ΖΣή
Θ
ϗ
ϭ
ςϴ
θϨ
Θ
ϟ
Δ
ϟ
Ύ
Σ
Ϊ
Ϩ
ϋ
Δ
ϴ
Ϝ
ϴ
ϣ
Ύ
Ϩ
ϳ
Ω
Ϯ
ϣ
ή
ϴ
Μ
ϟ
Ύ
Ϭ
ϴ
ϟ
·
ϞλϮ
Θ
ϟ
ΕϼΧ
ϲϋΎ
Α
έ
Ϧϴ
ϣ
Ϸ
ϲ
Ύ
Θ
Λ
ϲϘ
Ϡ
Τϟ
ϥΎ
δϜ
Ϭ
ϟ
ˬ
–
ϕϭ
ή
ϔ
ϣ
ϱΪ
Ϙ
ό
ϣ
Γ
Ϊ
δϛ
Δ
ϴ
ϛ
ή
Σ
Δ
γ
έ
Ω
ΖϤ
Η
ϕϮ
ϓ
Δ
τγ
Ϯ
Α
ϲΛ
ϼΜ
ϟ
ϡ
ϭ
ή
Ϝ
ϟ
ΕϼΧ
ϲγΎ
Ϥ
Χ
Ϧϴ
ϣ
Ϸ
ϲΛ
ϼΛ
Ϧϴ
Ϡ
ϴ
Μ
ϳ
Ϲ
ϲ
Ύ
Ϩ
Λ
ϭ
ϲΛ
ϼΜ
ϟ
ϡ
ϭ
ή
Ϝ
ϟ
ϯΪ
Ϥ
ϟ
ϲϓ
Ϧϳ
Ϊ
Ϙ
ό
Ϥ
ϟ
Γ
Ϊ
δϛ
Δ
γ
έ
Ω
Ϊ
Ϩ
ϋ
ϲϨ
ϴ
Οϭ
έ
Ϊ
ϴ
Ϭ
ϟ
αϷ
Ϣ
ϴ
ϗ
Ζϧ
Ύ
ϛ
ϭ
ϲ
Ύ
ϣ
ςγϭ
ϲϓ
Ζϳ
Ω
Ϯ
ϳ
Ϸ
Δ
ϴ
ϧ
Ύ
Μ
ϟ
Δ
Β
Η
ή
ϟ
ϊ
Β
Θ
ϳ
ϞϋΎ
ϔ
Θ
ϟ
ϥ
Ξ
Ύ
Θ
Ϩ
ϟ
Εή
Ϭ
χ
ΐϴ
Η
ή
Θ
ϟ
ϰϠ
ϋ
-
ϭ
–
Ϊ
Οϭ
(2)
Δ
ϟ
Ω
Ύ
ό
Ϥ
ϟ
οϮ
Η
Ύ
Ϥ
ϛ
Ζϳ
Ω
Ϯ
ϳ
Ϸ
ϕϮ
ϓ
ϥϮ
ϳ
Ϸ
Δ
Β
δϨ
ϟ
Ύ
Α
ϰϟ
ϭ
Ϸ
Δ
Β
Η
ή
ϟ
ϭ
Ϧϳ
Ϊ
Ϙ
ό
Ϥ
Ϡ
ϟ
Δ
Β
δϨ
ϟ
Ύ
Α
3
Δ
ϟ
Ω
Ύ
ό
Ϥ
Ϡ
ϟ
Ύ
Ϙ
ϓ
ϭ
Ϧϴ
Οϭ
έ
Ϊ
ϴ
Ϭ
ϟ
ϥϮ
ϳ
ΰ
ϴ
ϛ
ή
Η
ή
ϴ
ϐ
Η
ϊ
ϣ
ή
ϴ
ϐ
Θ
ϳ
Δ
Μ
ϟ
Ύ
Μ
ϟ
Δ
Β
Η
ή
ϟ
ϞϋΎ
ϔ
Η
ϝΪ
ό
ϣ
ΖΑ
Ύ
Λ
ϥ
xii
k3[CrIIIL(H2O)n]2[IO4?]
ϝΪ
ό
Ϥ
ϟ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
3
1/k3 = a + b[H+] + c[H+]2
[CrIIIL(OH)]n-1
ϲϧ
Ϯ
ϳ
Ϧϣ
Δ
Ϩ
ϣ
ΰ
Θ
ϣ
Γ
έ
Ϯ
μΑ
Ϧϴ
ϧ
ϭ
ή
Θ
Ϝ
ϟ
ϝΎ
Ϙ
Θ
ϧ
ϦϤ
πΘ
Η
ϞϋΎ
ϔ
Θ
Ϡ
ϟ
Δ
ϴ
ϟ
ΖΣή
Θ
ϗ
Ϧϣ
ή
δΟ
Δ
τγ
Ϯ
Α
I(VII)
ϊ
ϣ
[CrIIIL(OH)]n-1
Ύ
ϧ
Ϯ
ϳ
ςΒ
Η
ή
ϳ
ϥ
Δ
ϴ
ϟ
ϵ
ϩ
Ϊ
ϫ
Ρή
Θ
Ϙ
Η
ϭ
I(VII)
ϰϟ
·
Δ
Β
ϟ
Ύ
δϟ
Δ
Ϥ
ϴ
Ϙ
ϟ
ςϴ
θϨ
Θ
ϟ
Δ
ϟ
Ύ
Σ
Ϊ
Ϩ
ϋ
Δ
ϴ
Ϝ
ϴ
ϣ
Ύ
Ϩ
ϳ
Ω
Ϯ
ϣ
ή
ϴ
Μ
ϟ
Ϟϣ
Ϯ
ό
ϟ
Ϣ
ϴ
ϗ
Ϊ
ϳ
Ϊ
ΤΗ
Ϣ
Η
Ϊ
ϴ
δϛ
ϭ
Ϊ
ϴ
Ϭ
ϟ
Δ
ϋϮ
Ϥ
Πϣ
ϲ
ΰ
ΟΩ
Ύ
ΤΗ
ϦϤ
πΘ
Η
ϲΘ
ϟ
ϭ
Δ
Σή
Θ
Ϙ
Ϥ
ϟ
Δ
ϴ
ϟ
ϵ
ϊ
ϣ
ϖϔ
Θ
Η
? S*
ςϴ
θϨ
Θ
ϟ
Ύ
ϴ
Α
ϭ
ή
Θ
ϧ
ϹΔ
ϴ
ϟ
Ύ
ό
ϟ
ϲϧ
ϭ
ή
Θ
Ϝ
ϟ
Ϲ
ϝΎ
Ϙ
Θ
ϧ
ϻ
ϞΒ
ϗ
Ζϳ
Ω
Ϯ
ϳ
Ϸ
ϕϮ
ϓ
ϊ
ϣ
Ϊ
Ϙ
ό
ϣ
Ϟϛ
Ϧϣ
Ϊ
ϴ
δϛ
ϭ
Ϊ
ϴ
ϫ
xiii
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Chapter(I)
1. Introduction
1.1 Oxidation-reduction reactions
Oxidation-reduction reactions of transition metal complexes, like all
redox reactions, involve the transfer of electron(s) from one species to
another, in this case, from one complex to another [1]. In oxidationreduction (redox) reactions of transition metal complexes, the
oxidation states of at least two reactants change. A net chemical
change does not necessarily occur as a result of a redox reaction [2].
The two molecules may be connected by a common ligand through
which the electron is transferred, in which case the reaction is called a
bridging or inner-sphere reaction, or the exchange may occur between
two separate coordination spheres in a nonbridging or outer-sphere
reaction [1].
The rates of reactions have been studied by many different methods,
including
chemical
analysis
of
the
products,
stopped-flow
spectrophotometry, and the use of radioactive and stable isotope
tracers. Taube's research group has been responsible for a large
amount of the data, and their reviews cover the field [1].
ϭ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
The rate of reaction for electron transfer depends on many factors,
including the rate of substitution in the coordination sphere of the
reactants, the match of energy levels of the two reactants, solvation of
the two reactants, and the nature of the ligands [1].
1.1.1 Classification of redox reactions
The most important single development in the understanding of the
mechanism of redox reactions has probably been the recognition and
establishment of outer-sphere and inner sphere processes.
1.1.1.1 Outer sphere electron transfer
In an outer-sphere mechanism, electron transfer occurs without a
covalent linkage being formed between the reactants [2]. When the
ligands of both reactants are tightly held and there is no change in their
coordination sphere, the reaction proceeds by outer-sphere electron
transfer. It involves intact (although not completely undisturbed)
coordination shells of the reactants [3].
Characteristically, the rates depend on the ability of the electrons to
tunnel through the ligands. This is a quantum mechanical property
Ϯ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
whereby electrons can pass through potential barriers that are too high
to permit ordinary transfer [1].
In outer-sphere reactions, where the ligands in the coordination sphere
do not change, the primary change on electron transfer is a change in
bond distance. A higher oxidation state on the metal leads to shorter s
bonds, with the extent of change depending on the electronic structure.
The changes in bond distance are larger when eg electrons are
involved, as in the change from high-spin Co(II) (t2g5 eg2) to low-spin
Co(III) (t2g6). Because the eg orbitals are antibonding, removal of
electrons from these orbitals results in a more stable compound and
shorter bond distances. Larger ligand field stabilization energy makes
oxidation easier. Comparing water and ammonia as ligands we can see
that the stronger field of ammonia makes oxidation of Co(II) relatively
easy [1].
1.1.1.1.1 Frank-Condon principle
According to Frank-Condon principle [4], there cannot be any
appreciable change of atomic arrangement during the time of electron
transition, as very light electrons move much more rapidly than the
much heavier atoms. This implies that motion of nuclei being slow
compared to that of electrons, electron transfer occurs without any
ϯ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
appreciable movement of nuclei. Interaction between [Fe(H2O)6]3+ and
[Fe(H2O)6]2+ forms the products in an energy rich state
[Fe(H2O)6]3+ + [Fe(H2O)6]2+ ?
[Fe*(H2O)6]2+ + [Fe*(H2O)6]3+
(1.1)
These energy rich ions lose their energy to the medium by colliding
with each other
[Fe*(H2O)6]3+ + [Fe*(H2O)6]2+ ? [Fe(H2O)6]3+ + [Fe(H2O)6]2+ + heat
(1.2)
It seems that the process described through eqs. (1.1) and (1.2) shows a
violation of the law of conservation of energy in that heat energy is
created in this reaction. For this pattern of interaction both ions can
rearrange to some intermediate position before the electron transfer
occurs. This requires energy from the solution, but an equivalent
amount of energy is released [5, 6], when the products revert to the
state as shown in eq. (1.2). Eqs. (1.1) and (1.2) demonstrate that
exothermic reactions are greatly favoured, in which the products are
formed in some suitably activated state to release the correct amount of
heat on thermal equilibrium [7].
1.1.1.1.2 Marcus theory
ϰ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Marcus received the Nobel Prize in 1993, in part, for proposing the
theoretical model for an outer-sphere electron transfer reaction [8-10].
In his model, he suggested that solvent molecules first orient
themselves to a configuration favourable for electron transfer around
the reactant ions, where the electron transfer occurs. This reorientation
of solvent molecules helps to attain the transition state structure
required for electron transfer. Reorganization of solvent structure
about each ion decreases the separation between two reactant ions. The
Marcus expression for the electron transfer rate constant is formulated
by considering the reaction (1.3), where ZA and ZB are charges on the
respective reactant ions and ? Z is the charge transferred.
AZA + BZB ? AZA+ ? Z + BZB- ? Z
(1.3)
The rate constant for the forward reaction can be expressed as,
kAB = ZAB e -? G*/RT
(1.4)
where ZAB is the collision frequency of uncharged species in solution
and is equal to kBT/h, kB is Boltzmann's constant. ? G*AB is the free
energy required to form the transition state from the reactants in their
equilibrium solvation configuration.
1.1.1.2 Inner sphere electron transfer
ϱ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
There are marked changes in the coordination spheres of the reactants
in the formation of the activated complex [11]. In this pathway two
metal ions get connected to form an activated complex through a
bridging ligand common to both co-ordination shells and reaction may
involve bond breaking and bond formation resulting in the actual
transfer of an atom or a ligand [12-14], as for example
[Cr(H2O)6]2+
+[Co(NH3)5Cl]2+
+
5H+
?
[Cr(H2O)5Cl]2+
+
[Co(H2O)6]2+ + 5NH4+ (1.5)
Aqueous chromium(II) is oxidized by [Co(NH3)5Cl]2+, and produces
the species [Cr(H2O)5Cl]2+. The Cl? ligand bridges the two metal
centers prior to the electron transfer step. The transition state is
represented by [(NH3)5Co-Cl-Cr(H2O)5]4+. This particular type of
reaction was reported for the first time by Taube and his coworkers
[13, 15].
The oxidation states of Co and Cr change from 3+ to 2+ and from 2+
to 3+ respectively. This shows that an electron was transferred from
Cr(II) to Co(III). This is subsequently followed by the transfer of the
(Cl?) ligand. This study was made through radio-isotope tracer
technique in which [Co(NH3)5Cl]2+ containing radioactive Cl? was
ϲ
4+
OH 2
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
dissolved in a solution containing Cr(II) and unlabelled Cl? [16]. After
reduction the product [Cr(H2O)5Cl]2+, was examined and was found to
contain only labeled Cl?. Both Cr(II) and Co(II) complexes are labile,
and Cr(III) and Co(III) are inert. This ligand transfer could be
visualized through the depiction given below which describes the
transfer of Cl?.
[Co(NH3)5Cl]2+
[Co(H2O)6]2+ +
+
5NH4+
[Cr(H2O)6]2+
+ [Cr(H2O)5Cl]2+
(1.6)
The following generalizations should be considered
for inner sphere, atom transfer or ligand transfer reactions.
1. In this mechanism, a molecule, atom or ion through which the
electron can route itself bridges the oxidant and reductant
together. One reactant (usually oxidant) possesses at least one
ligand capable of binding simultaneously the two metal ions.
ϳ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
2. The rate of inner-sphere reaction depends on the nature of
oxidizing and reducing agents. An inner-sphere activated
complex generally involves an inert reactant and a labile one.
But activated complexes involving both labile reactants have
also been reported to follow the inner-sphere mechanism [17].
3. Rate of atom transfer depends on the nature of the bridging
ligand. This has been manifested by studying the reduction of a
series
of
cobalt(III)
complexes
with
general
formula
[Co(NH3)5X]2+ with Cr(II) [13]. Using [Co(NH3)5X]2+ as an
oxidant, the transfer of X has been demonstrated to be a function
of the nature of X, a number of studies with X = C2H3O2?, Cl?,
Br? and SO42- have been reported[18]. It was found that the rate
of these reactions increased in the order C2H3O2? > SO42- > Cl? >
Br?.
4. Inner-sphere mechanism is preferred where large rearrangement
energy is required for the activated complex. The bridging
groups may reduce the Coulombic repulsions and facilitate a
good overlap between metal ions of the complexes. Thus
electron transfer is convened without close approach of charged
reactants. The total free energy for rearrangement gets reduced
ϴ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
and hence inner-sphere activated complex mechanism is
favoured. Organic ligands containing conjugated bond systems
act as mediators for electron transfer. The rate of electron
transfer is increased if the organic ligand is chelated with
reductant.
5. Transfer of a group or an atom in the inner-sphere mechanism
depends on the relative stabilities of the possible product. For
example, oxidation of chromium(II) occurs with [Ir(Cl)6]2complex, and produces the species [Cr(H2O)6]3+ and [Ir(Cl)6]3as shown below
[Cr(H2O)6]2+ + [Ir(Cl)6]2- ? [Cr(H2O)6]3+ + [Ir(Cl)6]3-
(1.7)
Although the possibility exists for chlorine atom transfer as in
the previous case shown in eq. (1.6), it doesn’t occur. This is
because the stability of
[Ir(Cl)6]3- is greater compared to
[Cr(H2O)5Cl]2+, whereas in the previous case, eq. (1.6) the
chromium(III) complex [Cr(H2O)5Cl]2+, is more stable than the
cobalt(II) complex [Co(H2O)6]2+.
6. The rate of a redox reaction increases when the metal ions
interact through the bridging group. This behaviour of atom
transfer facilitates the reaction as manifested in exchange
ϵ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
reaction between [Cr(H2O)6]2+ and [Cr(H2O)5Cl]2+ which is very
rapid. Contrary to that the reaction between [Cr(H2O)6]2+ and
[Cr(H2O)6]3+, where no bridging ligand is present, the rate is
much slower than the former [14].
Transfer of hydrogen atoms in reactions of aqua and hydrogen
complexes has also been studied and has been found to follow
inner-sphere mechanism [19-24].
1.1.1.2.1 The bridging ligand
The early work of Taube and his co-workers opened several interesting
avenues of approach. One of the most obvious is to examine the
requirements for a good bridging group and determine the effects of
this bridge on the rate of the inner-sphere redox reaction. Much data
have been obtained on reactions of the type
Cr(II) + [Co(NH3)5L]3+ + 5H+ ?
[CrL]3+ + Co(II) + 5NH4+
(1.8)
Oxidation by Cr(III) and Ru(III) also provides useful information, and
isotopic exchanges of the type in Eq. *1.9) that cannot be outer-sphere,
were explored early.
ϭϬ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
*Cr(II)
+
[Cr(III)X]2+
[*Cr(III)X]2+
+
Cr(II)
(1.9)
Investigations carried out about reactions (1.8) and (1.9) showed that
there is some general order of reactivity for various L ligands. An
unshared electron pair after coordination appears to be a minimum
requirement for a ligand to be a potential bridging group, for it has to
function as a Lewis base towards two metal cations. Thus
[Co(NH3)6]3+ and [Co(NH3)5py]3+, for example oxidize Cr(II) by an
outer-sphere mechanism, giving Cr(III) as the product, at a much
slower rate than for the inner-sphere reactions.
There is evidence, furthermore, that bridging electron transfer will not
occur even through an NH2 group in a ligand despite its having an
electron pair. There is no evidence of ligand transfer, and the rate
constants
are
small,
for
the
reactions
of
Cr(II)
with
Co(NH3)5OC(NH2)23+ and Co(NH3)5OCHNH3+ ions. The lone pair of
the nitrogen is apparently drawn into the O- C- N p system by the
[Co(NH3)5]3+ entity and is not available for attack by Cr(II).
The bridging group is often supplied by the oxidizing agent because
this is invariably the inert reactant. In these cases the bridging ligand
ϭϭ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
normally transfers from oxidant to reductant during the reaction. This,
however, is not an essential feature of an inner-sphere redox reaction.
The cyanide bridge is supplied by Fe(CN)64- in some reductions and
remains with the iron after electron transfer and breakup [2].
1.1.2 Characterization of mechanism
The characterization of a redox reaction as inner-sphere or outersphere is primarily a preoccupation of a kineticist. The assignment is
sometimes obvious, but often difficult and in certain cases impossible.
An inner sphere mechanism may be assigned via one or more of the
following:
a) From the nature of products.
b) By detection of a bridged species.
c) From rate data.
1.2 Periodate ion
Periodate ion is a two-electron oxidant in neutral and weakly acidic
solutions. Cyclic intermediates are often invoked in its reactions with
1, 2-diols [25]. Previously it was shown that IO4?, in most if not all its
reactions, with transition metal complexes and ions acts as an innersphere oxidant. This contention is based on the formation of
ϭϮ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
intermediate Co(III) products, as for example, in the oxidation of
Co(II) complexes with edta (edta = ethylenediaminetetraacetate), dtpa
(dtpa = diethylenetriaminepentaacetate), nta (nta = nitrilotriacetate)
and other polydentate ligands [26-28]. In some other cases the innersphere mechanism was proposed based on the form of the rate law [29,
30].
The many, sometimes complex, possible reaction pathways in
periodate ion oxidations, resulting from the various aqua species, are
probably responsible for the relatively limited work done on the
mechanism of its oxidation of inorganic metal complexes. Oxidation
reactions involving periodate ion and organic reductants have been
studied extensively and have been found to have large variations in
their rates with temperature and hydrogen ion activity [31-33]. These
variations can be explained by more detailed knowledge of periodate
species present in solution.
Periodate ion was found by Crouthamel et al. [34] to exist in various
degrees of hydration and protonaton in aqueous solution as shown by
the following equilibria.
H4IO6?(aq)
IO4?(aq) + 2H2O
KD
ϭϯ
(1.10)
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
H5IO6(aq)
H4IO6?(aq) + H+(aq)
H4IO6? (aq)
H3IO62- (aq) + H+(aq) K2
K1
(1.11)
(1.12)
The values of equilibrium constants agreed with earlier reported values
obtained from studies of dissociation of periodic acid [35]. At 25oC
and in the absence of added acid, the metaperiodate ion, IO4?,
predominates. There is evidence that in very concentrated acids e.g. 10
M HClO4, the ion I(OH)6+ is formed. The various pH-dependent
equilibria are established rapidly; kinetic studies of the hydration of
periodate IO4?, suggest either one-step or two step paths (Fig. 1.1), the
latter being more likely [36].
(A)
ϭϰ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
(B)
Fig.1.1 Schematic representation of (A) the one-step and (B) the twostep mechanism for aquation of IO4? to H4IO6?, dotted lines represent
hydrogen bonds.
The periodate ion dimerises at pH > 7 [37].
2IO4- +2OH-
H2I2O10ϰ-
(1.13)
Hence in an alkaline (i. e. OH?) medium, competition for the reductant
by metaperiodate and the dimeric form is to be expected. The extent of
dimerizaton and relative reactivity of the dimer and metaperiodate
species may be inferred from analysis of the kinetic data. At high
temperature and high pH the concentration of the dimer becomes
insignificant because the dimeric species is thermally unstable with
respect to the parent ion.
ϭϱ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
In the periodate oxidation of glycol [38] equilibrium equations (1.11)
and (1.12) were applied. The reaction is H+ and OH? dependent and
was postulated to go through an intermediate involving IO4? and glycol
adduct [39].
1.3 Chromium
The highest oxidation state of chromium is that corresponding to the
total loss of its 3d and 4s electrons. Chromium(VI), which exists only
in oxo species such as CrO3, CrO42- and CrO2F2, is strongly oxidizing.
Although chromium(V) and chromium(IV) are formed as transient
intermediates in the reduction of chromium(VI) solutions and until
recently, these oxidation states have no stable aqueous chemistry
except as peroxo complexes because of their ready disproportionation
to chromium(III) and chromium(VI). Some solid and gaseous
compounds do, however, exist. The most stable and important
oxidation state
of chromium is +3, d3, which in an octahedral
environment, has each orbital in the t2g level singly occupied, giving a
sort of half filled shell stability. The lower oxidation states are strongly
reducing; in aqueous solution only the divalent state, Cr(II), is known
[36].
ϭϲ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
1.3.1 Chromium(VI)
Complex formation by Cr(VI) requires strong p-donor ligands such as
O2- or (O2)2-[3]. Like other transition metals, notably, Ti, V, Ta, Nb,
Mo and W, chromium forms peroxo complexes in the higher oxidation
states. They are all more or less unstable; both in and out of solution,
decomposing slowly with the evolution of oxygen, and some of them
are explosive or flammable in air. The main ones are adducts of the
deep blue chromium peroxide, CrO5, the violet peroxochromates, the
red peroxochromates, and the addition compounds of CrO42- [36].
When H2O2 is added to an acidified solution of a chromium(VI) salt,
the product (formed as a solution species) is a deep violet-blue
complex which contains both oxo and peroxo ligands
(CrO4)2- + 2H+
+
2H2O2 ? [Cr(O)(O2)2] +
3H2O
(1.14)
In aqueous solution, [Cr(O)(O2)2] rapidly decomposes to Cr(III) and
O2. An ethereal solution is more stable and, from it, the pyridine
adduct [Cr(O)(O2)2(py)] may be isolated. In the solid state,
[Cr(O)(O2)2(py)] contains an approximate pentagonal pyramidal
arrangement of oxygen atoms with the oxo ligand in the apical site. If
each peroxo ligand is considered to occupy one rather than two
ϭϳ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
coordination sites, then the coordination environment is tetrahedral.
Chromium(VI) in acidic solution is a powerful oxidizing agent, albeit
often slow [3].
1.3.2 Chemistry of chromium(V)
Recently there has been a growing interest in the chemistry of
chromium(V). Chromium(V) is believed to be a transient species in the
reduction of chromium(VI) to chromium(III) [40-42]. This oxidation
state is also proposed in the oxidation of chromium(III) complexes to
chromium(VI) [43]. Chromium(V) complexes have been prepared by
several methods. These included: (i) the oxidation of chromium(III)
complexes [44-48], (ii) reduction of chromium(VI) in presence of
suitable ligands [49], (iii) intramolecular photo redox of chromium(III)
[50,51] and (iv) oxidation of chromium(0) species by air in presence of
suitable ligands [52].
Although a few reactive chromium(V) complexes are known, they
have been mostly isolated as rather weak polymeric or anionic
oxidants. The presence of oxo-chromium bond (i.e. O=Cr) is the most
common feature of the metal in this high oxidation state. However, the
chemistry associated with oxochromium(V) species is largely
O
O
v
Cr L +
C
C
C
C
ϭϴ
+ Cr
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
unexplored. The possibility of effecting a direct transfer of an oxygen
atom from the O=Cr functionality to a donor such as an olefin, e.g.
III
L
(1.15)
poses an interesting challenge, which has been realized with two
chromium(V) complexes. Groves and Kruper were the first to isolate a
reactive red species characterized as an oxochromium(V) derivative of
chloro(diphenylporphyrinato)
chromium(III)
by
treatment
with
iodosylbenzene [42]. Subsequently Kochi et. al presented a series of
active and well characterized oxochromium(V) cations derived from
N,N'-ethylenebis(salicylidineaminato)chromium(III)
hexaflourophosphates [44, 45].
1.3.3 Chemistry of chromium(III)
The +3 oxidation state is the most stable form of chromium in its
complexes and octahedral coordination dominates for chromium(III)
centres. It has a large ligand field stabilization energy (LFSE)
associated with the octahedral d3 configuration [3]. The principal
characteristic of these complexes in aqueous solution is their relative
kinetic inertness. Ligand displacement reactions of chromium(III)
ϭϵ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
complexes are only about 10 times faster than those of cobalt(III), with
half-lives in the range of several hours. It is largely because this kinetic
inertness many complex species can be isolated as solids and that they
persist for relatively long periods of time in solution, even under
conditions where they are thermodynamically quite unstable.
Ammonia and amine complexes are the most numerous chromium(III)
derivatives and the most extensively studied. They include the pure
amines, [CrAm6]3+, the mixed amine-aqua types, that is, [CrAm63+
n(H2O)n]
(n = 0 – 4, 6), the mixed ammine-acido complexes, that is,
[CrAm6-n(R)n](3-n)+ (n = 1 – 4, 6), and the mixed ammine – aqua – acido
types, for example [CrAm6-n-m(H2O)n(R)m](3-m)+ (n = 1 – 4, 6). In these
general formulae, Am represents the mono dentate ligand NH3 or half
of a poly dentate amine such as ethylenediamine, and R represents an
acido ligand such as a halide, nitro or sulfate ion. The preparation of
polyamine complexes sometimes presents difficulties in part due to the
fact that in neutral or basic solution hydroxo or oxo bridged poly
nuclear complexes are often formed. The oxo-bridged complex has a
linear Cr- O- Cr group, indicating dp- pp bonding as in other cases of
M- O- M groups. Anionic complexes are also common and are of the
type [CrX6]3- where X may be F?,Cl?, NCS?, CN?, but they may also
ϮϬ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
have lower charges if neutral ligands are present as in the ion
[CrIII(NCS)4(NH3)2]?. Complexes of bi- or poly-dentate ions are also
known; one example being [Cr(ox)3]3-. A different type of anionic
complex Cr2Cl93- which has three bridging Cl atoms and the Cr3+ ions
repel each other from the centres of their octahedra and the magnetic
moments are normal, indicating that there is no Cr- Cr bond. As
expected, Cr(III) can also form complexes of other types, including
neutral complexes with ß-diketonates and similar ligands, e.g.,
Cr(acac)3 (acac = acetylacetonate) and [Cr(OCOCF3)3]. It also forms
basic acetate compounds that have an unusual structure. The basic unit
is [Cr3O(CH3COO)6L3]+ in which there is an equilateral triangle of Cr
atoms with O atom at the centre. There are two bridging CH3COO?
groups across each edge of the triangle. Finally a molecule L, e.g.,
H2O, py, etc., is coordinated to each Cr so that it forms a distorted
octahedral coordination. This oxygen centered triangular structure
appears to be a characteristic feature of M(III) carboxylates and
possibly also of sulfates and certain chloro complexes. It is, moreover,
found for M(III) oxoacetates of Fe, Mn, V, Ru and possibly Co(III)
[36].
1.3.3.1 Electronic structure of Chromium(III) complexes
Ϯϭ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
From the simple orbital-splitting (Fig. 1.2), it follows that all such
complexes must have three unpaired electrons irrespective of the
strength of the ligand field, and this has been confirmed for all
mononuclear complexes. More sophisticated theory further predicts
that the magnetic moment should be very close, but slightly below the
spin only value 3.88 B. M.; this, too, is observed experimentally. The
spectra of Cr(III) complexes are also well understood in their main
features. A partial-energy level diagram is shown in Fig. 1.2.
d
1
d
2
d
3
Fig. 1.2. Orbital splitting of Cr(III)
It is seen that three spin-allowed transitions are expected, and this have
been observed in a considerable number of complexes. Indeed, the
spectrochemical series was originally established by Tsuchida using
data for Cr(III) and Co(III) complexes. In the aqua ion, the bands are
found at 14700, 24700 and 37000 cm-1.
1.3.4 Chromium(II)
ϮϮ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Aqueous solutions of Cr(II) ion, which is sky-blue in colour, are best
prepared by dissolving electrolytic Cr metal in dilute mineral acids, but
they can be prepared by reducing Cr(III) solutions by zinc amalgam or
electrolytically. The Cr(II) ion is readily oxidized
Cr3+ +e ? Cr2+ Eo = -0.41 V
(1.16)
and the solutions must be protected from air-even then, they
decompose at rate varying with acidity and the anions present, by
reducing water and liberation of hydrogen. The mechanisms of
reductions of other ions by Cr(II) have been extensively studied
especially by H. Taube and his co-workers, since the resulting Cr(III)
complex ions are substitution-inert. The products of oxidation of Cr(II)
depend on the nature of the oxidant. With one electron oxidants, the
ions [Cr(H2O)6]3+ or [Cr(H2O)5X]2+, where X is derived from the
oxidant, are the usual products. With two-electron oxidants there is a
possibility of oxidation by the route
Cr(II) - 2e ? Cr(IV)
(1.17)
Cr(II) + Cr(IV) ? 2Cr(III)
(1.18)
and in some cases it is known that intermediate species (possibly
binuclear) are formed [36].
Ϯϯ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Comparatively, few Cr(II) halide complexes are known. The halides
form adducts with ammonia e.g. CrCl2. nNH3 (n = 1-6) and with
nitriles, e.g., CrCl2. 2CH3CN, and with halogeno complex ions, KCrF3
and K2CrCl4 have also been obtained. Five coordinate complexes with
distorted trigonal-bipyramidal geometry are formed with several tripod
ligands, e.g., [Cr2(Me6tren)Br]+. Chromium(II) forms several dinuclear
species well characterized with quadruple interactions between metal
ions. Such a quadruple interaction between the two d4 metal ions
accounts for the diamagnetism of the compound. A number of other
essentially diamagnetic Cr(II) carboxylates are known and presumably
have the same dinuclear structure [36].
1.3.4.1 Electronic structure of chromium(II) compounds
In an octahedral environment two electron distributions t2g3eg and t2g4,
are possible. The magnetic data show that in general chromium(II)
compounds are of high-spin type and the moments are ~ 4.95 B. M.,
i.e., close to spin only value. An ion with d4 high-spin configuration
should cause Jahn-Teller distortion of an octahedral environment [36].
1.3.5 Biological importance of chromium
Ϯϰ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
The interest in chromium as a nutritional enhancement to glucose
metabolism can be traced back to the 1950s, when it was suggested
that brewer’s yeast contained a glucose tolerance factor (GTF) that
prevented diabetes in experimental animals. This factor was eventually
suggested to be a biologically active form of trivalent chromium that
could substantially lower plasma glucose levels in diabetic mice. The
results of these studies strongly implicated chromium as a critical
cofactor in the action of insulin. How chromium serves as a cofactor
for insulin action is not fully understood. From several in vivo and in
vitro studies, it was initially thought that chromium potentiated the
actions of insulin as part of an organic complex, GTF. More recent
studies have suggested that chromium may function as part of the
oligopeptide low–molecular weight chromium (LMWCr)-binding
substance which is composed of glycine, cysteine, glutamic acid, and
aspartic acid [53,54].
Ϯϱ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
1.6 Objectives of the study
The aims of this study are:
(i) To prepare and characterize the following complexes:
1. cis-[CrIII(phen)2(H2O)2](NO3)3.2.5H2O
(phen
=
1,
10-
phenanthroline).
2. [CrIIIcdta(H2O)]?
(cdta
=
trans-1,
2
cyclohexanediaminetetraacetate).
3. [CrIIIdtpa(H2O)]2- (dtpa = diethylenetriaminepentaacetate).
(ii) To study the kinetics of oxidation of these complexes by periodate
ion.
(iii) To investigate the effect of the following factors on the oxidation
rates
• Concentration of the reactants.
• Temperature.
• Ionic strength.
• pH.
(iv) To propose a reasonable mechanism for each reaction.
Ϯϲ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
(v) To calculate the thermodynamic parameters.
The reasons for choosing these complexes are:
• Chromium complexes are biologically important.
• The oxidations of these complexes by periodate ion have not
been studied kinetically.
Chapter (II)
2. Literature review
The observed second-order dependence on the reductant concentration
in IO4? oxidation was reported previously. The IO4? oxidation of both
[FeII(H2O)6]2+ and [CrIII(H2O)6]3+ seems to support an inner-sphere
mechanism. In these two reactions two one-electron transfer in a single
activated complex was proposed. Two one electron transfer processes
are believed to occur via an inner-sphere mechanism [55,56].
The kinetics of oxidation of cis-[CrIII(ox)2(H2O)2]?(ox = C2O42-) by
periodate ion was studied. It showed a first order dependence on
Ϯϳ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Cr(III) complex concentration. The dependence on periodate
concentration is complex and is consistent with the formation of a
precursor complex [43].
The kinetics of oxidation of the chromium(III)-guanosine 5monophosphate
complex,
[57],
chromium(III)-DL-valine
complex,[58], chromium(III)-DL- aspartic acid complex, [59], (both in
the presence of iron(II) as a catalyst), chromium(III)-L-glutamic acid
complex, [CrIIIL2(H2O)2]+, [60], and
[CrIII(HNTA)(Hist)(H2O)]?,
[CrIII(HNTA)(Asp)(H2O)] (NTA = nitrilotriacetate, Hist = Lhistidinate
and
Asp
[CrIII(HIDA)(Val)(H2O)2]+,
=
DL-aspartate)
[61],
[CrIII(HIDA)(Arg)(H2O)2]+
and
(HIDA
=
iminodiacetic acid, Val = DL-valine and Arg = L-arginine) [62], by
periodate
ion
in
aqueous
medium
has
been
studied
spectrophotometrically. The complexes gave different rate laws. It was
proposed that electron transfer proceeds through an inner-sphere
mechanism via coordination of IO4? to chromium(III). A common
mechanism for the oxidation of some chromium(III) complexes by
periodate was proposed. The choice of ternary complexes was
attributed to two considerations. Firstly, in order to study the effect of
the secondary ligands DL-valine and L-arginine on the stability of the
Ϯϴ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
binary
complex
[CrIII(HIDA)(IDA)(H2O)]
towards
oxidation.
Secondly, transition metal ternary complexes have received particular
focus and have been employed in mapping protein surfaces as probes
for biological redox centers and in protein capture for both purification
and study. The results have shown that the reaction is first order with
respect to both [IO4?] and the complex concentration, and the oxidation
rate increases with increasing pH in all cases.
The kinetics of oxidation of [CrIII(H2O)(TOH)], (TOH = N-(2hydroxyethyl)ethylenediamine-N,N',N'-triacetate)
[CrIII(H2O)(XOH)],
(XOH
[63],
=
and
N-(2-
hydroxycyclohexyl)ethylenediaminetriacetate) [64], to Cr(VI) by
periodate ion have been investigated in aqueous solution at various pH
values. It was found that the reaction is first order on both reactants
concentration and the electron transfer proceeds via an inner sphere
mechanism in which the hydroxo ligand on the chromium(III) complex
bridges the two reactants.
Kinetics of the oxidation of diaqua(nitrilotriacetato) chromium(III)
complex
by
N-bromosuccinimide
in
aqueous
solution
was
investigated. The electron transfer was proposed to proceed through an
inner-sphere mechanism [65].
Ϯϵ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
The kinetics of formation of chromium(III)–iminodiacetic acid
complex
by
N-bromosuccinimide
have
been
spectrophotometrically in the temperature range 35–55
studied
o
C. The
reaction is first order with respect to chromium(III) and the rate of
reaction increases with increasing of pH [66].
Chromium(III) octahedral complexes are generally inert to the
substitution of inner sphere water molecules by other ligands but some
reports
indicate,
however,
that
the
chromium(III)
complex,
aqua(ethylenediaminetetraacetate)chromium(III), with one molecule of
water and a five coordinate EDTA type ligand shows unexpectedly
rapid substitution rates with several anionic ligands. It has been
suggested that these reactions are due in part to strain present in the
complex [67].
The kinetics of the oxidation of [CrIII(HY)H2O], (Y = EDTA), by IO4?
to yield Cr(VI) was investigated. The reaction exhibited a first-order
dependence on each reactant concentration. The electron transfer was
proposed to proceed through an inner-sphere mechanism with the
hydroxo-ligand of the chromium(III) complex bridging the two
reactants [68].
ϯϬ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
The
kinetics
of
oxidation
CrIIINTMP,
nitrilotris(methylenephosphonato)chromium(III),
of
by
periodate ion to yield Cr(VI) has been studied spectrophotometrically
over the 5.80–6.85 pH range at 22–33 °C. The reaction rate is firstorder with respect to [CrIIINTMP] and [IO4?] and inversely dependent
on [H+]. The activation parameters were calculated from the
temperature dependence of the specific rate constants. A mechanism is
proposed in which the hydroxo complex, [CrHNTMP(OH)]3–, is the
reactive
species.
The
results
support
a
mechanism
where
intramolecular electron transfer is the rate-determining step [69].
The kinetics of oxidation of hypophosphitopentamminechromium(III)
complex by periodate ion was investigated as a function of the
temperature, ionic strength, and concentration of perchloric acid. The
reaction
rate
decreased
with
increasing
ionic
strength
and
concentration of perchloric acid. The redox reaction proper involving
transfer of an oxygen atom is preceded by dissociation of hydrogen
from the coordinated hypophosphite. The reactivity of the latter is
compared with that of the free hypophosphite [70].
ϯϭ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Periodate ion oxidation of iminodiaacetatochromium(III) complex was
studied in aqueous and acidic medium [71].
The oxidation kinetics of the 2-aminomethylpyridinechromium(III)
complex by periodate ion in aqueous solution was studied. An innersphere mechanism was proposed. The effect of Cu(II) on the oxidation
rate was studied over the (1.0 – 9.0) × 10- 5 M range. The reaction rate
was found to be inversely proportional to the Cu(II) concentration over
the range studied [72].
A
kinetic
study
of
the
oxidation
of
[CrIIIZ(H2O)]
(Z=N-
phenylethylethylenediaminetriacetate) by periodate ion, to produce
chromium(VI), was carried out in aqueous solutions. The reaction is
first order with respect to both total chromium(III) and total periodate
concentrations, and the rate is inversely dependent upon [H+] in the
5.43 – 7.02 pH range. The reaction may follow two-step inner-sphere
electron transfer mechanism. The activated parameters are reported.
Steric effects of the phenyl ring account for the smaller electrontransfer
rate
constants
for
[CrIIIZ(H2O)]
[CrIII(TOH)(H2O)],
compared
to
(TOH=N-(2-hydroxyethyl)
ethylenediaminetriacetate) [73].
Chapter (III)
ϯϮ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
3. Materials and methods
3.1 Chemicals and solutions.
The chemicals CrIII(NO)3.9H2O (BDH), H4cdta (GFS), H5dtpa (GFS),
NaH2PO4 (BDH), NaOH (BDH), NaNO3 (BDH) and NaIO4(99%)
(Aldrich) were used without further purification, edsta (disodium salt),
(Sigma), Sodium sluphate and sodium hydrogen sulphate were of
reagent grade (BDH). Potassium dichromate, nitric acid, acetic acid
and sodium acetate were of reagent grade (BDH) and were used
without further purification. Aqueous solutions of these chemicals
were prepared by accurate weight. Fresh redistilled water in the
presence of alkaline MnO4? solution in an all-glass distillation
apparatus was employed in all chemical preparations and experiments.
Solutions of NaIO4 were wrapped by aluminum foil to avoid
photochemical decomposition [74].
3.2 Preparation of complexes
3.2.1 Preparation of cis-diaquabis(1,10phenanthroline)chromium(III) complex
A
direct
preparation
of
the
cis-diaquabis(1,10-
phenanthroline)chromium(III) complex was carried out by refluxing
ϯϯ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
100 cm3 of a mixture of 0.01mole Cr(NO3)3.9H2O in 50 cm3 of water
and 0.022 mole of 1,10-phenanthroline in 50 cm3 of HNO3 (0.10 M)
for a period of 8 hours. Four aliquots of sodium hydroxide were added
to the reflux mixture to neutralize the hydrogen ions released at the
end of 1, 3, 5, and 7 hours. At the end of this period sufficient nitric
acid was added to lower the pH to 1; approximately one half of the
water was evaporated and upon cooling the salt crystallized out. The
crude product was recrystallized from 0.10 M nitric acid, washed with
0.10 M nitric acid and dried in a desiccator over sulphuric acid [75].
The
reddish-orange
product
has
the
formula;
[CrIII(phen)2(H2O)2](NO3)3.5/2H2O] and the ion of the complex has the
following structure;
3+
N
OH 2
N
N
Cr
N
N
N =
N
1,
OH 2
phenanthroline
ϯϰ
N
10-
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig.
2.1.
Structure
of
cis-diaquabis(1,10-
phenanthroline)chromium(III) complex.
The purity of the complex was determined spectrophotometrically in
0.10 M HNO3. The product of this reaction has been shown, even in
presence of excess oxidant concentration, to produce a relatively stable
[CrV(phen)2(O)2]+ [46 - 48]. It was found that at the end of the reaction
no chromium(VI) was formed by the sym-diphenylcarbazide test [76].
In a typical kinetic run acrylonitrile (Aldrich) was added to the
reaction mixture before addition of IO4?. Polymerization of
acrylonitrile was not observed. In a few runs LiClO4 was used to adjust
ionic strength instead of NaNO3.
3.2.2
Preparation
of
trans-1,
2
cyclohexanediaminetetraacetatochromate(III)
A solution of 1:1 Cr(III) : cdta gave a violet complex. Its absorption
spectrum exhibits two maxima at 395 nm and 540 nm. The complex is
not formed immediately. The absorbance did not reach its maximum
value even after a week at room temperature. When the temperature
was raised to 100 oC the complex was formed rapidly. The colour was
ϯϱ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
fully developed after 5 minutes of gentle boiling. The absorption
spectrum and molar absorbance are in agreement with those reported
[77]. The violet product has the formula; [CrIIIcdta(H2O)]?. It was
found that at the end of the oxidation reaction by IO4?, chromium(VI)
was formed by the sym-diphenylcarbazide test [76].
3.2.3 Preparation of diethylenetriaminepentaacetatochromate(III)
The two absorption bands of Cr(III) at 425 nm and at 585 nm in the
acetate buffer solution increase after the addition of dtpa, and start
shifting to 387 nm and 558 nm, respectively. The increase of the
absorption of the two bands is time dependent. The stoichiometry of
the Cr(III):dtpa complex is described to be 1:1. The 1:1.1 of Cr(III) –
dtpa mixture was heated to 70 oC for about 5 minutes. The absorption
spectrum is in good agreement with that reported [79]. The violet
product has the formula; [CrIIIdtpa(H2O)]2-, the Cr(III) in the 1:1
complex with dtpa is described to be coordinated with five dents of the
dtpa. The remaining three coordination sites of dtpa are protonated in
acidic solution and the six`s coordination site of Cr(III) is occupied by
a H2O [78,79].
ϯϲ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
The solutions of the complex were used within a week after their
preparation. A precipitate of chromium(III)-dtpa was formed when the
solution is left for more than a week [80]. It was found that at the end
of the oxidation reaction by IO4? chromium(VI) was formed by the
sym-diphenylcarbazide test [76].
3.3 Kinetic procedures.
The rate of each reaction was followed spectrophotometrically. A
Shimadzu UV- visible 1800 spectrophotometer, equipped with a
thermostated cell holder stable to ± 0.1oC, was used to follow the
reactions.
In the case of [CrIIIdtpa(H2O)]2- and [CrIIIcdta(H2O)]? the formation of
Cr(VI) was followed at the wavelength range of 360 - 370 nm
depending on the pH of the reaction.
The formation of Cr(V) which is produced from the oxidation of
[CrIII(phen)2(H2O)2]3+ was followed at 415 nm. At this wavelength
there is an appreciable change of absorbance.
ϯϳ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
The pH of the reaction solutions was measured on a Hanna Model 211
pH meter (± 0.01). The pH of the reaction mixture was found to be
always constant during the reaction run.
All the reactants except the IO4? were thermostated at the required
temperature for about 15 – 20 minutes to reach thermal equilibrium.
The required amount of separately thermostated IO4? stock solution
was then added, and after they were thoroughly mixed and quickly
transferred to an absorption
cell, recording the
absorbance
commenced. Pseudo-first order conditions were maintained in all runs
by using a large excess (= 15 fold)
of [IO4?] in the case of
[CrIIIcdta(H2O)]? and [CrIIIdtpa(H2O)]2- and (= 10 fold) of [IO4?] in the
case of [CrIII(phen)2(H2O)2]3+ over that of complex. Ionic strength
was kept constant by using a solution of NaNO3 of known
concentration. In a few runs LiClO4 was used to adjust ionic strength
instead of NaNO3.
3.4 Determination of the order and rate constant of the reaction
According to Beer’s law, the absorbance of a reactant or a product is
proportional to its concentration. Therefore, provided a region of the
spectrum is chosen where the absorption is due to a single compound
ϯϴ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
in
the
reaction
mixture,
the
reaction
can
be
followed
spectrophotometrically by measurement of the absorbance at that
wavelength as a function of time. The absorbance of the required
species (reactant or product) At is measured as a function of time, and
the infinity time reading A∞ is the absorbance at the end of the
reaction. These measurements were followed at wavelength, where the
absorbance is maximal in the pH range used. When a plot of ln(A∞ At) vs time is straight line, the reaction is considered to be first order.
If there is a deviation from linearity, then, we try a plot of 1/(A∞ - At)
vs time, if it gives a good straight line, the reaction is considered to has
a second order dependence.
3.5 Determination of thermodynamic parameters
The enthalpies, ? H*, and entropies, ? S*, of activation for the
oxidation of complexes by IO4? were calculated using either Eyring
equation, eq. (3.1), or Arrhenius equation, eq. (3.2), where T =
absolute temperature in degrees Kelvin, kB Boltzmann's constant
[1.381 x 10
-23
J K-1], h = Plank constant [6.63 x 10
-34
Js], A =
frequency factor [s-1], Ea = activation energy [kJ/mole], R = gas
constant [8.314 J].
ϯϵ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
ln(k/T) = [-(? H*/R)(1/T)] + [ln(kB/h) + (? S*/R)]
(3.1)
ln k = -Ea/RT + ln A
(3.2)
A plot of ln(k/T) against l/T is linear, with a slope, - ? H*/R and an
intercept [(ln (kB/h) + (? S*/R)] = (23.8 + ? S*/R). Both Arrhenius and
Eyring plots are used and give very similar results. The quantities ? H*
and ? S* are almost universally preferred for discussion of solution
kinetics and will be used hereafter [2].
ϰϬ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Chapter(IV)
4. Results
4. A [CrIII(phen)2(H2O)2]3+ complex
4. A.1 Characterization of the complex
The complex [CrIII(phen)3]3+ is not formed by the direct reaction of
[CrIII(H2O)6]3+ with 1,10 phenanthroline. It is prepared either by
reacting [CrII(H2O)6]2+ with 1,10 phenanthroline followed by oxidation
of the Cr(II) complex to Cr(III) complex or by substituting an excellent
leaving ligand such as trifluoromethanesulfonate (triflate) [81]. The
[CrIII(phen)2(H2O)2]3+ complex displayed absorption peak at 497nm, in
aqueous solutions as shown in Fig. 4.1. This peak position is in fairly
good agreement with the literature values (which are between 495 nm
to 500 nm) and the molar absorption was determined as 41.3 M-1 cm1
[82].
Table
4.A.1.
Assignment
of
the
IR
[CrIII(phen)2(H2O)2]3+ complex;
[CrIII(phen)2(H2O)2]3+
Assignment
3514
?OH¯ water
1581
Phen
ϰϭ
–
Spectrum
of
the
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
1279
?C-N
800-900
Cr–O
4.A.2 Stoichiometry of the reaction
The stoichiometry of the reaction showed that the reaction is consistent
with eq. (4.1). In this reaction, IO4? acts as a two-electron oxidant and
chromium(III) complex as a two-electron reductant. In a separate
experiment, it was shown that there is no reaction between cis[CrIII(phen)2(H2O)2]3+
and
IO3? under
the
employed
reaction
conditions.
cis-[CrIII(phen)2(H2O)2]3+ + IO4?? cis-[CrV(phen)2(O)2]+ + IO3? + H2O
+ 2H+ (4.1)
Fig. 4.1. Absorption spectrum of cis-[CrIII(phen)2(H2O)2]3+ in aqueous
solution.
ϰϮ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
4.A.3 Oxidation product
The UV-visible absorption spectra of the oxidation product of cis[CrIII(phen)2(H2O)2]3+ by IO4? in presence of sulphate buffer, were
recorded on Schimadzu UV-1800 spectrophotometer as a function of
time over the 300-700 nm range, Fig. 4.2. It is obvious from this figure
that the chromium(III) complex changed slowly to the final
chromium(V) product, and the latter has a shoulder at 415 nm (e =
85.5) and 555 nm (e =16.0). The yellow-brown colour did not change
when sym-diphenylcarbazide was added to the solution at the end of
the reaction. This confirms the absence of chromium(VI).
Fig. 4.2. Absorption spectra of the reaction mixture at different time
intervals, at cis-[CrIII(phen)2(H2O)23+] = 2.0 x 10-4 M, [IO4?] = 5.0 x 103
M, pH = 3.32, I = 0.30 M and T = 25.0 oC.
4.A.4 Results of the kinetic study
ϰϯ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Kinetic measurements were carried out under pseudo-first order
conditions with [IO4?] = 10[Cr(III)]. Plots of ln(A8 -At) vs time, where
At and A8 are the absorbance values at time t and infinity respectively,
are linear up to 85% of reaction.
4.A.4.1 Effect of variation of complex concentration on the rate of
the reaction
The rate of oxidation of cis-[CrIII(phen)2(H2O)2]3+ by IO4? was studied
at constant IO4? concentration of 0.01 M, ionic strength = 0.30 M, T =
25.0 oC and pH = 3.33. The complex concentration was varied over the
range (1.00 – 6.00) x 10-4 M. Plots of ln(A8 -At) versus time, where A8
and At are absorbance values at infinity and time t respectively, are
linear up to 85% of reaction. The results are collected in Tables 4.A.2
- 4.A.6. Fig. 4.3 represents the fitting of first order dependence on the
concentration of the complex. kobs values, at constant reaction
conditions are independent of the initial [CrIII(phen)2(H2O)23+] as
shown in Table 4.A.7. This is indicative of first order dependence on
complex concentration. The rate law of the reaction is described by eq.
(4.2):
Rate = kobs [CrIII(phen)2(H2O)23+]
(4.2)
ϰϰ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.2. Kinetic data for the reaction at [CrIII(phen)2(H2O)2 3+ ] =
1.00 x 10-4 M, [IO4?] = 0.01M, pH = 3.33, I = 0.30 M and T = 25.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
180
200
220
240
At
0.0353
0.0442
0.0482
0.0517
0.0544
0.0571
0.0598
0.0617
0.0638
0.0656
0.0674
0.0689
0.0702
A8
0.0851
0.0851
0.0851
0.0851
0.0851
0.0851
0.0851
0.0851
0.0851
0.0851
0.0851
0.0851
0.0851
A8 - At
0.0498
0.0409
0.0369
0.0334
0.0307
0.0280
0.0253
0.0234
0.0213
0.0195
0.0177
0.0162
0.0149
-ln(A8 - At)
3.00
3.20
3.30
3.40
3.48
3.58
3.68
3.76
3.85
3.94
4.03
4.12
4.21
Table 4.A.3. Kinetic data for the reaction at [CrIII(phen)2(H2O)2 3+ ] =
1.50 x 10-4 M, [IO4?] = 0.01 M, pH = 3.33, I = 0.30 M and T = 25.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
180
200
At
0.0634
0.0764
0.0818
0.0864
0.0907
0.0945
0.0986
0.1018
0.1042
0.1067
0.1090
A8
0.1335
0.1335
0.1335
0.1335
0.1335
0.1335
0.1335
0.1335
0.1335
0.1335
0.1335
A8 - At
0.0701
0.0571
0.0517
0.0471
0.0428
0.039
0.0349
0.0317
0.0293
0.0268
0.0245
ϰϱ
-ln(A8 - At)
2.66
2.86
2.96
3.06
3.15
3.24
3.36
3.45
3.53
3.62
3.71
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
220
240
260
0.1112
0.1131
0.1147
0.1335
0.1335
0.1335
0.0223
0.0204
0.0188
3.80
3.89
3.97
4.00
-ln(A∞ - At)
3.00
2.00
1.00
0.00
0
50
100
150
200
250
300
Tim e/s
Fig. 4.3. First order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate at [CrIII(phen)2(H2O)23+] = 1.50 x 10-4 M, [IO4?] = 0.01 M,
pH = 3.33, I = 0.30 M and T = 20.0 oC.
Table 4.A.4. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 0.01M, pH = 3.33, I = 0.30 M and T = 25.0 oC;
Time/s
0
20
40
60
At
0.0618
0.0777
0.0858
0.0951
A8
0.1788
0.1788
0.1788
0.1788
ϰϲ
A8 - At
0.1170
0.1011
0.093
0.0837
-ln(A8 - At)
2.15
2.29
2.38
2.48
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
80
100
120
140
160
180
200
220
240
260
Table 4.A.5.
0.1014
0.1091
0.1159
0.1213
0.1264
0.1308
0.1352
0.1391
0.1425
0.1456
Kinetic data
0.1788
0.0774
2.56
0.1788
0.0697
2.66
0.1788
0.0629
2.77
0.1788
0.0575
2.86
0.1788
0.0524
2.95
0.1788
0.0480
3.04
0.1788
0.0436
3.13
0.1788
0.0397
3.23
0.1788
0.0363
3.32
0.1788
0.0332
3.41
III
for the reaction at [Cr (phen)2(H2O)23+ ] =
4.00 x 10-4 M, [IO4?] = 0.01M, pH = 3.33, I = 0.30 M and T = 25.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
At
0.1009
0.1165
0.1327
0.1480
0.1618
0.1744
0.1858
0.1964
0.2067
0.2155
0.2239
0.2319
0.2392
0.2456
0.2508
A8
0.3115
0.3115
0.3115
0.3115
0.3115
0.3115
0.3115
0.3115
0.3115
0.3115
0.3115
0.3115
0.3115
0.3115
0.3115
A8 - At
0.2106
0.1950
0.1788
0.16348
0.1497
0.1371
0.1257
0.1151
0.1048
0.0960
0.0876
0.0796
0.0723
0.0659
0.0607
-ln(A8 - At)
1.56
1.63
1.72
1.81
1.90
1.99
2.07
2.16
2.26
2.34
2.43
2.53
2.63
2.72
2.80
Table 4.A.6. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
6.00 x 10-4 M, [IO4?] = 0.01 M, pH = 3.33, I = 0.30 M and T = 25.0 oC;
ϰϳ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Time/s
At
0
0.1501
20
0.1773
40
0.2042
60
0.2261
80
0.2487
100
0.2679
120
0.2867
140
0.3047
160
0.3193
180
0.3336
200
0.3467
220
0.3588
240
0.3691
260
0.3793
280
0.3884
Table 4.A.7. Summary
A8
A8 - At
-ln(A8 - At)
0.4852
0.3351
1.09
0.4852
0.3079
1.18
0.4852
0.2810
1.27
0.4852
0.2591
1.35
0.4852
0.2365
1.44
0.4852
0.2173
1.53
0.4852
0.1985
1.62
0.4852
0.1805
1.71
0.4852
0.1659
1.80
0.4852
0.1516
1.89
0.4852
0.1385
1.98
0.4852
0.1264
2.07
0.4852
0.1161
2.15
0.4852
0.1059
2.25
0.4852
0.0968
2.34
table for the variation of kobs with
[CrIII(phen)2(H2O)23+] at [IO4?] = 0.01 M, pH = 3.33, I = 0.30 M and T
= 25.0 oC;
104[Cr(III)], M
103 kobs, s-1
1.00
4.57 ± 0.03
1.50
4.64 ± 0.04
2.00
4.68 ± 0.03
4.00
4.52 ± 0.02
6.00
4.45 ± 0.03
4.A.4.2 Effect of periodate concentration on the rate of reaction
The oxidation reaction was carried out at constant concentration of cis[CrIII(phen)2(H2O)2]3+ (2.00 x 10-4 M), using different concentrations
ϰϴ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
of periodate (0.20 - 5.00) x 10-2 M, ionic strength = 0.30 M, different
pH values in the range (2.51 – 4.39) and the temperature range (20.0 40.0 ? C). It is obvious from the results that kobs does not vary linearly
with [IO4?] at all pH values and temperature ranges covered in this
study. Plots of 1/kobs versus 1/[IO4?] are linear at all pH and
temperature values with an intercepts I1 and slopes S1. These results
indicate a complex dependence on [IO4?]. The dependence of kobs on
[IO4?] is thus described by eq. (4.3);
kobs = a[IO4?]/(b + c[IO4?])
(4.3)
4. A.4.2.1 Variation of [IO4?] at 20.0 oC
Under fixed reaction conditions, the effect of IO4? on the rate of
oxidation of [CrIII (phen)2(H2O)2]3+ was investigated. The pH was
varied from 2.51 – 4.39. Values of intercepts I1 and slopes S1 obtained
at various pH values are summarized in Table 4.A.43. Values of
intercepts (I2 and I3) and slopes (S2 and S3) obtained from plots of I1
against [H+], Fig. 4.14, and S1 against [H+], Fig. 4.15, are shown in
Table 4.A.44.
4.A.4.2.1.1 Variation of [IO4?] at pH = 2.51
ϰϵ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
The kinetic data for the effect of IO4? on the rate of oxidation of [CrIII
(phen)2(H2O)2]3+ at T = 20 oC and pH = 2.51 are collected in Tables
4.A.8 – 4.A.13 and the first order fitting represented as in Fig. 4.4. The
dependence of kobs on [IO4?] is summarized in Table 4.A.14. Plotting
of 1/kobs vs 1/[IO4?], was found to be linear with an intercept I1 and a
slope S1 as shown in Fig. 4.13.
Table 4.A.8. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-3 M, pH = 2.51, I = 0.30 M and T =
20.0 oC;
Time/s
0
120
240
360
480
600
720
840
960
1080
1200
1320
1440
1560
At
0.0718
0.0876
0.0953
0.1012
0.1064
0.1122
0.1172
0.1211
0.1249
0.1291
0.1332
0.1367
0.1403
0.1428
A8
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
ϱϬ
A8 - At
0.1270
0.1112
0.1035
0.0976
0.0924
0.0866
0.0816
0.0777
0.0739
0.0697
0.0656
0.0621
0.0585
0.0560
-ln(A8 - At)
2.06
2.20
2.27
2.33
2.38
2.45
2.51
2.55
2.61
2.66
2.72
2.78
2.84
2.88
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.9. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 2.51, I = 0.30 M and T =
20.0 oC;
Time/s
0
120
240
360
480
600
720
840
960
1080
1200
1320
1440
At
0.0703
0.0909
0.1002
0.1077
0.1131
0.1178
0.1237
0.1291
0.1329
0.1377
0.1412
0.1451
0.1485
A8
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
A8 - At
0.1281
0.1075
0.0982
0.0907
0.0853
0.0806
0.0747
0.0693
0.0655
0.0607
0.0572
0.0533
0.0499
-ln(A8 - At)
2.05
2.23
2.32
2.40
2.46
2.52
2.59
2.67
2.73
2.80
2.86
2.93
3.00
3.00
2.50
-ln(A∞ - At)
2.00
1.50
1.00
0.50
0.00
0
400
800
time/s
ϱϭ
1200
1600
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.4. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 4.00 x 10-3
M, pH = 2.51, I = 0.30 M and T = 20.0 oC.
Table 4.A.10. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 8.00 x 10-3 M, pH = 2.51, I = 0.30 M and T =
20.0 oC;
Time/s
0
120
240
360
480
600
720
840
960
1080
1200
1320
1440
At
0.0689
0.0845
0.0935
0.1016
0.1081
0.1141
0.1192
0.1261
0.1313
0.1365
0.1408
0.1456
0.1491
A8
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
A8 - At
0.1297
0.1141
0.1051
0.097
0.0905
0.0845
0.0794
0.0725
0.0673
0.0621
0.0578
0.0530
0.0495
-ln(A8 - At)
2.04
2.17
2.25
2.33
2.40
2.47
2.53
2.62
2.70
2.78
2.85
2.94
3.01
Table 4.A.11. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 1.00 x 10-2 M, pH = 2.51, I = 0.30 M and T =
20.0 oC;
Time/s
0
120
240
360
At
0.0822
0.0983
0.1071
0.114
A8
0.1984
0.1984
0.1984
0.1984
A8 - At
0.1162
0.1001
0.0913
0.0844
ϱϮ
-ln(A8 - At)
2.15
2.30
2.39
2.47
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
480
600
720
840
960
1080
1200
1320
1440
0.1203
0.1266
0.1311
0.1366
0.1406
0.1452
0.1489
0.1526
0.1557
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.0781
0.0718
0.0673
0.0618
0.0578
0.0532
0.0495
0.0458
0.0427
2.55
2.63
2.70
2.78
2.85
2.93
3.01
3.08
3.15
Table 4.A.12. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-2 M, pH = 2.51, I = 0.30 M and T =
20.0 oC;
Time/s
0
120
240
360
480
600
720
840
960
1080
1200
1320
1440
At
0.0755
0.0918
0.1012
0.1092
0.1151
0.1212
0.1277
0.1331
0.1372
0.1432
0.1475
0.1513
0.1546
A8
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
A8 - At
0.1231
0.1068
0.0974
0.0894
0.0835
0.0774
0.0709
0.0655
0.0614
0.0554
0.0511
0.0473
0.0440
ϱϯ
-ln(A8 - At)
2.09
2.24
2.33
2.41
2.48
2.56
2.65
2.73
2.79
2.89
2.97
3.05
3.12
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.13. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-2 M, pH = 2.51, I = 0.30 M and T =
20.0 oC;
Time/s
0
120
240
360
480
600
720
840
960
1080
1200
1320
1440
At
0.0834
0.0976
0.1062
0.1134
0.1194
0.1262
0.1315
0.1361
0.1409
0.1462
0.1506
0.1541
0.1574
A8
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
A8 - At
0.1144
0.1002
0.0916
0.0844
0.0784
0.0716
0.0663
0.0617
0.0569
0.0516
0.0472
0.0437
0.0404
-ln(A8 - At)
2.17
2.30
2.39
2.47
2.55
2.64
2.71
2.79
2.87
2.96
3.05
3.13
3.21
Table4.A.14. Summary table for the variation of kobs with [IO4?], at
[CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, I = 0.30 M, pH = 2.51 and T =
20.0 oC;
102[IO4?],
M
0.20
0.40
0.80
1.00
2.00
4.00
1/[IO4?], M104kobs, s-1
4.73 ± 0.01
5.70 ± 0.01
6.30 ± 0.01
6.40 ± 0.01
6.70 ± 0.01
6.87 ± 0.01
1
500
250
125
100
50
25
4.A.4.2.1.2 Variation of [IO4?] at pH = 2.70
ϱϰ
1/kobs, s
2114
1754
1587
1562
1492
1455
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
The kinetic data for the effect of IO4? on the rate of oxidation of [CrIII
(phen)2(H2O)2]3+ at T = 20 oC and pH = 2.70 are collected in Tables
4.A.15 – 4.A.20 and the first order fitting represented as in Fig. 4.5.
The dependence of kobs on [IO4?] is summarized in Table 4.A.21.
Plotting of 1/kobs vs 1/[IO4?], was found to be linear with an intercept I1
and a slope S1 as shown in Fig. 4.13.
Table 4.A.15. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-3 M, pH = 2.70, I = 0.30 M and T =
20.0 oC;
Time/s
At
A8
A8 - At
-ln(A8 - At)
0
0.0718
0.1978
0.1260
2.07
60
0.0818
0.1978
0.1160
2.15
120
0.0876
0.1978
0.1102
2.21
180
0.0925
0.1978
0.1053
2.25
240
0.0964
0.1978
0.1014
2.29
300
0.1018
0.1978
0.0960
2.34
360
0.1053
0.1978
0.0925
2.38
420
0.1097
0.1978
0.0881
2.43
480
0.1127
0.1978
0.0851
2.46
540
0.1156
0.1978
0.0822
2.50
600
0.1195
0.1978
0.0783
2.55
660
0.1219
0.1978
0.0759
2.58
720
0.1251
0.1978
0.0727
2.62
780
0.1273
0.1978
0.0705
2.65
840
0.1304
0.1978
0.0674
2.70
900
0.1332
0.1978
0.0646
2.74
Table 4.A.16. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 2.70, I = 0.30 M and T =
20.0 oC;
Time/s
0
At
0.0721
A8
0.1979
ϱϱ
A8 - At
0.1258
-ln(A8 - At)
2.07
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
60
120
180
240
300
360
420
480
540
600
660
720
780
840
900
0.0874
0.0929
0.0968
0.1024
0.1077
0.1129
0.1164
0.1195
0.1237
0.1269
0.1301
0.1339
0.1361
0.1391
0.1423
0.1979
0.1979
0.1979
0.1979
0.1979
0.1979
0.1979
0.1979
0.1979
0.1979
0.1979
0.1979
0.1979
0.1979
0.1979
0.1105
0.1050
0.1011
0.0955
0.0902
0.0850
0.0815
0.0784
0.0742
0.0710
0.0678
0.0640
0.0618
0.0588
0.0556
2.20
2.25
2.29
2.35
2.41
2.47
2.51
2.55
2.60
2.65
2.69
2.75
2.78
2.83
2.89
3.00
2.50
-ln(A∞ - At)
2.00
1.50
1.00
0.50
0.00
0
200
400
600
800
1000
tim e/s
Fig. 4.5. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 4.00 x 10-3
M, pH = 2.70, I = 0.30 M and T = 20.0 oC.
ϱϲ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.17. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 8.00 x 10-3 M, pH = 2.70, I = 0.30 M and T =
20.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
660
720
780
840
900
At
0.0643
0.0748
0.0824
0.088
0.0938
0.1001
0.1055
0.1098
0.1138
0.1179
0.1219
0.1266
0.1299
0.1337
0.1369
0.1406
A8
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
A8 - At
0.1335
0.1230
0.1154
0.1098
0.1040
0.0977
0.0923
0.0880
0.0840
0.0799
0.0759
0.0712
0.0679
0.0641
0.0609
0.0572
-ln(A8 - At)
2.01
2.10
2.16
2.21
2.26
2.33
2.38
2.43
2.48
2.53
2.58
2.64
2.69
2.75
2.80
2.86
Table 4.A.18. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 1.00 x 10-4 M , pH = 2.70, I = 0.30 M and T =
20.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
At
0.0835
0.0934
0.0995
0.1053
0.1083
0.1135
0.1176
0.1216
0.1249
A8
0.196
0.196
0.196
0.196
0.196
0.196
0.196
0.196
0.196
A8 - At
0.1125
0.1026
0.0965
0.0907
0.0877
0.0825
0.0784
0.0744
0.0711
ϱϳ
-ln(A8 - At)
2.18
2.28
2.34
2.40
2.43
2.49
2.55
2.60
2.64
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
540
0.1289
0.196
0.0671
2.70
600
0.1328
0.196
0.0632
2.76
660
0.1366
0.196
0.0594
2.82
720
0.1401
0.196
0.0559
2.88
780
0.1429
0.196
0.0531
2.94
840
0.1457
0.196
0.0503
2.99
900
0.1481
0.196
0.0479
3.04
III
Table 4.A.19. Kinetic data for the reaction at [Cr (phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-2 M, pH = 2.70, I = 0.30 M and T =
20.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
660
720
780
840
900
At
0.0715
0.0837
0.0903
0.0979
0.1032
0.1083
0.1129
0.1182
0.1225
0.1261
0.1308
0.1349
0.1373
0.1401
0.1436
0.1472
A8
0.1976
0.1976
0.1976
0.1976
0.1976
0.1976
0.1976
0.1976
0.1976
0.1976
0.1976
0.1976
0.1976
0.1976
0.1976
0.1976
A8 - At
0.1261
0.1139
0.1073
0.0997
0.0944
0.0893
0.0847
0.0794
0.0751
0.0715
0.0668
0.0627
0.0603
0.0575
0.0540
0.0504
-ln(A8 - At)
2.07
2.17
2.23
2.31
2.36
2.42
2.47
2.53
2.59
2.64
2.71
2.77
2.81
2.86
2.92
2.99
Table 4.A.20. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-2 M, pH = 2.70, I = 0.30 M and T =
20.0 oC;
Time/s
0
60
At
0.0834
0.0922
A8
0.1962
0.1962
ϱϴ
A8 - At
0.1128
0.1040
-ln(A8 - At)
2.18
2.26
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
120
0.0984
180
0.1033
240
0.1109
300
0.1155
360
0.1199
420
0.1242
480
0.1287
540
0.1315
600
0.1346
660
0.1383
720
0.1418
780
0.1451
840
0.1482
900
0.1509
Table 4.A.21. Summary
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
table for the
0.0978
0.0929
0.0853
0.0807
0.0763
0.0720
0.0675
0.0647
0.0616
0.0579
0.0544
0.0511
0.0480
0.0453
variation of kobs
2.32
2.38
2.46
2.52
2.57
2.63
2.70
2.74
2.79
2.85
2.91
2.97
3.04
3.09
with [IO4?],
[CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, I = 0.30 M, pH = 2.70 and T =
20.0 oC;
102[IO4?],
M
0.20
0.40
0.80
1.00
2.00
4.00
103kobs, s-1
0.68 ±
0.01
0.81 ±
0.01
0.89 ±
0.01
0.91 ±
0.01
0.95 ±
0.01
0.98 ±
0.01
1/[IO4?],
M-1
1/kobs, s
500
1470.59
250
1234.57
125
1123.60
100
1098.90
50
1052.63
25
1020.41
4.A.4.2.1.3 Variation of [IO4?] at pH = 3.03
ϱϵ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
The kinetic data for the effect of IO4? on the rate of oxidation of [CrIII
(phen)2(H2O)2]3+ at T = 20 oC and pH = 3.03 are presented in Tables
4.A.22 – 4.A.27. The first order fitting for some runs are represented in
Figs. 4.6 – 4.10. The dependence of kobs on [IO4?] is summarized in
Table 4.A.28. Plotting of 1/kobs vs 1/[IO4?], was found to be linear with
an intercept I1 and a slope S1 as shown in Fig. 4.13.
Table 4.A.22. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-3 M, pH = 3.03, I = 0.30 M and T =
20.0 oC;
Time/s
At
A8
A8 - At
-ln(A8 - At)
0
0.0758
0.1946
0.1188
2.13
60
0.0886
0.1946
0.1060
2.24
120
0.0982
0.1946
0.0964
2.34
180
0.1054
0.1946
0.0892
2.42
240
0.1122
0.1946
0.0824
2.50
300
0.1185
0.1946
0.0761
2.58
360
0.1246
0.1946
0.0700
2.66
420
0.1297
0.1946
0.0649
2.73
480
0.1349
0.1946
0.0597
2.82
540
0.1398
0.1946
0.0548
2.90
600
0.1437
0.1946
0.0509
2.98
660
0.1477
0.1946
0.0469
3.06
720
0.1518
0.1946
0.0428
3.15
780
0.1548
0.1946
0.0398
3.22
III
Table 4.A.23. Kinetic data for the reaction at [Cr (phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 3.03, I = 0.30 M and T =
20.0 oC;
Time
0
60
90
120
150
At
0.0721
0.0911
0.0961
0.1021
0.1059
A8
0.1941
0.1941
0.1941
0.1941
0.1941
A8 - At
0.1220
0.1030
0.0980
0.0920
0.0882
ϲϬ
-ln(A8 - At)
2.10
2.27
2.32
2.39
2.43
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
180
210
240
270
300
330
360
390
420
450
480
510
540
570
600
630
0.1105
0.1129
0.1166
0.1206
0.1240
0.1267
0.1301
0.1326
0.1361
0.1382
0.1404
0.1428
0.145
0.1476
0.1497
0.1517
0.1941
0.1941
0.1941
0.1941
0.1941
0.1941
0.1941
0.1941
0.1941
0.1941
0.1941
0.1941
0.1941
0.1941
0.1941
0.1941
0.0836
0.0812
0.0775
0.0735
0.0701
0.0674
0.0640
0.0615
0.0580
0.0559
0.0537
0.0513
0.0491
0.0465
0.0444
0.0424
2.48
2.51
2.56
2.61
2.66
2.70
2.75
2.79
2.85
2.88
2.92
2.97
3.01
3.07
3.11
3.16
3.00
2.50
-ln(A∞ - At)
2.00
1.50
1.00
0.50
0.00
0
100
200
300
400
500
600
700
time/s
Fig. 4.6. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 4.00 x 10-3
M, pH = 3.03, I = 0.30 M and T = 20.0 oC.
Table 4.A.24. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 8.00 x 10-3 M, pH = 3.03, I = 0.30 M and T =
20.0 oC;
Time/s
At
A8
A8 - At
ϲϭ
-ln(A8 - At)
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
0
60
120
180
240
300
360
420
480
540
600
660
720
780
0.0581
0.0796
0.0911
0.1010
0.1099
0.1171
0.1248
0.1326
0.1379
0.1434
0.1487
0.1526
0.1563
0.1603
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1365
0.1150
0.1035
0.0936
0.0847
0.0775
0.0698
0.0620
0.0567
0.0512
0.0459
0.0420
0.0383
0.0343
1.99
2.16
2.27
2.37
2.47
2.56
2.66
2.78
2.87
2.97
3.08
3.17
3.26
3.37
3.00
2.50
-ln(A∞ − Α τ
2.00
1.50
1.00
0.50
0.00
0
100
200
300
400
500
600
700
time/s
Fig. 4.7. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 8.00 x 10-3
M, pH = 3.03, I = 0.30 M and T = 20.0 oC.
ϲϮ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.25. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 1.00 x 10-2 M, pH = 3.03, I = 0.30 M and T =
20.0 oC;
At
0.0721
0.1022
0.1113
0.1183
0.1260
0.1323
0.1397
0.1449
0.1496
0.1538
0.1577
0.1614
0.1643
A8
0.1943
0.1943
0.1943
0.1943
0.1943
0.1943
0.1943
0.1943
0.1943
0.1943
0.1943
0.1943
0.1943
A8 - At
0.1222
0.0921
0.0830
0.0760
0.0683
0.0620
0.0546
0.0494
0.0447
0.0405
0.0366
0.0329
0.0300
-ln(A8 - At)
2.10
2.38
2.49
2.58
2.68
2.78
2.91
3.01
3.11
3.21
3.31
3.41
3.51
3.00
2.50
-ln(A∞ - At)
Time/s
0
60
120
180
240
300
360
420
480
540
600
660
720
2.00
1.50
1.00
0.50
0.00
0
100
200
300
time/s
ϲϯ
400
500
600
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.8. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 1.00 x 10-2
M, pH = 3.03, I = 0.30 M and T = 20.0 oC.
Table 4.A.26. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-2 M, pH = 3.03, I = 0.30 M and T =
20.0 oC;
Time/s
0
30
60
90
120
150
180
210
240
270
300
330
360
390
420
450
480
510
540
At
0.0591
0.0724
0.0792
0.0862
0.0899
0.0952
0.1008
0.1048
0.1102
0.1149
0.1192
0.1233
0.1268
0.1306
0.1329
0.1369
0.1399
0.1428
0.1454
A8
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
0.1946
A8 - At
0.1355
0.1222
0.1154
0.1084
0.1047
0.0994
0.0938
0.0898
0.0844
0.0797
0.0754
0.0713
0.0678
0.0640
0.0617
0.0577
0.0547
0.0518
0.0492
-ln(A8 - At)
2.00
2.10
2.16
2.22
2.26
2.31
2.37
2.41
2.47
2.53
2.58
2.64
2.69
2.75
2.79
2.85
2.91
2.96
3.01
3.00
2.50
-ln(A∞ - At)
2.00
1.50
ϲϰ
1.00
0.50
0.00
0
100
200
300
time/s
400
500
600
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.9. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 2.00 x 10-2
M, pH = 3.03, I = 0.30 M and T = 20.0 oC.
Table 4.A.27. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-2 M, pH = 3.03, I = 0.30 M and T =
20.0 oC;
Time/s
0
60
90
120
150
180
210
240
270
300
330
360
390
420
450
480
510
540
570
At
0.0875
0.0941
0.1001
0.1056
0.1106
0.1141
0.1177
0.1222
0.1253
0.1297
0.1328
0.1376
0.1396
0.1431
0.1459
0.1480
0.1506
0.1530
0.1552
A8
0.1948
0.1948
0.1948
0.1948
0.1948
0.1948
0.1948
0.1948
0.1948
0.1948
0.1948
0.1948
0.1948
0.1948
0.1948
0.1948
0.1948
0.1948
0.1948
A8 - At
0.1073
0.1007
0.0947
0.0892
0.0842
0.0807
0.0771
0.0726
0.0695
0.0651
0.0620
0.0572
0.0552
0.0517
0.0489
0.0468
0.0442
0.0418
0.0396
ϲϱ
-ln(A8 - At)
2.23
2.30
2.36
2.42
2.47
2.52
2.56
2.62
2.67
2.73
2.78
2.86
2.90
2.96
3.02
3.06
3.12
3.17
3.23
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
3.00
-ln(A∞ - At)
2.50
2.00
1.50
1.00
0.50
0.00
0
100
200
300
400
500
600
time/s
Fig. 4.10. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 4.00 x 10-2
M, pH = 3.03, I = 0.30 M and T = 20.0 oC.
Table 4.A.28. Summary table for the variation of kobs with [IO4?], at
[CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, I = 0.30 M, pH = 3.03 and T =
20.0 oC;
102[IO4?],
M
0.20
0.40
0.80
1.00
2.00
4.00
103kobs, s-1
1.31 ±
0.01
1.53 ±
0.01
1.68 ±
0.01
1.72 ±
0.01
1.78 ±
0.01
1.82 ±
1/[IO4?]
M-1
1/kobs, s
500
763.36
250
653.59
125
595.24
100
581.40
50
25
561.80
549.45
ϲϲ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
0.01
4.A.4.2.1.4 Variation of [IO4?] at pH = 3.26
The kinetic data for the effect of IO4? on the rate of oxidation of [CrIII
(phen)2(H2O)2]3+ at T = 20 oC and pH = 3.26 are shown in Tables
4.A.29 – 4.A.34. An example for first order fitting is represented in
Fig. 4.11. The dependence of kobs on [IO4?] is summarized in Table
4.A.35. Plotting of 1/kobs vs 1/[IO4?], was found to be linear with an
intercept I1 and a slope S1 as shown in Fig. 4.13.
Table 4.A.29. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-3 M, pH = 3.26, I = 0.30 M and T =
20.0 oC;
Time/s
0
30
60
90
120
150
180
210
240
270
300
330
360
At
0.0885
0.1082
0.1148
0.1197
0.1240
0.1279
0.1315
0.1356
0.1396
0.1431
0.1459
0.1483
0.1511
A8
0.1958
0.1958
0.1958
0.1958
0.1958
0.1958
0.1958
0.1958
0.1958
0.1958
0.1958
0.1958
0.1958
A8 - At
0.1073
0.0876
0.0810
0.0761
0.0718
0.0679
0.0643
0.0602
0.0562
0.0527
0.0499
0.0475
0.0447
ϲϳ
-ln(A8 - At)
2.23
2.43
2.51
2.58
2.63
2.69
2.74
2.81
2.88
2.94
3.00
3.05
3.11
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
3.20
-ln(A∞ - At)
2.40
1.60
0.80
0.00
0
100
200
300
400
time, s
Fig. 4.11. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4¯?] = 4.00 x 103
M, pH = 3.26, I = 0.30 M and T = 20.0 oC.
Table 4.A.30. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 3.26, I = 0.30 M and T =
20.0 oC;
Time/s
0
30
60
90
120
150
180
210
240
270
300
330
At
0.0771
0.0935
0.1062
0.1114
0.1169
0.1226
0.1275
0.1317
0.1365
0.1408
0.1446
0.1479
A8
0.1955
0.1955
0.1955
0.1955
0.1955
0.1955
0.1955
0.1955
0.1955
0.1955
0.1955
0.1955
ϲϴ
A8 - At
0.1184
0.1020
0.0893
0.0841
0.0786
0.0729
0.0680
0.0638
0.0590
0.0547
0.0509
0.0476
-ln(A8 - At)
2.13
2.28
2.42
2.48
2.54
2.62
2.69
2.75
2.83
2.91
2.98
3.04
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
360
390
0.1511
0.1541
0.1955
0.1955
0.0444
0.0414
3.11
3.18
Table 4.A.31. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 8.00 x 10-3 M, pH = 3.26, I = 0.30 M and T =
20.0 oC;
Time/s
0
30
60
90
120
150
180
210
240
270
300
330
360
At
0.1110
0.1256
0.1313
0.1357
0.1402
0.1434
0.1487
0.1517
0.1547
0.1582
0.1611
0.1639
0.1664
A8
0.1957
0.1957
0.1957
0.1957
0.1957
0.1957
0.1957
0.1957
0.1957
0.1957
0.1957
0.1957
0.1957
A8 - At
0.0847
0.0701
0.0644
0.0600
0.0555
0.0523
0.0470
0.0440
0.0410
0.0375
0.0346
0.0318
0.0293
-ln(A8 - At)
2.47
2.66
2.74
2.81
2.89
2.95
3.06
3.12
3.19
3.28
3.36
3.45
3.53
Table 4.A.32. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 1.00 x 10-2 M, pH = 3.26, I = 0.30 M and T =
20.0 oC;
Time/s
0
30
60
90
At
0.0907
0.1098
0.1172
0.1239
A8
0.1978
0.1978
0.1978
0.1978
A8 - At
0.1071
0.0880
0.0806
0.0739
ϲϵ
-ln(A8 - At)
2.23
2.43
2.52
2.61
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
120
150
180
210
240
270
300
330
0.1298
0.1351
0.1395
0.1442
0.1484
0.1519
0.1554
0.1587
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
0.1978
0.0680
0.0627
0.0583
0.0536
0.0494
0.0459
0.0424
0.0391
2.69
2.77
2.84
2.93
3.01
3.08
3.16
3.24
Table 4.A.33. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-2 M, pH = 3.26, I = 0.30 M and T =
20.0 oC;
Time/s
0
30
60
90
120
150
180
210
240
270
300
At
0.1487
0.1554
0.1592
0.1622
0.1651
0.1674
0.1696
0.1718
0.1738
0.1754
0.1775
A8
0.1966
0.1966
0.1966
0.1966
0.1966
0.1966
0.1966
0.1966
0.1966
0.1966
0.1966
A8 - At
0.0489
0.0412
0.0374
0.0344
0.0315
0.0292
0.0270
0.0248
0.0228
0.0212
0.0191
-ln(A8 - At)
3.02
3.19
3.29
3.37
3.46
3.53
3.61
3.70
3.78
3.85
3.96
Table 4.A.34. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-2 M, pH = 3.26, I = 0.30 M and T =
20.0 oC;
Time/s
At
A8
A8 - At
ϳϬ
-ln(A8 - At)
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
0
30
60
90
120
150
180
210
240
270
300
0.0857
0.1015
0.1108
0.1184
0.1251
0.1313
0.1362
0.1412
0.1454
0.1497
0.1535
0.1975
0.1975
0.1975
0.1975
0.1975
0.1975
0.1975
0.1975
0.1975
0.1975
0.1975
0.1118
0.0960
0.0867
0.0791
0.0724
0.0662
0.0613
0.0563
0.0521
0.0478
0.0440
2.19
2.34
2.45
2.54
2.63
2.72
2.79
2.88
2.95
3.04
3.12
Table 4.A.35. Summary table for the variation of kobs with [IO4?], at
[CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, I = 0.30 M, pH = 3.26 and T =
20.0 oC;
102[IO4?],
M
0.20
0.40
0.80
1.00
2.00
4.00
103kobs, s-1
2.02 ± 0.02
2.36 ± 0.02
2.63 ± 0.03
2.68 ± 0.02
2.78 ± 0.03
2.85 ± 0.05
1/[IO4?],
M-1
500
250
125
100
50
25
1/kobs, s
495.05
423.73
380.23
373.13
359.71
350.88
4.A.4.2.1.5 Variation of [IO4?] at pH = 3.65
ϳϭ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
The kinetic data for the effect of IO4? on the rate of oxidation of [CrIII
(phen)2(H2O)2]3+ at T = 20 oC and pH = 3.65 are shown in Tables
4.A.36 – 4.A.41 and an example for first order fitting is represented in
Fig. 4.12. The dependence of kobs on [IO4?] is summarized in Table
4.A.42. Plotting of 1/kobs vs 1/[IO4?], was found to be linear with an
intercept I1 and a slope S1 as shown in Fig. 4.13.
Table 4.A.36. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-3 M, pH = 3.65, I = 0.30 M and T =
20.0 oC;
Time/s
0
30
60
90
120
150
180
210
240
270
300
330
At
0.0809
0.0931
0.1032
0.1128
0.1228
0.1307
0.1382
0.1434
0.1496
0.1539
0.1584
0.1619
A8
0.1965
0.1965
0.1965
0.1965
0.1965
0.1965
0.1965
0.1965
0.1965
0.1965
0.1965
0.1965
A8 - At
0.1156
0.1034
0.0933
0.0837
0.0737
0.0658
0.0583
0.0531
0.0469
0.0426
0.0381
0.0346
-ln(A8 - At)
2.16
2.27
2.37
2.48
2.61
2.72
2.84
2.94
3.06
3.16
3.27
3.36
3 .5 0
3 .0 0
-ln(A∞ - At)
2 .5 0
ϳϮ
2 .0 0
1 .5 0
1 .0 0
0 .5 0
0 .0 0
0
100
200
300
400
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.12. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 2.00 x 10-3
M, pH = 3.65, I = 0.30 M and T = 20.0 oC.
Table 4.A.37. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 3.65, I = 0.30 M and T =
20.0 oC;
Time/s
0
30
60
90
120
150
180
210
240
270
300
330
At
0.0772
0.0849
0.0977
0.1085
0.1193
0.1281
0.1352
0.1425
0.1488
0.1541
0.1587
0.1626
A8
0.1937
0.1937
0.1937
0.1937
0.1937
0.1937
0.1937
0.1937
0.1937
0.1937
0.1937
0.1937
A8 - At
0.1165
0.1088
0.0960
0.0852
0.0744
0.0656
0.0585
0.0512
0.0449
0.0396
0.0350
0.0311
ϳϯ
-ln(A8 - At)
2.15
2.22
2.34
2.46
2.60
2.72
2.84
2.97
3.10
3.23
3.35
3.47
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.38. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 8.00 x 10-3 M, pH = 3.65, I = 0.30 M and T =
20.0 oC;
Time/s
0
30
60
90
120
150
180
210
240
270
300
At
0.0973
0.1067
0.1173
0.1276
0.1351
0.1436
0.1495
0.1555
0.1608
0.1647
0.1689
A8
0.1945
0.1945
0.1945
0.1945
0.1945
0.1945
0.1945
0.1945
0.1945
0.1945
0.1945
A8 - At
0.0972
0.0878
0.0772
0.0669
0.0594
0.0509
0.0450
0.0390
0.0337
0.0298
0.0256
-ln(A8 - At)
2.33
2.43
2.56
2.70
2.82
2.98
3.10
3.24
3.39
3.51
3.67
Table 4.A.39. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 1.00 x 10-2 M, pH = 3.65, I = 0.30 M and T =
20.0 oC;
Time/s
0
30
60
90
120
150
180
210
240
270
300
330
At
0.0729
0.0821
0.0966
0.1088
0.1196
0.1293
0.1377
0.1457
0.1519
0.1579
0.1623
0.1663
A8
0.1947
0.1947
0.1947
0.1947
0.1947
0.1947
0.1947
0.1947
0.1947
0.1947
0.1947
0.1947
ϳϰ
A8 - At
0.1218
0.1126
0.0981
0.0859
0.0751
0.0654
0.0570
0.0490
0.0428
0.0368
0.0324
0.0284
-ln(A8 - At)
2.11
2.18
2.32
2.45
2.59
2.73
2.86
3.02
3.15
3.30
3.43
3.56
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.40. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-2 M, pH = 3.65, I = 0.30 M and T =
20.0 oC;
Time/s
0
30
60
90
120
150
180
210
240
270
300
330
At
0.0697
0.0849
0.0992
0.1113
0.1216
0.1313
0.1399
0.1475
0.1548
0.1593
0.1639
0.1681
A8
0.1943
0.1943
0.1943
0.1943
0.1943
0.1943
0.1943
0.1943
0.1943
0.1943
0.1943
0.1943
A8 - At
0.1246
0.1094
0.0951
0.0830
0.0727
0.0630
0.0544
0.0468
0.0395
0.0350
0.0304
0.0262
-ln(A8 - At)
2.08
2.21
2.35
2.49
2.62
2.76
2.91
3.06
3.23
3.35
3.49
3.64
Table 4.A.41. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-2 M, pH = 3.65, I = 0.30 M and T =
20.0 oC;
Time/s
0
30
60
90
120
At
0.0906
0.0977
0.1103
0.1216
0.1312
A8
0.1941
0.1941
0.1941
0.1941
0.1941
A8 - At
0.1035
0.0964
0.0838
0.0725
0.0629
ϳϱ
-ln(A8 - At)
2.27
2.34
2.48
2.62
2.77
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
150
180
210
240
270
300
330
0.1397
0.1474
0.1537
0.1592
0.1643
0.1681
0.1716
0.1941
0.1941
0.1941
0.1941
0.1941
0.1941
0.1941
0.0544
0.0467
0.0404
0.0349
0.0298
0.0260
0.0225
2.91
3.06
3.21
3.36
3.51
3.65
3.79
Table 4.A.42. Summary table for the variation of kobs with [IO4?], at
[CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, I = 0.30 M, pH = 3.65 and T =
20.0 oC;
102[IO4?],
M
0.20
0.40
0.80
1.00
2.00
4.00
1/[IO4?], M103kobs, s-1
3.70 ± 0.03
4.20 ± 0.02
4.56 ± 0.04
4.63 ± 0.02
4.79 ± 0.04
4.88 ± 0.02
1
500
250
125
100
50
25
1/kobs, s
270.27
238.10
219.30
215.98
208.77
204.92
Table 4.A.43. Values of intercepts and slopes at 20.0 oC and various
pH values obtained from plots of kobs-1 versus [IO4?]-1;
104[H+],
pH
M
10-2I1, s
10S1, M
13.80 ±
2.51
30.90
0.20
14.21 ± 0.04
2.70
20.41
9.35 ± 0.10
10.03 ± 0.03
3.03
9.33
4.52 ± 0.10
5.39 ± 0.01
ϳϲ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
3.26
5.50
3.05 ± 0.10
3.44 ± 0.01
3.65
2.30
1.38 ± 0.02
2.02 ± 0.01
2000
A
1/kobs, s
1600
1200
B
C
800
D
400
E
0
0
100
200
300
−
400
500
-1
1/[IO4 ], M
Fig. 4.13. Plots of kobs-1 versus [IO4?]-1 at pH values, (A) 2.51, (B) 2.70,
(C) 3.03 (D) 3.26 and (E) 3.65 at 20.0 oC.
16.0
14.0
12.0
8.0
-2
10 I1, s
10.0
6.0
4.0
2.0
0.0
0.0
5.0
10.0
15.0
20.0
4
25.0
+
10 [H ], M
ϳϳ
30.0
35.0
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.14. Dependence of I1 on [H+] at 20 oC.
14.0
12.0
10S1, M
10.0
8.0
6.0
4.0
2.0
0.0
0.0
5.0
10.0
15.0
4
20.0
25.0
30.0
35.0
+
10 [H ], M
Fig. 4.15. Dependence of S1 on [H+] at 20 oC.
Table 4.A.44. Values of I2, S2 and I3 S3 at 20 oC obtained from plots of
I1 vs [H+] and S1 vs [H+], respectively;
S2
(4.26 ± 0.08) x 10-5
S3
(4.32 ± 0.05) x 10-2
I2
(1.19 ± 0.14) x 10-2
I3
(5.40 ± 0.90) x 102
4.A.4.2.2 Variation of [IO4?] at 25.0 oC
ϳϴ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Under fixed reaction conditions, the effect of IO4? on the rate of
oxidation of [CrIII(phen)2(H2O)2]3+ was investigated. The pH was
varied from 2.81 – 4.39. Values of intercepts I1 and slopes S1 at various
pH values are summarized in Table 4.A.90. Values of intercepts (I2
and I3) and slopes (S2 and S3) at various pH values obtained from plots
of I1 against [H+], Fig. 4.28 and S1 against [H+], Fig. 4.29 are shown in
Table 4.A.91.
3.A.4.2.2.1 Variation of [IO4?] at pH = 2.81
The kinetic data for the effect of IO4? on the rate of oxidation of [CrIII
(phen)2(H2O)2]3+ by IO4? at T = 25 oC and pH = 2.81 are presented in
Tables 4.A.45 – 4.A.50 and an example for first order fitting
represented as in Fig. 4.16. The dependence of kobs on [IO4?] is
summarized in Table 4.A.51. Plotting of 1/kobs vs 1/[IO4?], was found
to be linear with an intercept I1 and a slope S1 as shown in Fig. 4.27.
Table 4.A.45. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-3 M, pH = 2.81, I = 0.30 M and T =
25.0 oC;
Time/s
At
A8
A8 - At
ϳϵ
-ln(A8 - At)
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
0
60
120
180
240
300
360
420
480
540
600
660
720
780
840
900
960
1020
1080
1140
0.0889
0.0992
0.1068
0.1128
0.1194
0.1258
0.1307
0.1356
0.1402
0.1444
0.1483
0.1518
0.1552
0.1574
0.1612
0.1638
0.166
0.1678
0.1702
0.1719
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1097
0.0994
0.0918
0.0858
0.0792
0.0728
0.0679
0.0630
0.0584
0.0542
0.0503
0.0468
0.0434
0.0412
0.0374
0.0348
0.0326
0.0308
0.0284
0.0267
2.21
2.31
2.39
2.46
2.54
2.62
2.69
2.76
2.84
2.92
2.99
3.06
3.14
3.19
3.29
3.36
3.42
3.48
3.56
3.62
Table 4.A.46. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 3.00 x 10-3 M, pH = 2.81, I = 0.30 M and T =
25.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
At
0.1103
0.1156
0.1261
0.1320
0.1373
0.1430
0.1479
0.1525
0.1571
0.1608
0.1646
A8
0.2071
0.2071
0.2071
0.2071
0.2071
0.2071
0.2071
0.2071
0.2071
0.2071
0.2071
A8 - At
0.0968
0.0915
0.0810
0.0751
0.0698
0.0641
0.0592
0.0546
0.0500
0.0463
0.0425
ϴϬ
-ln(A8 - At)
2.34
2.39
2.51
2.59
2.66
2.75
2.83
2.91
3.00
3.07
3.16
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
660
0.1677
0.2071
0.0394
3.23
III
Table 4.A.47. Kinetic data for the reaction at [Cr (phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 8.00 x 10-3 M, pH = 2.81, I = 0.30 M and T =
25.0 oC;
Time/s
0
120
240
360
480
600
720
840
960
1080
1200
1320
1440
1560
At
0.1020
0.1230
0.1351
0.1480
0.1563
0.1637
0.1699
0.1752
0.1794
0.1831
0.1860
0.1884
0.1903
0.1916
A8
0.1996
0.1996
0.1996
0.1996
0.1996
0.1996
0.1996
0.1996
0.1996
0.1996
0.1996
0.1996
0.1996
0.1996
A8 - At
0.0976
0.0766
0.0645
0.0516
0.0433
0.0359
0.0297
0.0244
0.0202
0.0165
0.0136
0.0112
0.0093
0.0080
-ln(A8 - At)
2.33
2.57
2.74
2.96
3.14
3.33
3.52
3.71
3.90
4.10
4.30
4.49
4.68
4.83
Table 4.A.48. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 1.00 x 10-2 M, pH = 2.81, I = 0.30 M and T =
25.0 oC;
Time/s
0
60
120
180
240
300
360
At
0.0932
0.1149
0.1236
0.1307
0.1361
0.1428
0.1481
A8
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
A8 - At
0.1066
0.0849
0.0762
0.0691
0.0637
0.0570
0.0517
ϴϭ
-ln(A8 - At)
2.24
2.47
2.57
2.67
2.75
2.86
2.96
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
420
480
540
600
660
0.1525
0.1571
0.1611
0.1649
0.1681
0.1998
0.1998
0.1998
0.1998
0.19998
0.0473
0.0427
0.0387
0.0369
0.0317
3.05
3.15
3.25
3.30
3.45
3.50
3.00
-ln(A∞ - At)
2.50
2.00
1.50
1.00
0.50
0.00
0
100
200
300
400
500
600
time/s
Fig. 4.16. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4¯] = 1.00 x 10-2
M, pH = 2.81, I = 0.30 M and T = 25.0 oC.
Table 4.A.49. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-2 M, pH = 2.81, I = 0.30 M and T =
25.0 oC;
Time/s
0
60
120
At
0.1110
0.1184
0.1263
A8
0.1999
0.1999
0.1999
A8 - At
0.0889
0.0815
0.0736
ϴϮ
-ln(A8 - At)
2.42
2.51
2.61
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
180
240
300
360
420
480
540
600
660
720
780
840
0.1333
0.1408
0.1458
0.1510
0.1552
0.1605
0.1637
0.1672
0.1704
0.1732
0.1758
0.1780
0.1999
0.1999
0.1999
0.1999
0.1999
0.1999
0.1999
0.1999
0.1999
0.1999
0.1999
0.1999
0.0666
0.0591
0.0541
0.0489
0.0447
0.0394
0.0362
0.0327
0.0295
0.0267
0.0241
0.0219
2.71
2.83
2.92
3.02
3.11
3.23
3.32
3.42
3.52
3.62
3.73
3.82
Table 4.A.50. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-2 M, pH = 2.81, I = 0.30 M and T =
25.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
660
720
780
840
At
0.1060
0.1175
0.1247
0.1326
0.1388
0.1451
0.1502
0.1552
0.1600
0.1635
0.1674
0.1706
0.1732
0.1759
0.1781
A8
0.1996
0.1996
0.1996
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
A8 - At
0.0936
0.0821
0.0749
0.0672
0.0610
0.0547
0.0496
0.0446
0.0398
0.0363
0.0324
0.0292
0.0266
0.0239
0.0217
ϴϯ
-ln(A8 - At)
2.37
2.50
2.59
2.70
2.80
2.91
3.00
3.11
3.22
3.32
3.43
3.53
3.63
3.73
3.83
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.51. Summary table for the variation of kobs with [IO4?], at
[CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, I = 0.30 M, pH = 2.81 and T =
25.0 oC;
102[IO4?],
M
0.20
0.30
0.80
1.00
2.00
4.00
1/[IO4?], M103kobs, s-1
1.22 ± 0.01
1.37 ± 0.02
1.59 ± 0.01
1.63 ± 0.01
1.68 ± 0.01
1.72 ± 0.01
1
500.0
333.3
125.0
100.0
50.0
25.0
1/kobs, s
819.7
729.9
628.9
613.5
595.2
581.4
4.A.4.2.2.2 Variation of [IO4?] at pH = 3.03
The kinetic data for the effect of IO4? on the rate of oxidation of [CrIII
(phen)2(H2O)2]3+ at T = 25 oC and pH = 3.03 are presented in Tables
4.A.52 – 4.A.57 and the first order fitting represented as in Fig. 4.17.
The dependence of kobs on [IO4?] is summarized in Table 4.A.58.
Plotting of 1/kobs vs 1/[IO4?], was found to be linear with an intercept I1
and a slope S1 as shown in Fig. 4.27.
Table 4.A.52. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-3 M, pH = 3.03, I = 0.30 M and T =
25.0 oC;
Time/s
0
60
120
180
240
300
At
0.0751
0.1079
0.1156
0.1241
0.1292
0.1363
A8
0.1876
0.1876
0.1876
0.1876
0.1876
0.1876
A8 - At
0.1175
0.0797
0.0720
0.0635
0.0584
0.0513
ϴϰ
-ln(A8 - At)
2.14
2.53
2.63
2.76
2.84
2.97
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
360
420
480
540
600
660
720
780
0.1412
0.1455
0.1500
0.1535
0.1566
0.1600
0.1629
0.1655
0.1876
0.1876
0.1876
0.1876
0.1876
0.1876
0.1876
0.1876
0.0464
0.0421
0.0376
0.0341
0.0310
0.0276
0.0247
0.0221
3.07
3.17
3.28
3.38
3.47
3.59
3.70
3.81
Table 4.A.53. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 3.03, I = 0.30 M and T =
25.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
660
720
780
840
900
At
0.0809
0.0867
0.0991
0.1093
0.1189
0.1272
0.1347
0.1416
0.1462
0.1504
0.1555
0.1589
0.1623
0.1652
0.1681
0.1702
A8
0.1884
0.1884
0.1884
0.1884
0.1884
0.1884
0.1884
0.1884
0.1884
0.1884
0.1884
0.1884
0.1884
0.1884
0.1884
0.1884
A8 - At
0.1075
0.1017
0.0893
0.0791
0.0695
0.0612
0.0537
0.0468
0.0422
0.0380
0.0329
0.0295
0.0261
0.0232
0.0203
0.0182
-ln(A8 - At)
2.23
2.29
2.42
2.54
2.67
2.79
2.92
3.06
3.17
3.27
3.41
3.52
3.65
3.76
3.90
4.01
Table 4.A.54. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4¯] = 8.00 x 10-3 M, pH = 3.03, I = 0.30 M and T =
25.0 oC;
ϴϱ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Time/s
0
30
60
90
120
150
180
210
240
270
300
330
360
390
420
450
At
0.1003
0.1102
0.1156
0.1202
0.1238
0.1279
0.132
0.1355
0.1394
0.1429
0.1457
0.1485
0.1511
0.1534
0.1557
0.1576
A8
0.1882
0.1882
0.1882
0.1882
0.1882
0.1882
0.1882
0.1882
0.1882
0.1882
0.1882
0.1882
0.1882
0.1882
0.1882
0.1882
A8 - At
0.0879
0.078
0.0726
0.0680
0.0644
0.0603
0.0562
0.0527
0.0488
0.0453
0.0425
0.0397
0.0371
0.0348
0.0325
0.0306
-ln(A8 - At)
2.43
2.55
2.62
2.69
2.74
2.81
2.88
2.94
3.02
3.09
3.16
3.23
3.29
3.36
3.43
3.49
Table 4.A.55. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 1.00 x 10-2 M, pH = 3.03, I = 0.30 M and T =
25.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
At
0.1060
0.1155
0.1247
0.1336
0.1408
0.1471
0.1517
0.1562
0.1605
0.164
0.1671
A8
0.1884
0.1884
0.1884
0.1884
0.1884
0.1884
0.1884
0.1884
0.1884
0.1884
0.1884
A8 - At
0.0824
0.0729
0.0637
0.0548
0.0476
0.0413
0.0367
0.0322
0.0279
0.0244
0.0213
ϴϲ
-ln(A8 - At)
2.50
2.62
2.75
2.90
3.04
3.19
3.30
3.44
3.58
3.71
3.85
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
4.00
-ln(A∞ - At)
3.00
2.00
1.00
0.00
0
100
200
300
400
500
600
time/s
Fig. 4.17. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 1.00 x 10-2
M, pH = 3.03, I = 0.30 M and T = 25.0 oC.
Table 4.A.56. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 3.00 x 10-2 M, pH = 3.03, I = 0.30 M and T =
25.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
At
0.1000
0.1102
0.1200
0.1294
0.1371
0.1436
0.1502
0.1548
0.1593
A8
0.1887
0.1887
0.1887
0.1887
0.1887
0.1887
0.1887
0.1887
0.1887
A8 - At
0.0887
0.0785
0.0687
0.0593
0.0516
0.0451
0.0385
0.0339
0.0294
ϴϳ
-ln(A8 - At)
2.42
2.54
2.68
2.83
2.96
3.10
3.26
3.38
3.53
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
540
600
660
720
0.1634
0.1669
0.1698
0.1725
0.1887
0.1887
0.1887
0.1887
0.0253
0.0218
0.0189
0.0162
3.68
3.83
3.97
4.12
Table 4.A.57. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-2 M, pH = 3.03, I = 0.30 M and T =
25.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
660
720
At
0.1110
0.1164
0.1283
0.1363
0.1438
0.1494
0.1547
0.1589
0.1629
0.1665
0.1698
0.1724
0.1747
A8
0.1891
0.1891
0.1891
0.1891
0.1891
0.1891
0.1891
0.1891
0.1891
0.1891
0.1891
0.1891
0.1891
A8 - At
0.0781
0.0727
0.0608
0.0528
0.0453
0.0397
0.0344
0.0302
0.0262
0.0226
0.0193
0.0167
0.0144
-ln(A8 - At)
2.55
2.62
2.80
2.94
3.09
3.23
3.37
3.50
3.64
3.79
3.95
4.09
4.24
Table 4.A.58. Summary table for the variation of kobs with [IO4?], at
[CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, I = 0.30 M, pH = 3.03 and T =
25.0 oC;
102[IO4?],
M
1/[IO4?],
103kobs, s-1
M-1
ϴϴ
1/kobs, s
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
0.20
1.77 ± 0.01
500.0
565.0
0.40
2.05 ± 0.01
250.0
487.8
0.80
2.25 ± 0.02
125.0
444.4
1.00
2.28 ± 0.02
100.0
438.6
3.00
2.39 ± 0.01
33.3
418.4
4.00
2.41 ± 0.02
25.0
414.9
4.A.4.2.2.3 Variation of [IO4?] at pH = 3.17
The kinetic data for the effect of IO4? on the rate of oxidation of [CrIII
(phen)2(H2O)2]3+ at T = 25 oC and pH = 3.17 are presented in Tables
4.A.59 – 4.A.65. Examples of first order fitting are represented in Figs.
4.18 – 4.22. The dependence of kobs on [IO4?] is summarized in Table
4.A.66. Plotting of 1/kobs vs 1/[IO4?], was found to be linear with an
intercept I1 and a slope S1 as shown in Fig. 4.27.
Table 4.A.59. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-3 M, pH = 3.17, I = 0.30 M and T =
25.0 oC;
Time/s
0
30
60
90
120
150
180
At
0.0932
0.1091
0.1143
0.1198
0.1256
0.1307
0.1357
A8
0.1958
0.1958
0.1958
0.1958
0.1958
0.1958
0.1958
A8 - At
0.1026
0.0867
0.0815
0.0760
0.0702
0.0651
0.0601
ϴϵ
-ln(A8 - At)
2.28
2.45
2.51
2.58
2.66
2.73
2.81
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
210
240
270
300
330
360
390
420
450
480
510
540
570
0.1394
0.1431
0.1459
0.1498
0.1528
0.1557
0.1580
0.1603
0.1631
0.1651
0.1672
0.1693
0.1708
0.1958
0.1958
0.1958
0.1958
0.1958
0.1958
0.1958
0.1958
0.1958
0.1958
0.1958
0.1958
0.1958
0.0564
0.0527
0.0499
0.0460
0.0430
0.0401
0.0378
0.0355
0.0327
0.0307
0.0286
0.0265
0.0250
2.88
2.94
3.00
3.08
3.15
3.22
3.28
3.34
3.42
3.48
3.55
3.63
3.69
Table 4.A.60. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 3.17, I = 0.30 M and T =
25.0 oC;
Time/s
0
30
60
90
120
150
180
210
240
At
0.1005
0.1124
0.1201
0.1265
0.1325
0.1371
0.1428
0.1461
0.1504
A8
0.1981
0.1981
0.1981
0.1981
0.1981
0.1981
0.1981
0.1981
0.1981
A8 - At
0.0976
0.0857
0.0780
0.0716
0.0656
0.0610
0.0553
0.0520
0.0477
ϵϬ
-ln(A8 - At)
2.33
2.46
2.55
2.64
2.72
2.80
2.89
2.96
3.04
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
270
300
330
360
390
420
450
480
0.1535
0.1575
0.1605
0.1635
0.1659
0.1686
0.1706
0.1727
0.1981
0.1981
0.1981
0.1981
0.1981
0.1981
0.1981
0.1981
0.0446
0.0406
0.0376
0.0346
0.0322
0.0295
0.0275
0.0254
3.11
3.20
3.28
3.36
3.44
3.52
3.59
3.67
3.50
3.00
-ln(A∞ - At)
2.50
2.00
1.50
1.00
0.50
0.00
0
100
200
300
400
500
time/s
Fig. 4.18. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 4.00 x 10-3
M, pH = 3.17, I = 0.30 M and T = 25.0 oC.
Table 4.A.61. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 8.00 x 10-3 M, pH = 3.17, I = 0.30 M and T =
25.0 oC;
Time/s
0
30
60
At
0.0756
0.0843
0.0931
A8
0.1736
0.1736
0.1736
A8 - At
0.0980
0.0893
0.0805
ϵϭ
-ln(A8 - At)
2.32
2.42
2.52
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
90
120
150
180
210
240
270
300
330
360
390
420
450
480
510
540
570
600
0.0995
0.1069
0.1118
0.1167
0.1218
0.1269
0.1303
0.1337
0.137
0.1404
0.1427
0.1451
0.1475
0.1496
0.1516
0.1535
0.1553
0.1569
0.1736
0.1736
0.1736
0.1736
0.1736
0.1736
0.1736
0.1736
0.1736
0.1736
0.1736
0.1736
0.1736
0.1736
0.1736
0.1736
0.1736
0.1736
0.0741
0.0667
0.0618
0.0569
0.0518
0.0467
0.0433
0.0399
0.0366
0.0332
0.0309
0.0285
0.0261
0.0240
0.0220
0.0201
0.0183
0.0167
2.60
2.71
2.78
2.87
2.96
3.06
3.14
3.22
3.31
3.41
3.48
3.56
3.65
3.73
3.82
3.91
4.00
4.09
4 .0 0
-ln(A∞ - At)
3 .0 0
2 .0 0
1 .0 0
0 .0 0
0
100
200
300
400
500
600
tim e /s
Fig. 4.19. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 8.00 x 10-3
M, pH = 3.17, I = 0.30 M and T = 25.0 oC.
Table 4.A.62. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 1.00 x 10-2 M, pH = 3.17, I = 0.30 M and T =
25.0 oC;
ϵϮ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Time/s
0
30
60
90
120
150
180
210
240
270
300
330
360
390
420
450
480
510
At
0.1180
0.1243
0.1335
0.1391
0.1457
0.1499
0.1551
0.1591
0.1635
0.1673
0.1700
0.1727
0.1754
0.1779
0.1802
0.1821
0.1839
0.1855
A8
0.2048
0.2048
0.2048
0.2048
0.2048
0.2048
0.2048
0.2048
0.2048
0.2048
0.2048
0.2048
0.2048
0.2048
0.2048
0.2048
0.2048
0.2048
A8 - At
0.0868
0.0805
0.0713
0.0657
0.0591
0.0549
0.0497
0.0457
0.0413
0.0375
0.0348
0.0321
0.0294
0.0269
0.0246
0.0227
0.0209
0.0193
4.00
-ln(A∞ - At)
3.00
2.00
1.00
0.00
0
100
200
300
400
time/s
ϵϯ
500
-ln(A8 - At)
2.44
2.52
2.64
2.72
2.83
2.90
3.00
3.09
3.19
3.28
3.36
3.44
3.53
3.62
3.71
3.79
3.87
3.95
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.20. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 1.00 x 10-2
M, pH = 3.17, I = 0.30 M and T = 25.0 oC.
Table 4.A.63. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-2 M, pH = 3.17, I = 0.30 M and T =
25.0 oC;
Time/s
0
30
60
90
120
150
180
210
240
270
300
330
360
390
420
450
480
510
540
570
At
0.1004
0.1071
0.1164
0.1229
0.1294
0.1350
0.1395
0.1435
0.1475
0.1521
0.1557
0.1583
0.1611
0.1638
0.1664
0.1679
0.1699
0.1719
0.1737
0.1751
A8
0.1908
0.1908
0.1908
0.1908
0.1908
0.1908
0.1908
0.1908
0.1908
0.1908
0.1908
0.1908
0.1908
0.1908
0.1908
0.1908
0.1908
0.1908
0.1908
0.1908
A8 - At
0.0904
0.0837
0.0744
0.0679
0.0614
0.0558
0.0513
0.0473
0.0433
0.0387
0.0351
0.0325
0.0297
0.0270
0.0244
0.0229
0.0209
0.0189
0.0171
0.0157
4.00
-ln(A∞ - At)
3.00
2.00
1.00
ϵϰ
0.00
0
100
200
300
time/s
400
500
600
-ln(A8 - At)
2.40
2.48
2.60
2.69
2.79
2.89
2.97
3.05
3.14
3.25
3.35
3.43
3.52
3.61
3.71
3.78
3.87
3.97
4.07
4.15
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.21. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 2.00 x 10-2
M, pH = 3.17, I = 0.30 M and T = 25.0 oC.
Table 4.A.64. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-2 M, pH = 3.17, I = 0.30 M and T =
25.0 oC;
Time/s
0
30
60
90
120
150
180
210
240
270
300
330
360
390
420
450
480
510
At
0.0893
0.0954
0.1035
0.1101
0.1167
0.1215
0.1252
0.1302
0.1342
0.1374
0.1405
0.1436
0.1467
0.1491
0.1515
0.1534
0.1555
0.1569
A8
0.1748
0.1748
0.1748
0.1748
0.1748
0.1748
0.1748
0.1748
0.1748
0.1748
0.1748
0.1748
0.1748
0.1748
0.1748
0.1748
0.1748
0.1748
A8 - At
0.0855
0.0794
0.0713
0.0647
0.0581
0.0533
0.0496
0.0446
0.0406
0.0374
0.0343
0.0312
0.0281
0.0257
0.0233
0.0214
0.0193
0.0179
4.00
-ln(A∞ - At)
3.00
2.00
1.00
ϵϱ
-ln(A8 - At)
2.46
2.53
2.64
2.74
2.85
2.93
3.00
3.11
3.20
3.29
3.37
3.47
3.57
3.66
3.76
3.84
3.95
4.02
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.22. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate ion at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 4.00 x
10-2 M, pH = 3.17, I = 0.30 M and T = 25.0 oC.
Table 4.A.65. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 5.00 x 10-2 M, pH = 3.17, I = 0.30 M and T =
25.0 oC;
Time/s
0
30
60
90
120
150
180
210
240
270
300
330
360
390
420
At
0.1243
0.1325
0.1397
0.1455
0.1494
0.1547
0.1581
0.1618
0.1656
0.1688
0.1711
0.1733
0.1754
0.1777
0.1796
A8
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
A8 - At
0.0748
0.0666
0.0594
0.0536
0.0497
0.0444
0.0410
0.0373
0.0335
0.0303
0.0280
0.0258
0.0237
0.0214
0.0195
ϵϲ
-ln(A8 - At)
2.59
2.71
2.82
2.93
3.00
3.11
3.19
3.29
3.40
3.50
3.58
3.66
3.74
3.84
3.94
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.66. Summary table for the variation of kobs with [IO4?], at
[CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, I = 0.30 M, pH = 3.17 and T =
25.0 oC;
102[IO4?],
M
0.20
0.40
0.80
1.00
2.00
4.00
5.00
1/[IO4?], M103kobs, s-1
2.31 ± 0.02
2.68 ± 0.02
2.90 ± 0.02
2.95 ± 0.02
3.06 ± 0.01
3.09 ± 0.02
3.11 ± 0.03
1
500
250
125
100
50
25
20
1/kobs, s
432.9
373.1
344.8
339.0
326.8
323.6
321.5
4.A.4.2.2.4 Variation of [IO4?] at pH = 3.45
The kinetic data for the effect of IO4? on the rate of oxidation of [CrIII
(phen)2(H2O)2]3+ at T = 25 oC and pH = 3.45 are shown in Tables
4.A.67 – 4.A.72 and the first order fitting represented as in Fig. 4.23.
The dependence of kobs on [IO4?] is summarized in Table 4.A.73.
Plotting of 1/kobs vs 1/[IO4?], was found to be linear with an intercept I1
and a slope S1 as shown in Fig. 4.27.
Table 4.A.67. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-3 M, pH = 3.45, I = 0.30 M and T =
25.0 oC;
Time/s
0
30
At
0.0926
0.1051
A8
0.1857
0.1857
A8 - At
0.0931
0.0806
ϵϳ
-ln(A8 - At)
2.37
2.52
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
60
90
120
150
180
210
240
270
300
330
0.1141
0.1220
0.1286
0.1347
0.1408
0.1447
0.1486
0.1520
0.1555
0.1585
0.1857
0.1857
0.1857
0.1857
0.1857
0.1857
0.1857
0.1857
0.1857
0.1857
0.0716
0.0637
0.0571
0.0510
0.0449
0.0410
0.0371
0.0337
0.0302
0.0272
2.64
2.75
2.86
2.98
3.10
3.19
3.29
3.39
3.50
3.60
3.20
-ln(A∞ - At)
2.40
1.60
0.80
0.00
0
100
200
300
400
time/t
Fig. 4.23. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 2.00 x 10-3
M, pH = 3.45, I = 0.30 M and T = 25.0 oC.
Table 4.A.68. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 3.45, I = 0.30 M and T =
25.0 oC;
Time/s
0
At
0.0963
A8
0.1869
A8 - At
0.0906
ϵϴ
-ln(A8 - At)
2.40
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
30
60
90
120
150
180
210
240
270
300
330
360
390
0.1078
0.1193
0.1261
0.1333
0.1392
0.1456
0.1502
0.1547
0.1582
0.1617
0.1645
0.1670
0.1689
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.1869
0.0791
0.0676
0.0608
0.0536
0.0477
0.0413
0.0367
0.0322
0.0287
0.0252
0.0224
0.0199
0.0180
2.54
2.69
2.80
2.93
3.04
3.19
3.30
3.44
3.55
3.68
3.80
3.92
4.02
Table 4.A.69. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 8.00 x 10-3 M, pH = 3.45, I = 0.30 M and T =
25.0 oC;
Time/s
0
30
60
90
120
150
180
210
240
270
300
330
At
0.1122
0.1243
0.1353
0.1426
0.1492
0.1551
0.1605
0.1648
0.1688
0.1722
0.1756
0.1786
A8
0.1972
0.1972
0.1972
0.1972
0.1972
0.1972
0.1972
0.1972
0.1972
0.1972
0.1972
0.1972
A8 - At
0.0850
0.0729
0.0619
0.0546
0.0480
0.0421
0.0367
0.0324
0.0284
0.0250
0.0216
0.0186
ϵϵ
-ln(A8 - At)
2.47
2.62
2.78
2.91
3.04
3.17
3.30
3.43
3.56
3.69
3.84
3.98
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.70. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 1.00 x 10-2 M, pH = 3.45, I = 0.30 M and T =
25.0 oC;
Time/s
0
30
60
90
120
150
180
210
240
270
300
330
360
At
0.1018
0.1156
0.1285
0.1377
0.1459
0.1525
0.1581
0.1637
0.1681
0.1711
0.1742
0.1779
0.1800
A8
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
A8 - At
0.0966
0.0828
0.0699
0.0607
0.0525
0.0459
0.0403
0.0347
0.0303
0.0273
0.0242
0.0205
0.0184
-ln(A8 - At)
2.34
2.49
2.66
2.80
2.95
3.08
3.21
3.36
3.50
3.60
3.72
3.89
4.00
Table 4.A.71. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-2 M, pH = 3.45, I = 0.30 M and T =
25.0 oC;
Time/s
0
30
60
90
120
150
180
210
At
0.1105
0.1282
0.1391
0.1477
0.1557
0.1617
0.1678
0.1722
A8
0.2053
0.2053
0.2053
0.2053
0.2053
0.2053
0.2053
0.2053
A8 - At
0.0948
0.0771
0.0662
0.0576
0.0496
0.0436
0.0375
0.0331
ϭϬϬ
-ln(A8 - At)
2.36
2.56
2.72
2.85
3.00
3.13
3.28
3.41
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
240
270
300
330
0.1763
0.1801
0.1835
0.1865
0.2053
0.2053
0.2053
0.2053
0.029
0.0252
0.0218
0.0188
3.54
3.68
3.83
3.97
Table 4.A.72. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 3.00 x 10-2 M, pH = 3.45, I = 0.30 M and T =
25.0 oC;
Time/s
0
30
60
90
120
150
180
210
240
270
300
330
At
0.1003
0.1098
0.1204
0.1298
0.1382
0.1448
0.1507
0.1554
0.1598
0.1639
0.1672
0.1701
A8
0.1893
0.1893
0.1893
0.1893
0.1893
0.1893
0.1893
0.1893
0.1893
0.1893
0.1893
0.1893
A8 - At
0.0890
0.0795
0.0689
0.0595
0.0511
0.0445
0.0386
0.0339
0.0295
0.0254
0.0221
0.0192
-ln(A8 - At)
2.42
2.53
2.68
2.82
2.97
3.11
3.25
3.38
3.52
3.67
3.81
3.95
Table 4.A.73. Summary table for the variation of kobs with [IO4?], at
[CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, I = 0.30 M, pH = 3.45 and T =
25.0 oC;
102[IO4?],
M
0.20
103kobs, s-1
3.60 ±
0.01
1/[IO4?],
M-1
1/kobs, s
500.0
277.78
ϭϬϭ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
0.40
0.80
1.00
2.00
3.00
4.12 ±
0.01
4.45 ±
0.01
4.51 ±
0.01
4.64 ±
0.01
4.72 ±
0.01
250.0
242.72
125.0
224.72
100.0
221.73
50.0
215.52
33.3
211.86
4.A.4.2.2.5 Variation of [IO4?] at pH = 3.74
The kinetic data for the effect of IO4? on the rate of oxidation of [CrIII
(phen)2(H2O)2]3+ at T = 25 oC and pH = 3.74 are presented in Tables
4.A.74 – 4.A.81. An example for first order fitting is represented in
Fig. 4.24. The dependence of kobs on [IO4?] is summarized in Table
4.A.82. Plotting of 1/kobs vs 1/[IO4?], was found to be linear with an
intercept I1 and a slope S1 as shown in Fig. 4.27.
Table 4.A.74 Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-3 M, pH = 3.74, I = 0.30 M and T =
25.0 oC;
Time/s
0
60
120
180
240
At
0.0509
0.0781
0.1031
0.1257
0.1429
A8
0.1923
0.1923
0.1923
0.1923
0.1923
A8 - At
0.1414
0.1142
0.0892
0.0666
0.0494
ϭϬϮ
-ln(A8 - At)
1.96
2.17
2.42
2.71
3.01
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
300
360
420
480
540
600
660
0.1555
0.1649
0.1721
0.1771
0.1811
0.1839
0.1860
0.1923
0.1923
0.1923
0.1923
0.1923
0.1923
0.1923
0.0368
0.0274
0.0202
0.0152
0.0112
0.0084
0.0063
3.30
3.60
3.90
4.19
4.49
4.78
5.07
5.00
-ln(A∞ - At)
4.00
3.00
2.00
1.00
0.00
0
100
200
300
400
500
600
700
time/s
Fig. 4.14. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate ion at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 2.00 x
10-3 M, pH = 3.74, I = 0.30 M and T = 25.0 oC.
Table 4.A.75. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 3.74, I = 0.30 M and T =
25.0 oC;
Time/s
0
60
120
180
At
0.0471
0.0711
0.1048
0.1296
A8
0.1933
0.1933
0.1933
0.1933
A8 - At
0.1432
0.1222
0.0885
0.0637
ϭϬϯ
-ln(A8 - At)
1.94
2.10
2.42
2.75
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
240
300
360
420
480
540
600
0.1475
0.1609
0.1699
0.1769
0.1815
0.1846
0.1870
0.1933
0.1933
0.1933
0.1933
0.1933
0.1933
0.1933
0.0458
0.0324
0.0234
0.0164
0.0118
0.0087
0.0063
3.08
3.43
3.76
4.11
4.44
4.74
5.07
Table 4.A.76. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 6.00 x 10-3 M, pH = 3.74, I = 0.30 M and T =
25.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
At
0.0703
0.099
0.1219
0.1444
0.1587
0.1698
0.1773
0.1824
0.1862
0.1885
A8
0.1948
0.1948
0.1948
0.1948
0.1948
0.1948
0.1948
0.1948
0.1948
0.1948
A8 - At
0.1245
0.0958
0.0729
0.0504
0.0361
0.0250
0.0175
0.0124
0.0086
0.0063
ϭϬϰ
-ln(A8 - At)
2.08
2.35
2.62
2.99
3.32
3.69
4.05
4.39
4.76
5.07
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.77. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 8.00 x 10-3 M, pH = 3.74, I = 0.30 M and T =
25.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
At
0.0507
0.0705
0.1026
0.1296
0.1475
0.1609
0.1707
0.1776
0.1825
0.1856
0.1877
A8
0.1928
0.1928
0.1928
0.1928
0.1928
0.1928
0.1928
0.1928
0.1928
0.1928
0.1928
A8 - At
0.1421
0.1223
0.0902
0.0632
0.0453
0.0319
0.0221
0.0152
0.0103
0.0072
0.0051
-ln(A8 - At)
1.95
2.10
2.41
2.76
3.09
3.45
3.81
4.19
4.58
4.93
5.28
Table 4.A.78. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 1.00 x 10-2 M, pH = 3.74, I = 0.30 M and T =
25.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
At
0.0529
0.0725
0.1021
0.1282
0.1472
0.1619
0.1711
0.1774
0.1821
0.1852
0.1873
A8
0.1921
0.1921
0.1921
0.1921
0.1921
0.1921
0.1921
0.1921
0.1921
0.1921
0.1921
A8 - At
0.1392
0.1196
0.0900
0.0639
0.0449
0.0302
0.0210
0.0147
0.0100
0.0069
0.0048
ϭϬϱ
-ln(A8 - At)
1.97
2.12
2.41
2.75
3.10
3.50
3.86
4.22
4.61
4.98
5.34
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.79. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-2 M, pH = 3.74, I = 0.30 M and T =
25.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
At
0.0521
0.0776
0.1062
0.1337
0.1529
0.1649
0.1738
0.1799
0.1837
0.1865
0.1883
A8
0.1925
0.1925
0.1925
0.1925
0.1925
0.1925
0.1925
0.1925
0.1925
0.1925
0.1925
A8 - At
0.1404
0.1149
0.0863
0.0588
0.0396
0.0276
0.0187
0.0126
0.0088
0.0060
0.0042
-ln(A8 - At)
1.96
2.16
2.45
2.83
3.23
3.59
3.98
4.37
4.73
5.12
5.47
Table 4.A.80. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 3.00 x 10-2 M, pH = 3.74, I = 0.30 M and T =
25.0 oC;
Time/s
0
60
120
180
240
At
0.0502
0.0783
0.1082
0.1345
0.1537
A8
0.1920
0.1920
0.1920
0.1920
0.1920
A8 - At
0.1418
0.1137
0.0838
0.0575
0.0383
ϭϬϲ
-ln(A8 - At)
1.95
2.17
2.48
2.86
3.26
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
300
360
420
480
540
600
0.1658
0.1741
0.1799
0.1836
0.1863
0.1882
0.1920
0.1920
0.1920
0.1920
0.1920
0.1920
0.0262
0.0179
0.0121
0.0084
0.0057
0.0038
3.64
4.02
4.41
4.78
5.17
5.57
Table 4.A.81. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-2 M, pH = 3.74, I = 0.30 M and T =
25.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
At
0.0526
0.0855
0.1169
0.1399
0.1566
0.1676
0.1759
0.1809
0.1848
0.1872
0.1889
A8
0.1924
0.1924
0.1924
0.1924
0.1924
0.1924
0.1924
0.1924
0.1924
0.1924
0.1924
A8 - At
0.1368
0.1049
0.0755
0.0525
0.0358
0.0248
0.0165
0.0115
0.0077
0.0052
0.0034
-ln(A8 - At)
1.99
2.25
2.58
2.95
3.33
3.70
4.10
4.47
4.87
5.26
5.68
Table 4.A.82. Summary table for the variation of kobs with [IO4?], at
[CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, I = 0.30 M, pH = 3.74 and T =
25.0 oC;
102[IO4?],
103kobs, s-1
1/[IO4?],
ϭϬϳ
1/kobs, s
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
M
0.20
0.40
0.60
0.80
1.00
2.00
3.00
4.00
4.89 ± 0.04
5.53 ± 0.02
5.79 ± 0.06
5.96 ± 0.08
6.05 ± 0.06
6.24 ± 0.07
6.35 ± 0.08
6.36 ± 0.06
M-1
500.0
250.0
166.7
125.0
100.0
50.0
33.3
25.0
204.5
180.8
172.7
167.8
165.3
160.3
157.5
157.2
4.A.4.2.2.6 Variation of [IO4?] at pH = 4.39
The kinetic data for the effect of IO4? on the rate of oxidation of [CrIII
(phen)2(H2O)2]3+ at T = 25 oC and pH = 4.39 are shown in Tables
4.A.83 – 4.A.88. Examples of first order fitting are shown in Figs. 4.25
– 4.26. The dependence of kobs on [IO4?] is summarized in Table
4.A.89. Plotting of 1/kobs vs 1/[IO4?], was found to be linear with an
intercept I1 and a slope S1 as shown in Fig. 4.27.
Table 4.A.83. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-3 M, pH = 4.39, I = 0.30 M and T =
25.0 oC;
Time/s
0
40
80
120
160
200
At
0.0528
0.0788
0.1058
0.1267
0.1453
0.1574
A8
0.1937
0.1937
0.1937
0.1937
0.1937
0.1937
A8 - At
0.1409
0.1149
0.0879
0.0670
0.0484
0.0363
ϭϬϴ
-ln(A8 - At)
1.96
2.16
2.43
2.70
3.03
3.32
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
240
280
320
360
400
440
480
0.1669
0.1738
0.1791
0.1831
0.1859
0.1881
0.1896
0.1937
0.1937
0.1937
0.1937
0.1937
0.1937
0.1937
0.0268
0.0199
0.0146
0.0106
0.0078
0.0056
0.0041
3.62
3.92
4.23
4.55
4.85
5.18
5.50
6.00
5.00
-ln(A∞ -At)
4.00
3.00
2.00
1.00
0.00
0
100
200
300
400
500
time/s
Fig. 4.25. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate ion at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 2.00 x
10-3 M, pH = 4.39, I = 0.30 M and T = 25.0 oC.
Table 4.A.84. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 4.39, I = 0.30 M and T =
25.0 oC;
Time/s
0
At
0.1285
A8
0.2237
A8 - At
0.0952
ϭϬϵ
-ln(A8 - At)
2.35
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
320
0.1452
0.1579
0.1685
0.1764
0.1843
0.1904
0.1951
0.1995
0.2033
0.2066
0.2088
0.2113
0.2132
0.2146
0.2159
0.2170
0.2237
0.2237
0.2237
0.2237
0.2237
0.2237
0.2237
0.2237
0.2237
0.2237
0.2237
0.2237
0.2237
0.2237
0.2237
0.2237
0.0785
0.0658
0.0552
0.0473
0.0394
0.0333
0.0286
0.0242
0.0204
0.0171
0.0149
0.0124
0.0105
0.0091
0.0078
0.0067
2.54
2.72
2.90
3.05
3.23
3.40
3.55
3.72
3.89
4.07
4.21
4.39
4.56
4.70
4.85
5.01
5.00
-ln(A∞ - At)
4.00
3.00
2.00
1.00
0.00
0
50
100
150
200
250
300
350
time/s
Fig.4.26. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate ion at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 4.00 x
10-3 M, pH = 4.39, I = 0.30 M and T = 25.0 oC.
ϭϭϬ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.85. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 8.00 x 10-3 M, pH = 4.39, I = 0.30 M and T =
25.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
At
0.1359
0.1526
0.1649
0.1733
0.1799
0.1852
0.1899
0.1949
0.1983
0.2006
0.2031
0.2053
0.2072
0.2087
0.2099
A8
0.2166
0.2166
0.2166
0.2166
0.2166
0.2166
0.2166
0.2166
0.2166
0.2166
0.2166
0.2166
0.2166
0.2166
0.2166
A8 - At
0.0807
0.0640
0.0517
0.0433
0.0367
0.0314
0.0267
0.0217
0.0183
0.0160
0.0135
0.0113
0.0094
0.0079
0.0067
-ln(A8 - At)
2.52
2.75
2.96
3.14
3.30
3.46
3.62
3.83
4.00
4.14
4.31
4.48
4.67
4.84
5.01
Table 4.A.86. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 1.00 x 10-2 M, pH = 4.39, I = 0.30 M and T =
25.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
At
0.0621
0.0809
0.0967
0.1133
0.1277
0.1376
0.1481
0.1569
0.1638
A8
0.2003
0.2003
0.2003
0.2003
0.2003
0.2003
0.2003
0.2003
0.2003
A8 - At
0.1142
0.1194
0.1036
0.0870
0.0726
0.0627
0.0522
0.0434
0.0365
ϭϭϭ
-ln(A8 - At)
2.17
2.13
2.27
2.44
2.62
2.77
2.95
3.14
3.31
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
180
0.1696
0.2003
0.0307
3.48
200
0.1742
0.2003
0.0261
3.65
220
0.1785
0.2003
0.0218
3.83
240
0.1823
0.2003
0.0180
4.02
260
0.1848
0.2003
0.0155
4.17
280
0.1873
0.2003
0.0130
4.34
300
0.1894
0.2003
0.0109
4.52
Table 4.A.87. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-2 M, pH = 4.39, I = 0.30 M and T =
25.0 oC;
Time/s
At
A8
A8 - At
-ln(A8 - At)
0
0.1277
0.2095
0.0818
2.50
20
0.1409
0.2095
0.0686
2.68
40
0.1521
0.2095
0.0574
2.86
60
0.1612
0.2095
0.0483
3.03
80
0.1686
0.2095
0.0409
3.20
100
0.1753
0.2095
0.0342
3.38
120
0.1815
0.2095
0.028
3.58
140
0.1859
0.2095
0.0236
3.75
160
0.1891
0.2095
0.0204
3.89
Table 4.A.88. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-2 M, pH = 4.39, I = 0.30 M and T =
25.0 oC;
Time/s
0
20
40
At
0.1511
0.1624
0.1733
A8
0.2337
0.2337
0.2337
A8 - At
0.0826
0.0713
0.0604
ϭϭϮ
-ln(A8 - At)
2.49
2.64
2.81
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
60
80
100
120
140
160
180
200
220
0.1857
0.1928
0.1989
0.2044
0.2089
0.2130
0.2164
0.2194
0.2219
0.2337
0.2337
0.2337
0.2337
0.2337
0.2337
0.2337
0.2337
0.2337
0.0480
0.0409
0.0348
0.0293
0.0248
0.0207
0.0173
0.0143
0.0118
3.04
3.20
3.36
3.53
3.70
3.88
4.06
4.25
4.44
Table 4.A.89. Summary table for the variation of kobs with [IO4?], at
[CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, I = 0.30 M, pH = 4.39 and T =
25.0 oC;
102[IO4?],
M
0.20
0.40
0.80
1.00
2.00
4.00
103kobs, s-1
7.62 ± 0.05
8.22 ± 0.04
8.56 ± 0.01
8.63 ± 0.06
8.78 ± 0.10
8.87 ± 0.10
1/[IO4?],
M-1
500
250
125
100
50
25
1/kobs, s
131.23
121.65
116.82
115.87
113.90
112.74
Table 4.A.90. Values of intercepts and slopes at 25.0 oC and various
pH values obtained from plots of kobs-1 versus [IO4?]-1;
pH
104[H+] M
2.81
3.01
3.17
15.49
9.77
6.76
102S1, M
50.00 ±
0.10
31.70 ± 0.01
23.20 ± 0.10
ϭϭϯ
10-2I1, s
5.67 ± 0.03
4.07 ± 0.02
3.16 ± 0.02
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
3.45
3.74
4.39
3.54
1.82
0.41
14.00 ± 0.04
10.00 ± 0.04
3.87 ± 0.01
2.08 ± 0.01
1.55 ± 0.01
1.11 ± 0.01
800
A
700
600
B
1/kobs, s
500
C
400
300
D
E
200
F
100
0
0
100
200
300
−
400
500
-1
1/[IO4 ], M
Fig. 4.27. Plots of kobs-1 versus [IO4?]-1 at pH values, (A) 2.81, (B)
3.01, (C) 3.17 (D) 3.45, (E) 3.74 and (F) 4.39 at 25.0 oC.
50.0
30.0
2
10 S1, M
40.0
20.0
10.0
0.0
0.0
2.0
4.0
6.0
8.0
4
10.0
12.0
14.0
16.0
+
10 [H ], M
Fig. 4.28. Dependence of S1 on [H+] at 25 oC.
6.0
5.0
-2
10 I1, s
4.0
3.0
2.0
1.0
ϭϭϰ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.29. Dependence of I1 on [H+] at 25 oC.
Table 4.A.91. Values of I2, S2 and I3 S3 at 25 oC obtained from plots of
I1 vs [H+] and S1 vs [H+], respectively;
I2 = 102.0 ± 4.4
S2 = (304.82 ± 5.42) x 10-3
I3 = (33.56 ± 5.50) x
S3 = 298.0 ± 6.8
103
4.A.4.2.3 Variation of [IO4?] at 30.0 oC
Under fixed reaction conditions, the effect of IO4? on the rate of
oxidation of [CrIII(phen)2(H2O)2]3+ was investigated. The pH was
varied from 2.51 – 3.65. Values of intercepts I1 and slope S1 at various
pH values are summarized in Table 4.A.127. Values of intercepts (I2
and I3) and slopes (S2 and S3) at various pH values obtained from plots
of I1 against [H+], Fig. 4.38 and S1 against [H+], Fig. 4.39, are shown in
Table 4.A.128.
ϭϭϱ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
4.A.4.2.3.1 Variation of [IO4?] at pH = 2.51
The kinetic data for the effect of IO4? on the rate of oxidation of [CrIII
(phen)2(H2O)2]3+ at T = 30 oC and pH = 2.51 are collected in Tables
4.A.92 – 4.A.97. A first order fitting represented as in Fig. 4.30. The
dependence of kobs on [IO4?] is summarized in Table 4.A.98. Plotting
of 1/kobs vs 1/[IO4?], was found to be linear with an intercept I1 and a
slope S1 as shown in Fig. 4.37.
Table 4.A.92. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-3 M, pH = 2.51, I = 0.30 M and T =
30.0 oC;
Time/s
0
120
240
360
480
600
720
840
960
1080
1200
1320
1440
At
0.0668
0.0846
0.0942
0.1031
0.1104
0.1177
0.1243
0.1300
0.1344
0.1397
0.1443
0.1481
0.1523
A8
0.1965
0.1965
0.1965
0.1965
0.1965
0.1965
0.1965
0.1965
0.1965
0.1965
0.1965
0.1965
0.1965
A8 - At
0.1297
0.1119
0.1023
0.0934
0.0861
0.0788
0.0722
0.0665
0.0621
0.0568
0.0522
0.0484
0.0442
ϭϭϲ
-ln(A8 - At)
2.04
2.19
2.28
2.37
2.45
2.54
2.63
2.71
2.78
2.87
2.95
3.03
3.12
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
3.00
2.50
-ln(A∞ - At)
2.00
1.50
1.00
0.50
0.00
0
400
800
1200
1600
time/s
Fig. 4.30. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate ion at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 2.00 x
10-3 M, pH = 2.51, I = 0.30 M and T = 30.0 oC.
Table 4.A.93. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 2.51, I = 0.30 M and T =
30.0 oC;
Time/s
0
120
240
360
480
600
720
840
960
1080
1200
1320
1440
At
0.0681
0.0899
0.1004
0.1102
0.1181
0.1254
0.1325
0.1383
0.1433
0.1482
0.1536
0.1575
0.1609
A8
0.1968
0.1968
0.1968
0.1968
0.1968
0.1968
0.1968
0.1968
0.1968
0.1968
0.1968
0.1968
0.1968
ϭϭϳ
A8 - At
0.1287
0.1069
0.0964
0.0866
0.0787
0.0714
0.0643
0.0585
0.0535
0.0486
0.0432
0.0393
0.0359
-ln(A8 - At)
2.05
2.24
2.34
2.45
2.54
2.64
2.74
2.84
2.93
3.02
3.14
3.24
3.33
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.94. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 8.00 x 10-3 M, pH = 2.51, I = 0.30 M and T =
30.0 oC;
Time/s
0
120
240
360
480
600
720
840
960
1080
1200
1320
At
0.0633
0.0813
0.0927
0.1037
0.1138
0.1219
0.1299
0.1369
0.1436
0.1488
0.1535
0.1571
A8
0.1966
0.1966
0.1966
0.1966
0.1966
0.1966
0.1966
0.1966
0.1966
0.1966
0.1966
0.1966
A8 - At
0.1333
0.1153
0.1039
0.0929
0.0828
0.0747
0.0667
0.0597
0.053
0.0478
0.0431
0.0395
-ln(A8 - At)
2.02
2.16
2.26
2.38
2.49
2.59
2.71
2.82
2.94
3.04
3.14
3.23
Table 4.A.95. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 1.00 x 10-2 M, pH = 2.51, I = 0.30 M and T =
30.0 oC;
Time/s
0
120
240
360
At
0.0765
0.0912
0.1031
0.1127
A8
0.1964
0.1964
0.1964
0.1964
A8 - At
0.1199
0.1052
0.0933
0.0837
ϭϭϴ
-ln(A8 - At)
2.12
2.25
2.37
2.48
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
480
600
720
840
960
1080
1200
1320
0.1219
0.1308
0.1367
0.1436
0.1489
0.1538
0.1578
0.1618
0.1964
0.1964
0.1964
0.1964
0.1964
0.1964
0.1964
0.1964
0.0745
0.0656
0.0597
0.0528
0.0475
0.0426
0.0386
0.0346
2.60
2.72
2.82
2.94
3.05
3.16
3.25
3.36
Table 4.A.96. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-2 M, pH = 2.51, I = 0.30 M and T =
30.0 oC;
Time/s
0
120
240
360
480
600
720
840
960
1080
1200
1320
At
0.0718
0.0901
0.1021
0.1123
0.1219
0.1298
0.1368
0.1437
0.1493
0.1545
0.1591
0.1626
A8
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
A8 - At
0.1244
0.1061
0.0941
0.0839
0.0743
0.0664
0.0594
0.0525
0.0469
0.0417
0.0371
0.0336
-ln(A8 - At)
2.08
2.24
2.36
2.48
2.60
2.71
2.82
2.95
3.06
3.18
3.29
3.39
Table 4.A.97. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 4.00 x 10-2 M, pH = 2.51, I = 0.30 M and T =
30.0 oC;
ϭϭϵ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Time/s
0
120
240
360
480
600
720
840
960
1080
1200
1320
At
0.0784
0.0934
0.1047
0.1157
0.1251
0.1326
0.1398
0.1462
0.1514
0.1566
0.1608
0.1647
A8
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
0.1962
A8 - At
0.1178
0.1028
0.0915
0.0805
0.0711
0.0636
0.0564
0.0500
0.0448
0.0396
0.0354
0.0315
-ln(A8 - At)
2.14
2.27
2.39
2.52
2.64
2.76
2.88
3.00
3.11
3.23
3.34
3.46
Table 4.A.98. Summary table for the variation of kobs with [IO4?], at
[CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, I = 0.30 M, pH = 2.51 and T =
30.0 oC;
102[IO4?],
M
0.20
0.40
0.80
1.00
2.00
4.00
104kobs, s-1
7.00
8.25
9.08
9.27
9.64
9.85
1/[IO4?],
M-1
500
250
125
100
50
25
1/kobs, s
1428.6
1212.1
1101.3
1078.7
1037.3
1015.2
4.A.4.2.3.2 Variation of [IO4?] at pH = 2.70
The kinetic data for the effect of IO4? on the rate of oxidation of [CrIII
(phen)2(H2O)2]3+ at T = 30 oC and pH = 2.70 are collected in Tables
ϭϮϬ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
4.A.99 – 4.A.104. and the first order fitting represented as in Fig. 4.31.
The dependence of kobs on [IO4?] is summarized in Table 4.A.105.
Plotting of 1/kobs vs 1/[IO4?], was found to be linear with an intercept I1
and a slope S1 as shown in Fig. 4.37.
Table 4.A.99. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, [IO4?] = 2.00 x 10-3 M, pH = 2.70, I = 0.30 M and T =
30.0 oC;
Time/s
At
A8
A8 - At
-ln(A8 - At)
0
0.1091
0.1992
0.0901
2.41
60
0.1205
0.1992
0.0787
2.54
120
0.1255
0.1992
0.0737
2.61
180
0.1309
0.1992
0.0683
2.68
240
0.1352
0.1992
0.0640
2.75
300
0.1399
0.1992
0.0593
2.83
360
0.1431
0.1992
0.0561
2.88
420
0.1462
0.1992
0.0530
2.94
480
0.1488
0.1992
0.0504
2.99
540
0.152
0.1992
0.0472
3.05
600
0.1545
0.1992
0.0447
3.11
660
0.1572
0.1992
0.0420
3.17
720
0.1595
0.1992
0.0397
3.23
780
0.1621
0.1992
0.0371
3.29
III
Table 4.A.100. Kinetic data for the reaction at [Cr (phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 2.70, I = 0.30 M and T =
30.0 oC;
Time/s
0
60
120
180
At
0.1161
0.1211
0.1283
0.1332
A8
0.1988
0.1988
0.1988
0.1988
A8 - At
0.0827
0.0777
0.0705
0.0656
ϭϮϭ
-ln(A8 - At)
2.49
2.55
2.65
2.72
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
240
300
360
420
480
540
600
660
720
780
0.1379
0.1417
0.1457
0.1497
0.1534
0.1568
0.1595
0.1617
0.1648
0.1669
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.0609
0.0571
0.0531
0.0491
0.0454
0.0420
0.0393
0.0371
0.0340
0.0319
2.80
2.86
2.94
3.01
3.09
3.17
3.24
3.29
3.38
3.45
Table 4.A.101. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 8.00 x 10-3 M, pH = 2.70, I = 0.30 M and T =
30.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
660
720
At
0.0758
0.1082
0.1164
0.1227
0.1296
0.1344
0.1391
0.1444
0.1477
0.1521
0.1556
0.1587
0.1619
A8
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
A8 - At
0.1240
0.0916
0.0834
0.0771
0.0702
0.0654
0.0607
0.0554
0.0521
0.0477
0.0442
0.0411
0.0379
ϭϮϮ
-ln(A8 - At)
2.09
2.39
2.48
2.56
2.66
2.73
2.80
2.89
2.95
3.04
3.12
3.19
3.27
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.102. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 1.00 x 10-2 M, pH = 2.70, I = 0.30 M and T =
30.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
660
720
780
At
0.0907
0.1053
0.1135
0.1212
0.1273
0.1332
0.1378
0.1420
0.1472
0.1513
0.1545
0.1582
0.1615
0.1642
A8
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
A8 - At
0.1091
0.0945
0.0863
0.0786
0.0725
0.0666
0.0620
0.0578
0.0526
0.0485
0.0453
0.0416
0.0383
0.0356
-ln(A8 - At)
2.22
2.36
2.45
2.54
2.62
2.71
2.78
2.85
2.95
3.03
3.09
3.18
3.26
3.34
Table 4.A.103. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 2.00 x 10-2 M, pH = 2.70, I = 0.30 M and T =
30.0 oC;
Time/s
0
60
120
180
240
300
360
420
At
0.0972
0.1243
0.1307
0.1369
0.1416
0.1464
0.1501
0.1545
A8
0.1997
0.1997
0.1997
0.1997
0.1997
0.1997
0.1997
0.1997
A8 - At
0.1025
0.0754
0.0690
0.0628
0.0581
0.0533
0.0496
0.0452
ϭϮϯ
-ln(A8 - At)
2.28
2.58
2.67
2.77
2.85
2.93
3.00
3.10
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
480
540
600
660
0.1581
0.1615
0.1646
0.1674
0.1997
0.1997
0.1997
0.1997
0.0416
0.0382
0.0351
0.0323
3.18
3.26
3.35
3.43
Table 4.A.104. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 4.00 x 10-2 M, pH = 2.70, I = 0.30 M and T =
30.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
660
720
780
At
0.0870
0.0926
0.1025
0.1126
0.1196
0.1257
0.1318
0.1372
0.1421
0.1466
0.1514
0.1554
0.1589
0.1621
A8
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
0.1998
A8 - At
0.1128
0.1072
0.0973
0.0872
0.0802
0.0741
0.0680
0.0626
0.0577
0.0532
0.0484
0.0444
0.0409
0.0377
-ln(A8 - At)
2.18
2.23
2.33
2.44
2.52
2.60
2.69
2.77
2.85
2.93
3.03
3.11
3.20
3.28
3.30
-ln(A∞ - At)
3.00
2.70
ϭϮϰ
2.40
2.10
0
200
400
time/s
600
800
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.31. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate ion at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 4.00 x
10-2 M, pH = 2.70, I = 0.30 M and T = 30.0 oC.
Table 4.A.105. Summary table for the variation of kobs with [IO4?], at
[CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, I = 0.30 M, pH = 2.70 and T =
30.0 oC;
102[IO4?],
M
0.20
0.40
0.80
1.00
2.00
4.00
1/[IO4?], M103kobs, s-1
1.02 ±
0.01
1.21 ±
0.01
1.32 ±
0.01
1.34 ±
0.01
1.40 ±
0.01
1.43 ±
0.01
1
1/kobs, s
500
980.4
250
826.4
125
757.6
100
746.3
50
714.3
25
699.3
4.A.4.2.3.3 Variation of [IO4?] at pH = 3.03
ϭϮϱ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
The kinetic data for the effect of IO4? on the rate of oxidation of [CrIII
(phen)2(H2O)2]3+ at T = 30 oC and pH = 3.03 are presented in Tables
4.A106 – 4.A.111. An example of a first order fitting is shown in Fig.
4.32. The dependence of kobs on [IO4?] is summarized in Table
4.A.112. Plotting of 1/kobs vs 1/[IO4?], was found to be linear with an
intercept I1 and a slope S1 as shown in Fig. 4.37.
Table 4.A.106. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 2.00 x 10-3 M, pH = 3.03, I = 0.30 M and T =
30.0 oC;
Time/s
0
30
60
90
120
150
180
210
240
270
300
330
360
At
0.0764
0.0991
0.1061
0.1119
0.1164
0.1209
0.1258
0.1299
0.1338
0.1374
0.1409
0.1441
0.1469
A8
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
A8 - At
0.1224
0.0997
0.0927
0.0869
0.0824
0.0779
0.0730
0.0689
0.0650
0.0614
0.0579
0.0547
0.0519
-ln(A8 - At)
2.10
2.31
2.38
2.44
2.50
2.55
2.62
2.68
2.73
2.79
2.85
2.91
2.96
Table 4.A.107. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 3.03, I = 0.30 M and T =
30.0 oC;
ϭϮϲ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Time/s
0
30
60
90
120
150
180
210
240
270
300
330
360
At
0.1000
0.1207
0.1267
0.1322
0.1356
0.1399
0.1437
0.1469
0.1505
0.1535
0.1568
0.1599
0.1619
A8
0.1983
0.1983
0.1983
0.1983
0.1983
0.1983
0.1983
0.1983
0.1983
0.1983
0.1983
0.1983
0.1983
A8 - At
0.0983
0.0776
0.0716
0.0661
0.0627
0.0584
0.0546
0.0514
0.0478
0.0448
0.0415
0.0384
0.0364
-ln(A8 - At)
2.32
2.56
2.64
2.72
2.77
2.84
2.91
2.97
3.04
3.11
3.18
3.26
3.31
Table 4.A.108. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 8.00 x 10-3 M, pH = 3.03, I = 0.30 M and T =
30.0 oC;
Time/s
0
30
60
90
120
150
180
210
240
270
300
330
360
At
0.0811
0.0988
0.1074
0.1138
0.1203
0.1253
0.1312
0.1361
0.1404
0.1446
0.1482
0.1520
0.1551
A8
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
A8 - At
0.1175
0.0998
0.0912
0.0848
0.0783
0.0733
0.0674
0.0625
0.0582
0.0540
0.0504
0.0466
0.0435
ϭϮϳ
-ln(A8 - At)
2.14
2.30
2.39
2.47
2.55
2.61
2.70
2.77
2.84
2.92
2.99
3.07
3.13
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.109. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 1.00 x 10-2 M, pH = 3.03, I = 0.30 M and T =
30.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
At
0.1123
0.1194
0.1235
0.1276
0.1312
0.1351
0.1381
0.1413
0.1446
0.1468
0.1492
0.1512
0.1539
0.1558
0.1584
0.1602
A8
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
A8 - At
0.0866
0.0795
0.0754
0.0713
0.0677
0.0638
0.0608
0.0576
0.0543
0.0521
0.0497
0.0477
0.0450
0.0431
0.0405
0.0387
-ln(A8 - At)
2.45
2.53
2.58
2.64
2.69
2.75
2.80
2.85
2.91
2.95
3.00
3.04
3.10
3.14
3.21
3.25
Table 4.A.110. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 2.00 x 10-2 M, pH = 3.03, I = 0.30 M and T =
30.0 oC;
Time/s
0
20
40
60
80
At
0.0836
0.0994
0.1060
0.1112
0.1148
A8
0.1988
0.1988
0.1988
0.1988
0.1988
A8 - At
0.1152
0.0994
0.0928
0.0876
0.0840
ϭϮϴ
-ln(A8 - At)
2.16
2.31
2.38
2.43
2.48
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
100
0.1191
0.1988
0.0797
2.53
120
0.1231
0.1988
0.0757
2.58
140
0.1275
0.1988
0.0713
2.64
160
0.1312
0.1988
0.0676
2.69
180
0.1349
0.1988
0.0639
2.75
200
0.1383
0.1988
0.0605
2.81
220
0.1406
0.1988
0.0582
2.84
240
0.1438
0.1988
0.0550
2.90
260
0.1466
0.1988
0.0522
2.95
280
0.1491
0.1988
0.0497
3.00
III
Table 4.A.111. Kinetic data for the reaction at [Cr (phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 4.00 x 10-2 M, pH = 3.03, I = 0.30 M and T =
30.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
At
0.1181
0.1292
0.1339
0.1373
0.1405
0.1438
0.1461
0.1491
0.1515
0.1543
0.1560
0.1583
0.1608
0.1629
0.1645
A8
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
A8 - At
0.0805
0.0694
0.0647
0.0613
0.0581
0.0548
0.0525
0.0495
0.0471
0.0443
0.0426
0.0403
0.0378
0.0357
0.0341
3.40
3.20
-ln(A∞ - At)
ϭϮϵ
3.00
2.80
-ln(A8 - At)
2.52
2.67
2.74
2.79
2.85
2.90
2.95
3.01
3.06
3.12
3.16
3.21
3.28
3.33
3.38
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.32. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 4.00 x 10-2
M, pH = 3.03, I = 0.30 M and T = 30.0 oC.
Table 4.A.112. Summary table for the variation of kobs with [IO4?], at
[CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, I = 0.30 M, pH = 3.03 and T =
30.0 oC;
102[IO4?],
M
0.20
0.40
0.80
1.00
2.00
4.00
103kobs, s-1
1.96 ± 0.01
2.28 ± 0.01
2.50 ± 0.02
2.55 ± 0.03
2.64 ± 0.03
2.69 ± 0.03
1/[IO4?],
M-1
500
250
125
100
50
25
1/kobs, s
510.2
438.6
400.0
392.2
378.8
371.7
4.A.4.2.3.4 Variation of [IO4?] at pH = 3.26
The kinetic data for the effect of IO4? on the rate of oxidation of [CrIII
(phen)2(H2O)2]3+ at pH = 3.26 are shown in Tables 4.A.113 – 4.A.118.
An example of the first order fitting is shown in Fig. 4.33. The
ϭϯϬ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
dependence of kobs on [IO4?] is summarized in Table 4.A.119. Plotting
of 1/kobs vs 1/[IO4?], was found to be linear with an intercept I1 and a
slope S1 as shown in Fig. 4.37.
Table 4.A.113. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 2.00 x 10-3 M, pH = 3.26, I = 0.30 M and T =
30.0 oC;
Time/s
At
A8
A8 - At
-ln(A8 - At)
0
0.1007
0.1979
0.0972
2.33
20
0.1144
0.1979
0.0835
2.48
40
0.1191
0.1979
0.0788
2.54
60
0.1233
0.1979
0.0746
2.60
80
0.1267
0.1979
0.0712
2.64
100
0.1322
0.1979
0.0657
2.72
120
0.1352
0.1979
0.0627
2.77
140
0.1387
0.1979
0.0592
2.83
160
0.1426
0.1979
0.0553
2.89
180
0.1456
0.1979
0.0523
2.95
200
0.1485
0.1979
0.0494
3.01
220
0.1521
0.1979
0.0458
3.08
240
0.1547
0.1979
0.0432
3.14
260
0.1569
0.1979
0.0410
3.19
280
0.1592
0.1979
0.0387
3.25
300
0.1613
0.1979
0.0366
3.31
III
Table 4.A.114. Kinetic data for the reaction at [Cr (phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 3.26, I = 0.30 M and T =
30.0 oC;
Time/s
0
20
40
60
80
At
0.0788
0.0929
0.1002
0.1068
0.1131
A8
0.1986
0.1986
0.1986
0.1986
0.1986
A8 - At
0.1198
0.1057
0.0984
0.0918
0.0855
ϭϯϭ
-ln(A8 - At)
2.12
2.25
2.32
2.39
2.46
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
100
120
140
160
180
200
220
240
260
280
0.1189
0.1235
0.1289
0.1335
0.1382
0.1421
0.1457
0.1494
0.1524
0.1551
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.0797
0.0751
0.0697
0.0651
0.0604
0.0565
0.0529
0.0492
0.0462
0.0435
2.53
2.59
2.66
2.73
2.81
2.87
2.94
3.01
3.07
3.13
Table 4.A.115. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 8.00 x 10-3 M, pH = 3.26, I = 0.30 M and T =
30.0 oC;
Time/s
At
A8
A8 - At
-ln(A8 - At)
0
0.1001
0.1983
0.0982
2.32
20
0.1122
0.1983
0.0861
2.45
40
0.1178
0.1983
0.0805
2.52
60
0.1249
0.1983
0.0734
2.61
80
0.1298
0.1983
0.0685
2.68
100
0.1351
0.1983
0.0632
2.76
120
0.1399
0.1983
0.0584
2.84
140
0.1435
0.1983
0.0548
2.90
160
0.1471
0.1983
0.0512
2.97
180
0.1512
0.1983
0.0471
3.06
200
0.1541
0.1983
0.0442
3.12
220
0.158
0.1983
0.0403
3.21
240
0.1602
0.1983
0.0381
3.27
260
0.1627
0.1983
0.0356
3.34
280
0.1651
0.1983
0.0332
3.41
III
Table 4.A.116. Kinetic data for the reaction at [Cr (phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 1.00 x 10-2 M, pH = 3.26, I = 0.30 M and T =
30.0 oC;
ϭϯϮ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Time/s
0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
At
0.1006
0.1111
0.1173
0.1238
0.1298
0.1341
0.1395
0.1432
0.1475
0.1511
0.1538
0.1572
0.1602
0.1629
0.1651
A8
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
A8 - At
0.0976
0.0871
0.0809
0.0744
0.0684
0.0641
0.0587
0.0550
0.0507
0.0471
0.0444
0.0410
0.038
0.0353
0.0331
-ln(A8 - At)
2.33
2.44
2.51
2.60
2.68
2.75
2.84
2.90
2.98
3.06
3.11
3.19
3.27
3.34
3.41
Table 4.A.117. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 2.00 x 10-2 M, pH = 3.26, I = 0.30 M and T =
30.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
180
200
220
At
0.1084
0.1206
0.1305
0.1351
0.1404
0.1439
0.1486
0.1524
0.1555
0.1586
0.1616
0.1642
A8
0.1981
0.1981
0.1981
0.1981
0.1981
0.1981
0.1981
0.1981
0.1981
0.1981
0.1981
0.1981
A8 - At
0.0897
0.0775
0.0676
0.0630
0.0577
0.0542
0.0495
0.0457
0.0426
0.0395
0.0365
0.0339
ϭϯϯ
-ln(A8 - At)
2.41
2.56
2.69
2.76
2.85
2.92
3.01
3.09
3.16
3.23
3.31
3.38
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
240
260
280
0.1672
0.1692
0.1712
0.1981
0.1981
0.1981
0.0309
0.0289
0.0269
3.48
3.54
3.62
Table 4.A.118. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 4.00 x 10-2 M, pH = 3.26, I = 0.30 M and T =
30.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
180
200
220
240
260
At
0.1161
0.1296
0.1358
0.1406
0.1446
0.1491
0.1522
0.1562
0.1594
0.1625
0.1648
0.1673
0.1697
0.1717
A8
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
A8 - At
0.0821
0.0686
0.0624
0.0576
0.0536
0.0491
0.0460
0.0420
0.0388
0.0357
0.0334
0.0309
0.0285
0.0265
-ln(A8 - At)
2.50
2.68
2.77
2.85
2.93
3.01
3.08
3.17
3.25
3.33
3.40
3.48
3.56
3.63
-ln(A∞ - At)
3.60
3.30
3.00
2.70
0
50
100
150
time/s
ϭϯϰ
200
250
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.33. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate ion at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 4.00 x
10-2 M, pH = 3.26, I = 0.30 M and T = 30.0 oC.
Table 4.A.119. Summary table for the variation of kobs with [IO4?], at
[CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, I = 0.30 M, pH = 3.26 and T =
30.0 oC;
102[IO4?],
M
0.20
0.40
0.80
1.00
2.00
4.00
1/[IO4?], M103kobs, s-1
2.98 ± 0.02
3.44 ± 0.02
3.68 ± 0.02
3.74 ± 0.02
3.87 ± 0.03
3.94 ± 0.03
1
500
250
125
100
50
25
1/kobs, s
335.6
290.7
271.7
267.4
258.4
253.8
4.A.4.2.3.5 Variation of [IO4?] at pH = 3.65
The kinetic data for the effect of IO4? on the rate of oxidation of [CrIII
(phen)2(H2O)2]3+ at T = 30 oC and pH = 3.65 are shown in Tables
4.A.120 – 4.A.125. A first order plot is represented in Fig. 4.34. The
dependence of kobs on [IO4?] is summarized in Table 4.A.126. Plotting
of 1/kobs vs 1/[IO4?], was found to be linear with an intercept I1 and a
slope S1 as shown in Fig. 4.37.
Table 4.A.120. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 2.00 x 10-3 M, pH = 3.65, I = 0.30 M and T =
30.0 oC;
ϭϯϱ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Time/s
At
A8
A8 - At
-ln(A8 - At)
0
0.0829
0.1984
0.1155
2.16
20
0.0931
0.1984
0.1053
2.25
40
0.1022
0.1984
0.0962
2.34
60
0.1108
0.1984
0.0876
2.43
80
0.1195
0.1984
0.0789
2.54
100
0.1271
0.1984
0.0713
2.64
120
0.1332
0.1984
0.0652
2.73
140
0.1393
0.1984
0.0591
2.83
160
0.1444
0.1984
0.054
2.92
180
0.1501
0.1984
0.0483
3.03
200
0.1541
0.1984
0.0443
3.12
220
0.1581
0.1984
0.0403
3.21
240
0.1612
0.1984
0.0372
3.29
260
0.1648
0.1984
0.0336
3.39
280
0.1678
0.1984
0.0306
3.49
300
0.1702
0.1984
0.0282
3.57
III
Table 4.A.121. Kinetic data for the reaction at [Cr (phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 3.65, I = 0.30 M and T =
30.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
180
200
220
240
At
0.0703
0.0804
0.0935
0.1046
0.1142
0.1244
0.1319
0.1389
0.1447
0.1501
0.1552
0.1597
0.1638
A8
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
A8 - At
0.1288
0.1187
0.1056
0.0945
0.0849
0.0747
0.0672
0.0602
0.0544
0.0490
0.0439
0.0394
0.0353
ϭϯϲ
-ln(A8 - At)
2.05
2.13
2.25
2.36
2.47
2.59
2.70
2.81
2.91
3.02
3.13
3.23
3.34
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
260
280
0.1668
0.1702
0.1991
0.1991
0.0323
0.0289
3.43
3.54
Table 4.A.122. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 8.00 x 10-3 , pH M= 3.65, I = 0.30 M and T =
30.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
180
200
220
240
260
At
0.0931
0.1113
0.1226
0.1313
0.1372
0.1455
0.1506
0.1559
0.1599
0.1642
0.1685
0.1715
0.1744
0.1769
A8
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
A8 - At
0.1055
0.0873
0.0760
0.0673
0.0614
0.0531
0.0480
0.0427
0.0387
0.0344
0.0301
0.0271
0.0242
0.0217
-ln(A8 - At)
2.25
2.44
2.58
2.70
2.79
2.94
3.04
3.15
3.25
3.37
3.50
3.61
3.72
3.83
Table 4.A.123. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 1.00 x 10-2 M, pH = 3.65, I = 0.30 M and T =
30.0 oC;
Time/s
0
20
40
60
80
100
120
140
At
0.0786
0.0914
0.1026
0.1143
0.1237
0.1321
0.1394
0.1454
A8
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
A8 - At
0.1198
0.1070
0.0958
0.0841
0.0747
0.0663
0.0590
0.0530
ϭϯϳ
-ln(A8 - At)
2.12
2.23
2.35
2.48
2.59
2.71
2.83
2.94
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
160
180
200
220
240
0.1513
0.1567
0.1609
0.1651
0.1688
0.1984
0.1984
0.1984
0.1984
0.1984
0.0471
0.0417
0.0375
0.0333
0.0296
3.06
3.18
3.28
3.40
3.52
Table 4.A.124. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 2.00 x 10-2 M, pH = 3.65, I = 0.30 M and T =
30.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
180
200
220
240
At
0.1019
0.1166
0.1269
0.1348
0.1419
0.1481
0.1541
0.1588
0.1632
0.1666
0.1698
0.1729
0.1754
A8
0.1967
0.1967
0.1967
0.1967
0.1967
0.1967
0.1967
0.1967
0.1967
0.1967
0.1967
0.1967
0.1967
A8 - At
0.0948
0.0801
0.0698
0.0619
0.0548
0.0486
0.0426
0.0379
0.0335
0.0301
0.0269
0.0238
0.0213
-ln(A8 - At)
2.36
2.52
2.66
2.78
2.90
3.02
3.16
3.27
3.40
3.50
3.62
3.74
3.85
Table 4.A.125. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 4.00 x 10-2 M, pH = 3.65, I = 0.30 M and T =
30.0 oC;
Time/s
0
At
0.0914
A8
0.1986
A8 - At
0.1072
ϭϯϴ
-ln(A8 - At)
2.23
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
20
40
60
80
100
120
140
160
180
200
220
240
0.1073
0.1202
0.1294
0.1362
0.1441
0.1504
0.1562
0.1609
0.1649
0.1687
0.1724
0.1749
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.1986
0.0913
0.0784
0.0692
0.0624
0.0545
0.0482
0.0424
0.0377
0.0337
0.0299
0.0262
0.0237
2.39
2.55
2.67
2.77
2.91
3.03
3.16
3.28
3.39
3.51
3.64
3.74
3.60
-ln(A∞ - At)
3.20
2.80
2.40
0
50
100
150
200
250
time/s
Fig. 4.34. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate ion at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 4.00 x
10-2 M, pH = 3.65, I = 0.30 M and T = 30.0 oC.
ϭϯϵ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.126. Summary table for the variation of kobs with [IO4?], at
[CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, I = 0.30 M, pH = 3.65 and T =
30.0 oC;
102[IO4?],
M
0.20
0.40
0.80
1.00
2.00
4.00
1/[IO4?], M103kobs, s-1
4.75 ±
0.02
5.42 ±
0.03
5.75 ±
0.05
5.83 ±
0.04
6.00 ±
0.03
6.10 ±
0.04
1
1/kobs, s
500
210.5
250
184.5
125
173.9
100
171.5
50
166.7
25
163.9
Table 4.A.127. Values of intercepts and slopes at 30.0 oC and various
pH values obtained from plots of kobs-1 versus [IO4?]-1;
pH
2.51
2.70
3.03
3.26
3.65
104[H+], M
30.90
20.41
9.33
5.50
2.30
102S1, M
88.00 ± 0.50
58.80 ± 0.78
29.30 ± 0.25
17.05 ± 0.25
9.70 ± 0.18
1500
A
1200
1/kobs, s
900
B
ϭϰϬ
600
C
D
300
E
10-2I1, s
9.93 ± 0.13
6.85 ± 0.19
3.63 ± 0.01
2.50 ± 0.01
1.61 ± 0.01
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.35. Plots of kobs-1 versus [IO4?]-1 at pH values, (A) 2.51, (B)
2.70, (C) 3.03 (D) 3.26 and (E) 3.65 at 30.0 oC.
10.0
6.0
-2
10 I1, s
8.0
4.0
2.0
0.0
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
+
10 [H ], M
3
Fig. 4.36. Dependence of I1 on [H+] at 30 oC.
1.00
0.80
S1, M
0.60
0.40
0.20
0.00
0.00
ϭϰϭ
0.50
1.00
1.50
3
2.00
+
10 [H ], M
2.50
3.00
3.50
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.37. Dependence of S1 on [H+] at 30 oC.
Table 4.A.128. Values of I2, S2 and I3 S3 at 30.0 oC obtained from plots
of I1 vs [H+] and S1 vs [H+], respectively;
10-2I2
0.92 ± 0.02
102I3
2.90 ± 0.56
10-5S2
2.9 ± 0.01
10-2S3
2.75 ± 0.03
4.A.4.2.4 Variation of [IO4?] at 40.0 oC
Under fixed reaction conditions, the effect of IO4? on the rate of
oxidation of [CrIII(phen)2(H2O)2]3+ was investigated. The pH was
varied from 2.51 – 4.39. Values of intercepts I1 and slope S1 at various
pH values are summarized in Table 4.A.159. Values of intercepts (I2
and I3) and slopes (S2 and S3) at various pH values obtained from plots
of I1 against [H+], Fig. 4.48 and S1 against [H+], Fig. 4.49, are shown in
Table 4.A.160.
4.A.4.2.4.1 Variation of [IO4?] at pH = 2.51
ϭϰϮ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
The kinetic data for the effect of IO4? on the rate of oxidation of [CrIII
(phen)2(H2O)2]3+ at T = 40 oC and pH = 2.51 are presented in Tables
4.A.129 – 4.A.133. A plot of first order is shown in Fig. 4.40. The
dependence of kobs on [IO4?] is summarized in Table 4.A.134. Plotting
of 1/kobs vs 1/[IO4?], was found to be linear with an intercept I1 and a
slope S1 as shown in Fig. 4.47.
Table 4.A.129. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 2.00 x 10-3 M, pH = 2.51, I = 0.30 M and T =
40.0 oC;
Time/s
At
A8
A8 - At
-ln(A8 - At)
0
0.0821
0.1987
0.1166
2.15
120
0.0995
0.1987
0.0992
2.31
240
0.1093
0.1987
0.0894
2.41
360
0.1185
0.1987
0.0802
2.52
480
0.1268
0.1987
0.0719
2.63
600
0.1347
0.1987
0.0640
2.75
720
0.14111
0.1987
0.0576
2.85
840
0.1472
0.1987
0.0515
2.97
960
0.1526
0.1987
0.0461
3.08
1080
0.1577
0.1987
0.0410
3.19
1200
0.1616
0.1987
0.0371
3.29
1320
0.1653
0.1987
0.0334
3.40
III
Table 4.A.130. Kinetic data for the reaction at [Cr (phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 2.51, I = 0.30 M and T =
40.0 oC;
Time/s
0
120
At
0.1011
0.0943
A8
0.1984
0.1984
A8 - At
0.0973
0.1041
ϭϰϯ
-ln(A8 - At)
2.33
2.26
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
240
360
480
600
720
840
960
1080
1200
0.1061
0.1171
0.1274
0.1361
0.1441
0.1509
0.1561
0.1613
0.1658
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.1984
0.0923
0.0813
0.0710
0.0623
0.0543
0.0475
0.0423
0.0371
0.0326
2.38
2.51
2.65
2.78
2.91
3.05
3.16
3.29
3.42
3.50
3.00
-ln(A∞ - At)
2.50
2.00
1.50
1.00
0.50
0.00
0.00
300.00
600.00
900.00
1200.00
time/s
Fig. 4.40. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate ion at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 4.00 x
10-3 M, pH = 2.51, I = 0.30 M and T = 40.0 oC.
ϭϰϰ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.131. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 8.00 x 10-3 M, pH = 2.51, I = 0.30 M and T =
40.0 oC;
Time/s
0
120
240
360
480
600
720
840
960
1080
1200
At
0.0728
0.0953
0.1081
0.1197
0.1311
0.1396
0.1469
0.1538
0.1598
0.1647
0.1686
A8
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
A8 - At
0.1254
0.1029
0.0901
0.0785
0.0671
0.0586
0.0513
0.0444
0.0384
0.0335
0.0296
-ln(A8 - At)
2.08
2.27
2.41
2.54
2.70
2.84
2.97
3.11
3.26
3.40
3.52
Table 4.A.132. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 1.00 x 10-2 M, pH = 2.51, I = 0.30 M and T =
40.0 oC;
Time/s
0
120
240
360
480
600
720
840
960
1080
1200
At
0.0737
0.0905
0.1063
0.1188
0.1292
0.1385
0.1465
0.1535
0.1591
0.1641
0.1683
A8
0.1981
0.1981
0.1981
0.1981
0.1981
0.1981
0.1981
0.1981
0.1981
0.1981
0.1981
A8 - At
0.1244
0.1076
0.0918
0.0793
0.0689
0.0596
0.0516
0.0446
0.0390
0.0340
0.0298
ϭϰϱ
-ln(A8 - At)
2.08
2.23
2.39
2.53
2.68
2.82
2.96
3.11
3.24
3.38
3.51
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.133. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 2.00 x 10-2 M, pH = 2.51, I = 0.30 M and T =
40.0 oC;
Time/s
0
120
240
360
480
600
720
840
960
1080
1200
At
0.0972
0.0881
0.1021
0.1161
0.1271
0.1371
0.1453
0.1528
0.1593
0.1647
0.1689
A8
0.1983
0.1983
0.1983
0.1983
0.1983
0.1983
0.1983
0.1983
0.1983
0.1983
0.1983
A8 - At
0.1011
0.1102
0.0962
0.0822
0.0712
0.0612
0.0530
0.0455
0.0390
0.0336
0.0294
-ln(A8 - At)
2.29
2.21
2.34
2.50
2.64
2.79
2.94
3.09
3.24
3.39
3.53
Table 4.A.134. Summary table for the variation of kobs with [IO4?], at
[CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, I = 0.30 M, pH = 2.51 and T =
40.0 oC;
102[IO4?],
M
0.20
0.40
0.80
1.00
103kobs, s-1
0.92 ± 0.01
1.08 ± 0.02
1.17 ± 0.02
1.19 ± 0.01
1/[IO4?],
M-1
500
250
125
100
ϭϰϲ
1/kobs, s
1087.0
925.9
854.7
840.3
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
2.00
1.24 ± 0.01
50
806.5
4.A.4.2.4.2 Variation of [IO4?] at pH = 2.70
The kinetic data for the effect of IO4? on the rate of oxidation of [CrIII
(phen)2(H2O)2]3+ at T = 40 oC and pH = 2.70 are presented in Tables
4.A.135 – 4.A.139 and the first order fitting represented as in Fig.
4.41. The dependence of kobs on [IO4?] is summarized in Table
4.A.140. Plotting of 1/kobs vs 1/[IO4?], was found to be linear with an
intercept I1 and a slope S1 as shown in Fig. 4.47.
Table 4.A.135. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 2.00 x 10-3 M, pH = 2.70, I = 0.30 M and T =
40.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
660
At
0.0810
0.0953
0.1057
0.1126
0.1183
0.1246
0.1312
0.1367
0.1419
0.1461
0.1501
0.1541
A8
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
A8 - At
0.1179
0.1036
0.0932
0.0863
0.0806
0.0743
0.0677
0.0622
0.0570
0.0528
0.0488
0.0448
ϭϰϳ
-ln(A8 - At)
2.14
2.27
2.37
2.45
2.52
2.60
2.69
2.78
2.86
2.94
3.02
3.11
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.136. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 2.70, I = 0.30 M and T =
40.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
660
At
0.0708
0.0805
0.0941
0.1034
0.1126
0.1201
0.1272
0.1337
0.1402
0.1452
0.1498
0.1545
A8
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
0.1988
A8 - At
0.1280
0.1183
0.1047
0.0954
0.0862
0.0787
0.0716
0.0651
0.0586
0.0536
0.0490
0.0443
-ln(A8 - At)
2.06
2.13
2.26
2.35
2.45
2.54
2.64
2.73
2.84
2.93
3.02
3.12
3.00
2.50
-ln(A∞ - At)
2.00
1.50
1.00
0.50
ϭϰϴ
0.00
0
100
200
300
400
time/s
500
600
700
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.41. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate ion at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 4.00 x
10-3 M, pH = 2.70, I = 0.30 M and T = 40.0 oC.
Table 4.A.137. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 8.00 x 10-3 M, pH = 2.70, I = 0.30 M and T =
40.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
At
0.0866
0.0983
0.1102
0.1191
0.1271
0.1342
0.1406
0.1461
0.1515
0.1560
0.1603
A8
0.1994
0.1994
0.1994
0.1994
0.1994
0.1994
0.1994
0.1994
0.1994
0.1994
0.1994
A8 - At
0.1128
0.1011
0.0892
0.0803
0.0723
0.0652
0.0588
0.0533
0.0479
0.0434
0.0391
-ln(A8 - At)
2.18
2.29
2.42
2.52
2.63
2.73
2.83
2.93
3.04
3.14
3.24
Table 4.A.138. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 1.00 x 10-2 M, pH = 2.70, I = 0.30 M and T =
40.0 oC;
Time/s
At
A8
A8 - At
ϭϰϵ
-ln(A8 - At)
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
0
60
120
180
240
300
360
420
480
540
600
0.0960
0.1109
0.1207
0.1289
0.1349
0.1412
0.1475
0.1523
0.1569
0.1613
0.1646
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1982
0.1022
0.0873
0.0775
0.0693
0.0633
0.0570
0.0507
0.0459
0.0413
0.0369
0.0336
2.28
2.44
2.56
2.67
2.76
2.86
2.98
3.08
3.19
3.30
3.39
Table 4.A.139. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 2.00 x 10-2 M, pH = 2.70, I = 0.30 M and T =
40.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
At
0.0863
0.1019
0.1133
0.1226
0.1304
0.1382
0.1443
0.1497
0.1545
0.1595
0.1632
A8
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
A8 - At
0.1128
0.0972
0.0858
0.0765
0.0687
0.0609
0.0548
0.0494
0.0446
0.0396
0.0359
ϭϱϬ
-ln(A8 - At)
2.18
2.33
2.46
2.57
2.68
2.80
2.90
3.01
3.11
3.23
3.33
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.140. Variation of kobs with [IO4?], at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, I = 0.30 M, pH = 2.70 and T = 40.0 oC;
102[IO4?],
M
0.20
0.40
0.80
1.00
2.00
103k2, M1 -1
s
1.38 ± 0.01
1.61 ± 0.02
1.74 ± 0.02
1.76 ± 0.01
1.84 ± 0.02
1/[IO4?],
M-1
500
250
125
100
50
10-2/kobs, s
7.25
6.21
5.75
5.68
5.43
4.A.4.2.4.3 Variation of [IO4?] at pH = 3.03
The kinetic data for the effect of IO4? on the rate of oxidation of [CrIII
(phen)2(H2O)2]3+ at pH = 3.03 are collected in Tables 4.A.141 –
4.A.145. Examples of first order fitting are shown in Figs. 4.41 – 4.43.
The dependence of kobs on [IO4?] is summarized in Table 4.A.146.
Plotting of 1/kobs vs 1/[IO4?], was found to be linear with an intercept I1
and a slope S1 as shown in Fig. 4.47.
Table 4.A.141. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 2.00 x 10-3 M, pH = 3.03, I = 0.30 M and T =
40.0 oC;
Time/s
0
40
80
120
At
0.0677
0.0921
0.1031
0.1133
A8
0.1996
0.1996
0.1996
0.1996
A8 - At
0.1319
0.1075
0.0965
0.0863
ϭϱϭ
ln(A8 - At)
2.03
2.23
2.34
2.45
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
160
200
240
280
320
360
400
440
480
520
0.1204
0.1286
0.1352
0.1427
0.1474
0.1527
0.1569
0.1612
0.1654
0.1687
0.1996
0.1996
0.1996
0.1996
0.1996
0.1996
0.1996
0.1996
0.1996
0.1996
0.0792
0.0710
0.0644
0.0569
0.0522
0.0469
0.0427
0.0384
0.0342
0.0309
2.54
2.65
2.74
2.87
2.95
3.06
3.15
3.26
3.38
3.48
Table 4.A.142. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 3.03, I = 0.30 M and T =
40.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
320
340
3.00
2.50
-ln(A∞ - At)
2.00
1.50
1.00
At
0.0675
0.0892
0.0977
0.1046
0.1106
0.1159
0.1202
0.1241
0.1282
0.1333
0.1365
0.1398
0.1431
0.1461
0.1492
0.1521
0.1552
0.1579
A8
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
0.1991
A8 - At
0.1316
0.1099
0.1014
0.0945
0.0885
0.0832
0.0789
0.0750
0.0709
0.0658
0.0626
0.0593
0.0560
0.0530
0.0499
0.0470
0.0439
0.0412
ϭϱϮ
-ln(A8 - At)
2.03
2.21
2.29
2.36
2.42
2.49
2.54
2.59
2.65
2.72
2.77
2.83
2.88
2.94
3.00
3.06
3.13
3.19
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.41. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate ion at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 4.00 x
10-3 M, pH = 3.03, I = 0.30 M and T = 40.0 oC.
Table 4.A.143. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 8.00 x 10-3 M, pH = 3.03, I = 0.30 M and T =
40.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
180
200
220
240
260
At
0.0802
0.0915
0.1001
0.1074
0.1123
0.1175
0.1231
0.1265
0.1321
0.1346
0.1388
0.1426
0.1462
0.1497
A8
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
A8 - At
0.1187
0.1074
0.0988
0.0915
0.0866
0.0814
0.0758
0.0724
0.0668
0.0643
0.0601
0.0563
0.0527
0.0492
ϭϱϯ
-ln(A8 - At)
2.13
2.23
2.31
2.39
2.45
2.51
2.58
2.63
2.71
2.74
2.81
2.88
2.94
3.01
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
280
300
320
340
0.1527
0.1554
0.1581
0.1610
0.1989
0.1989
0.1989
0.1989
0.0462
0.0435
0.0408
0.0379
3.07
3.13
3.20
3.27
Table 4.A.144. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 1.00 x 10-2 M, pH = 3.03, I = 0.30 M and T =
40.0 oC;
Time/s
0
20
40
60
80
100
120
At
0.0963
0.1167
0.1221
0.1262
0.1313
0.1346
0.1397
A8
0.1995
0.1995
0.1995
0.1995
0.1995
0.1995
0.1995
A8 - At
0.1032
0.0828
0.0774
0.0733
0.0682
0.0649
0.0598
ϭϱϰ
-ln(A8 - At)
2.27
2.49
2.56
2.61
2.69
2.73
2.82
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
140
160
180
200
220
240
260
280
300
320
0.1422
0.1455
0.1489
0.1524
0.1555
0.1587
0.1614
0.1636
0.1661
0.1680
0.1995
0.1995
0.1995
0.1995
0.1995
0.1995
0.1995
0.1995
0.1995
0.1995
0.0573
0.054
0.0506
0.0471
0.0440
0.0408
0.0381
0.0359
0.0334
0.0315
2.86
2.92
2.98
3.06
3.12
3.20
3.27
3.33
3.40
3.46
3.50
3.00
-ln(A∞ - At)
2.50
2.00
1.50
1.00
0.50
0.00
0
50
100
150
200
250
300
350
time/s
Fig. 4.42. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate ion at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 1.00 x
10-2 M, pH = 3.03, I = 0.30 M and T = 40.0 oC.
Table 4.A.145. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 2.00 x 10-2 M, pH = 3.03, I = 0.30 M and T =
40.0 oC;
Time/s
0
At
0.0719
A8
0.1987
A8 - At
0.1268
ϭϱϱ
-ln(A8 - At)
2.07
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
320
340
0.0864
0.0941
0.1018
0.1084
0.1145
0.1177
0.1231
0.1293
0.1338
0.1383
0.1418
0.1454
0.1487
0.1521
0.1548
0.1576
0.1603
0.1987
0.1987
0.1987
0.1987
0.1987
0.1987
0.1987
0.1987
0.1987
0.1987
0.1987
0.1987
0.1987
0.1987
0.1987
0.1987
0.1987
0.1123
0.1046
0.0969
0.0903
0.0842
0.0810
0.0756
0.0694
0.0649
0.0604
0.0569
0.0533
0.0500
0.0466
0.0439
0.0411
0.0384
2.19
2.26
2.33
2.40
2.47
2.51
2.58
2.67
2.73
2.81
2.87
2.93
3.00
3.07
3.13
3.19
3.26
3.00
2.50
-ln(A∞ - At)
2.00
1.50
1.00
0.50
0.00
0
50
100
150
200
250
300
350
time/s
Fig. 4.43. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate ion at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 2.00 x
10-2 M, pH = 3.03, I = 0.30 M and T = 40.0 oC.
ϭϱϲ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.146. Variation of kobs with [IO4?], at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, I = 0.30 M, pH = 3.03 and T = 40.0 oC;
102[IO4?],
M
0.20
0.40
0.80
1.00
2.00
103kobs, s-1
2.58 ± 0.02
2.96 ± 0.02
3.17 ± 0.03
3.23 ± 0.03
3.34 ± 0.02
1/[IO4?], M-1
500
250
125
100
50
10-2/kobs, s
3.88
3.38
3.15
3.10
2.99
4.A.4.2.4.4 Variation of [IO4?] at pH = 3.26
The kinetic data for the effect of IO4? on the rate of oxidation of [CrIII
(phen)2(H2O)2]3+ at T = 40 oC and pH = 3.26 are in Tables 4.A.147 –
4.A.151. The dependence of kobs on [IO4?] is summarized in Table
4.A.152. Plotting of 1/kobs vs 1/[IO4?], was found to be linear with I1
and S1 as shown in Fig. 4.47.
Table 4.A.147. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 2.00 x 10-3 M, pH = 3.26, I = 0.30 M and T =
40.0 oC;
Time/s
0
20
40
60
80
100
120
At
0.0718
0.0806
0.0901
0.0998
0.1063
0.1138
0.1205
A8
0.1990
0.1990
0.1990
0.1990
0.1990
0.1990
0.1990
A8 - At
0.1272
0.1184
0.1089
0.0992
0.0927
0.0852
0.0785
ϭϱϳ
-ln(A8 - At)
2.06
2.13
2.22
2.31
2.38
2.46
2.54
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
140
0.1249
0.1990
0.0741
2.60
160
0.1308
0.1990
0.0682
2.69
180
0.1355
0.1990
0.0635
2.76
200
0.1403
0.1990
0.0587
2.84
220
0.1447
0.1990
0.0543
2.91
240
0.1486
0.1990
0.0504
2.99
260
0.1523
0.1990
0.0467
3.06
280
0.1556
0.1990
0.0434
3.14
300
0.1587
0.1990
0.0403
3.21
III
Table 4.A.148. Kinetic data for the reaction at [Cr (phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 3.26, I = 0.30 M and T =
40.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
At
0.0873
0.0958
0.1054
0.1143
0.1222
0.1293
0.1349
0.1396
0.1444
0.1489
0.1535
0.1571
0.1607
0.1639
0.1667
0.1696
A8
0.1999
0.1999
0.1999
0.1999
0.1999
0.1999
0.1999
0.1999
0.1999
0.1999
0.1999
0.1999
0.1999
0.1999
0.1999
0.1999
A8 - At
0.1126
0.1041
0.0945
0.0856
0.0777
0.0706
0.0650
0.0603
0.0555
0.0510
0.0464
0.0428
0.0392
0.0360
0.0332
0.0303
-ln(A8 - At)
2.18
2.26
2.36
2.46
2.55
2.65
2.73
2.81
2.89
2.98
3.07
3.15
3.24
3.32
3.41
3.50
Table 4.A.149. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 8.00 x 10-3 M, pH = 3.26, I = 0.30 M and T =
40.0 oC;
ϭϱϴ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Time/s
At
A8
A8 - At
-ln(A8 - At)
0
0.0885
0.1985
0.1100
2.21
20
0.1070
0.1985
0.0915
2.39
40
0.1181
0.1985
0.0804
2.52
60
0.1252
0.1985
0.0733
2.61
80
0.1305
0.1985
0.0680
2.69
100
0.1359
0.1985
0.0626
2.77
120
0.1419
0.1985
0.0566
2.87
140
0.1466
0.1985
0.0519
2.96
160
0.1524
0.1985
0.0461
3.08
180
0.1555
0.1985
0.0430
3.15
200
0.1596
0.1985
0.0389
3.25
220
0.1629
0.1985
0.0356
3.34
240
0.1662
0.1985
0.0323
3.43
260
0.1691
0.1985
0.0294
3.53
III
Table 4.A.150. Kinetic data for the reaction at [Cr (phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 1.00 x 10-2 M, pH = 3.26, I = 0.30 M and T =
40.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
At
0.0718
0.0826
0.0951
0.1048
0.1143
0.1211
0.1285
0.1349
0.1398
0.1451
0.1502
0.1547
0.1588
0.1620
0.1656
A8
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
0.1989
A8 - At
0.1271
0.1163
0.1038
0.0941
0.0846
0.0778
0.0704
0.0640
0.0591
0.0538
0.0487
0.0442
0.0401
0.0369
0.0333
ϭϱϵ
-ln(A8 - At)
2.06
2.15
2.27
2.36
2.47
2.55
2.65
2.75
2.83
2.92
3.02
3.12
3.22
3.30
3.40
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
300
0.1686
0.1989
0.0303
3.50
Table 4.A.151. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 2.00 x 10-2 M, pH = 3.26, I = 0.30 M and T =
40.0 oC;
Time/s
At
A8
A8 - At
-ln(A8 - At)
0
0.0832
0.1991
0.1159
2.16
20
0.0980
0.1991
0.1011
2.29
40
0.1073
0.1991
0.0918
2.39
60
0.1173
0.1991
0.0818
2.50
80
0.1252
0.1991
0.0739
2.61
100
0.1313
0.1991
0.0678
2.69
120
0.1385
0.1991
0.0606
2.80
140
0.1424
0.1991
0.0567
2.87
160
0.1485
0.1991
0.0506
2.98
180
0.1531
0.1991
0.0460
3.08
200
0.1573
0.1991
0.0418
3.17
220
0.1614
0.1991
0.0377
3.28
240
0.1648
0.1991
0.0343
3.37
260
0.1681
0.1991
0.0310
3.47
280
0.1707
0.1991
0.0284
3.56
?
III
Table 4.A.152. Variation of kobs with [IO4 ], at [Cr (phen)2(H2O)23+] =
2.00 x 10-4 M, I = 0.30 M, pH = 3.26 and T = 40.0 oC;
102[IO4¯],
M
0.20
0.40
0.80
1.00
2.00
1/[IO4¯], M103kobs, s-1
3.81 ± 0.02
4.34 ± 0.03
4.64 ± 0.04
4.73 ± 0.03
4.87 ± 0.03
1
500
250
125
100
50
4.A.4.2.4.5 Variation of [IO4?] at pH = 4.39
ϭϲϬ
10-2/kobs, s
2.62
2.30
2.16
2.11
2.05
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
The kinetic data for the effect of IO4? on the rate of oxidation of [CrIII
(phen)2(H2O)2]3+ at pH = 4.39 are presented in Tables 4.A.153 –
4.A.157. Examples of first order fitting are shown in Figs. 4.44 – 4.46.
The dependence of kobs on [IO4?] is summarized in Table 4.A.158.
Plotting of 1/kobs vs 1/[IO4?], was found to be linear with an intercept I1
and a slope S1 as shown in Fig. 4.47.
Table 4.A.153. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 2.00 x 10-3 M, pH = 4.39, I = 0.30 M and T =
40.0 oC;
Time/s
At
A8
A8 - At
-ln(A8 - At)
0
0.1130
0.2024
0.0894
2.41
10
0.1354
0.2024
0.0670
2.70
20
0.1432
0.2024
0.0592
2.83
30
0.1497
0.2024
0.0527
2.94
40
0.1542
0.2024
0.0482
3.03
50
0.1587
0.2024
0.0437
3.13
60
0.1632
0.2024
0.0392
3.24
70
0.1674
0.2024
0.0350
3.35
80
0.1709
0.2024
0.0315
3.46
90
0.1732
0.2024
0.0292
3.53
100
0.1761
0.2024
0.0263
3.64
110
0.1786
0.2024
0.0238
3.74
120
0.1811
0.2024
0.0213
3.85
130
0.1831
0.2024
0.0193
3.95
140
0.1847
0.2024
0.0177
4.03
150
0.1865
0.2024
0.0159
4.14
III
Table 4.A.154. Kinetic data for the reaction at [Cr (phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 4.39, I = 0.30 M and T =
40.0 oC;
Time/s
At
A8
A8 - At
ϭϲϭ
-ln(A8 - At)
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
0.1147
0.1309
0.1394
0.1471
0.1532
0.1593
0.1641
0.1691
0.1726
0.1771
0.1802
0.1834
0.1859
0.1885
0.1908
0.1927
0.2098
0.2098
0.2098
0.2098
0.2098
0.2098
0.2098
0.2098
0.2098
0.2098
0.2098
0.2098
0.2098
0.2098
0.2098
0.2098
0.0951
0.0789
0.0704
0.0627
0.0566
0.0505
0.0457
0.0407
0.0372
0.0327
0.0296
0.0264
0.0239
0.0213
0.0190
0.0171
2.35
2.54
2.65
2.77
2.87
2.99
3.09
3.20
3.29
3.42
3.52
3.63
3.73
3.85
3.96
4.07
4.00
-ln(A∞ - At)
3.00
2.00
1.00
0.00
0
20
40
60
80
100
120
140
160
180
time/s
Fig. 4.44. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate ion at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 4.00 x
10-3 M, pH = 4.39, I = 0.30 M and T = 40.0 oC.
ϭϲϮ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.155. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 8.00 x 10-3 M, pH = 4.39, I = 0.30 M and T =
40.0 oC;
Time/s
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
At
0.1283
0.1527
0.1581
0.1644
0.1694
0.1729
0.1774
0.1808
0.1837
0.1863
0.1884
0.1908
0.1926
0.1945
0.1961
0.1974
0.1988
0.1998
A8
0.2091
0.2091
0.2091
0.2091
0.2091
0.2091
0.2091
0.2091
0.2091
0.2091
0.2091
0.2091
0.2091
0.2091
0.2091
0.2091
0.2091
0.2091
A8 - At
0.0808
0.0564
0.0510
0.0447
0.0397
0.0362
0.0317
0.0283
0.0254
0.0228
0.0207
0.0183
0.0165
0.0146
0.013
0.0117
0.0103
0.0093
4
-ln(A∞ - At)
3
2
1
0
0
20
40
60
80
100
time/s
120
140
ϭϲϯ
160
180
ln(A8 - At)
2.52
2.88
2.98
3.11
3.23
3.32
3.45
3.56
3.67
3.78
3.88
4.00
4.10
4.23
4.34
4.45
4.58
4.68
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.45. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate ion at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 8.00 x
10-3 M, pH = 4.39, I = 0.30 M and T = 40.0 oC.
Table 4.A.156. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 1.00 x 10-2 M, pH = 4.39, I = 0.30 M and T =
40.0 oC;
Time/s
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
At
0.1272
0.1519
0.1576
0.1646
0.1687
0.1741
0.1781
0.1817
0.1851
0.1879
0.1907
0.1929
0.1952
0.1969
0.1985
0.2001
0.2017
A8
0.2126
0.2126
0.2126
0.2126
0.2126
0.2126
0.2126
0.2126
0.2126
0.2126
0.2126
0.2126
0.2126
0.2126
0.2126
0.2126
0.2127
A8 - At
0.0854
0.0607
0.0550
0.0480
0.0439
0.0385
0.0345
0.0309
0.0275
0.0247
0.0219
0.0197
0.0174
0.0157
0.0141
0.0125
0.0110
ϭϲϰ
=ln(A8 - At)
2.46
2.80
2.90
3.04
3.13
3.26
3.37
3.48
3.59
3.70
3.82
3.93
4.05
4.15
4.26
4.38
4.51
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.157. Kinetic data for the reaction at [CrIII(phen)2(H2O)23+] =
2.00 x10-4 M, [IO4?] = 2.00 x 10-2 M, pH = 4.39, I = 0.30 M and T =
40.0 oC;
Time/s
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
At
0.1303
0.1544
0.1629
0.1699
0.1762
0.1812
0.1855
0.1893
0.1932
0.1967
0.1991
0.2025
0.2047
0.2068
0.2087
0.2103
0.2117
0.2130
A8
0.2239
0.2239
0.2239
0.2239
0.2239
0.2239
0.2239
0.2239
0.2239
0.2239
0.2239
0.2239
0.2239
0.2239
0.2239
0.2239
0.2239
0.2239
A8 - At
0.0936
0.0695
0.0610
0.0540
0.0477
0.0427
0.0384
0.0346
0.0307
0.0272
0.0248
0.0214
0.0192
0.0171
0.0152
0.0136
0.0122
0.0109
ϭϲϱ
-ln(A8 - At)
2.37
2.67
2.80
2.92
3.04
3.15
3.26
3.36
3.48
3.60
3.70
3.84
3.95
4.07
4.19
4.30
4.41
4.52
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
4.00
-ln(A∞ - At)
3.00
2.00
1.00
0.00
0
20
40
60
80
100
120
140
160
180
time/s
Fig. 4.46. A first order fitting of oxidation of [CrIII(phen)2(H2O)2]3+ by
periodate ion at [CrIII(phen)2(H2O)23+] = 2.00 x 10-4 M, [IO4?] = 2.00 x
10-2 M, pH = 4.39, I = 0.30 M and T = 40.0 oC.
Table 4.A.158. Variation of kobs with [IO4?], at [CrIII(phen)2(H2O)23+] =
2.00 x 10-4 M, I = 0.30 M, pH = 4.39 and T = 40.0 oC;
102[IO4¯],
M
0.20
0.40
0.80
1.00
2.00
103kobs, s-1
10.09 ±
0.05
10.83 ±
0.06
11.25 ±
0.05
11.34 ±
0.05
11.52 ±
0.05
1/[IO4¯],
M-1
1/kobs, s
500
99.11
250
92.34
125
88.89
100
88.18
50
86.81
ϭϲϲ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.A.159. Values of intercepts and slopes at 40.0 oC and various
pH values obtained from plots of kobs-1 versus [IO4?]-1;
pH
104[H+],
M
2.51
30.90
2.70
19.90
3.03
9.33
3.26
5.50
102S1, M
61.80 ±
0.85
39.78 ±
0.83
19.46 ±
0.22
12.67 ±
0.24
4.39
0.41
2.73 ± 0.10
10-2I1, s
7.75 ± 0.02
5.25 ± 0.02
2.89 ± 0.01
1.99 ± 0.01
0.850 ±
0.002
1200
A
900
1/kobs, s
B
600
C
300
D
E
0
0
100
200
300
−
400
500
-1
1/[IO4 ], M
Fig. 4.47. Plots of kobs-1 versus [IO4?]-1 at pH values, (A) 2.51, (B)
2.70, (C) 3.03 (D) 3.26 and (E) 4.39 at 40.0 oC.
ϭϲϳ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
8.0
7.0
6.0
4.0
-2
10 I1, s
5.0
3.0
2.0
1.0
0.0
0.0
5.0
10.0
15.0
4
20.0
25.0
30.0
35.0
+
10 [H ], M
Fig. 4.48. Dependence of I1 on [H+] at 40 oC.
7.0
6.0
5.0
10S1, M
4.0
3.0
2.0
1.0
0.0
0.0
5.0
10.0
15.0
20.0
4
25.0
30.0
35.0
+
10 [H ], M
Fig. 4.49. Dependence of S1 on [H+] at 40 oC.
Table 4.A.160. Values of I2, S2 and I3 S3 at 40oC obtained from plots of
I1 vs [H+] and S1 vs [H+], respectively;
10-2I2
0.76 ± 0.01
ϭϲϴ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
102I3
1.77 ± 0.30
10-5S2
2.26 ± 0.06
10-2S3
1.93 ± 0.15
Table 4.A.161. Calculated values of K3, K5, K6 and ket at different
temperatures;
T, oC
20.0
25.0
30.0
40.0
104 K3, M 102K5, M-1
1.25 ±
9.86 ±
0.20
0.20
1.21 ±
10.23 ±
0.17
0.20
1.05 ±
10.60 ±
0.20
0.30
0.92 ±
11.72 ±
0.13
0.10
103K6, M-1
103ket, s-1
2.20 ± 0.35
8.40 ± 0.91
2.83 ± 0.40
9.80 ± 0.43
3.17 ± 0.60
10.87 ±
0.19
4.31 ± 0.67
13.12 ±
0.20
4.A.4.3 Thermodynamic parameters
The enthalpies of formation of the pre-equilibrium processes ? H5 and
? H6, are calculated from plots of lnK5 vs 1/T and lnK6 vs 1/T, Figs,
4.50 and 4.51, respectively. The values of ? H5 and ? H6 are calculated
from the slopes these plots as 6.62 ± 0.51 and 24.68 ± 2.17 kJ mol-1
respectively. The entropies ? S5 and ? S6 associated with these
processes are obtained from the intercepts as 79.2 ± 1.7 J K-1 mol-1 and
148.5 ± 7.2 J K-1 mol-1 respectively. The enthalpy and entropy of
-2.12
-2.16
ln K5
-2.20
-2.24
ϭϲϵ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
activation, ? H? and ? S? , are determined using the Eyring equation,
Fig. 4.52, as 14.2 ± 1.2 kJ mol-1 and -236.0 ± 24.4 J K-1 mol-1
respectively.
Fig. 4.50. Plot of ln K5 vs 1/T.
8.4
ln K6
8.2
8.0
7.8
7.6
3.15
3.23
3.30
3
3.38
-1
10 /T, K
ϭϳϬ
3.45
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.51. Plot of ln K6 vs 1/T.
-10.10
et
ln(k /T)
-10.20
-10.30
-10.40
-10.50
3.23
3.30
3.38
3.45
3
-1
10 /T, K
Fig. 4.52. Plot of Erying equation (ln ket/T) vs 1/T).
4. B. [CrIIIcdta(H2O)]? complex
4. B.1 Characterization of the complex
4. B.1.1 UV – vis absorption spectrum
The [CrIIIcdta(H2O)]? complex displayed two absorption peaks at 545
nm and 393 nm, in aqueous solutions and in phosphate buffer (pH =
6.44). These peak positions are in fairly good agreement with the
ϭϳϭ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
literature values which are 540 nm and 395 nm [77]. It was found that
phosphate buffer does not affect these positions, as shown in Fig. 4.53.
Fig. 4.53. (A) Absorption spectrum of [CrIIIcdta(H2O)]? complex in
aqueous solution. (B) Absorption spectrum of [CrIIIcdta(H2O)]?
complex in phosphate buffer at pH = 6.44.
4.B.1.2 The molar extinction coefficient
The molar extinction coefficient of the complex was determined
spectrophotometrically. It was determined as 238 M-1 cm-1, which is in
good agreement with literature value (245 M-1 cm-1) [77].
Table 3.B.1. Absorbance of Cr(III), at I = 0.30 M, pH = 6.25 and T =
25oC;
103[CrIII(cdta)H2O]¯,
M
Absorbance
ϭϳϮ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
0.50
0.1182
1.00
0.2432
2.00
0.4736
3.00
0.6981
4.00
0.9628
5.00
1.1819
4.B.2 Stoichiometry of the reaction
The stoichiometry of the [CrIIIcdta(H2O)]? : IO4? reactions is
determined using excess of Cr(III) complex concentration over that of
periodate as shown in Table 4.B.2. The Cr(III) : IO4? ratio is 2.00 : 3.02
± 0.08.
Table 4.B.2. Stoichiometric data for oxidation of [CrIIIcdta(H2O)]? by
[IO4?] at pH = 6.34;
104[CrIII]total,
104[IO4¯],
105[CrVI]produced,
M
M
Abs
M
stoichiometry
6.00
6.00
1.3413
38.32
1.57
5.00
1.1498
32.85
1.52
4.00
0.9341
26.69
1.50
3.00
0.7102
20.29
1.48
2.00
0.4498
12.85
1.56
1.00
0.2391
6.83
1.46
1.51 ± 0.04
ϭϳϯ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
The stoichiometry for the reaction may thus be described by eq. (4.4).
This is in agreement with the fact that at low [H+], IO4? is a two
electron oxidant. Since IO3? is a weak oxidant in weakly acidic and
neutral aqueous solutions; mixturers containing [CrIIIcdta(H2O)]? and
excess IO3? showed no formation of chromium(VI) when left for
several hours.
2[CrIII(cdta)H2O]? + 3I(VII)?
2Cr(VI) + 3IO3? + cdta
(4.4)
Fig. 4.54. Absorption spectra of the reaction mixture at different time
intervals, at [CrIII(cdta)(H2O)¯] = 2.0 x 10-4 M, [IO4?] = 1.0 x 10-2 M,
pH = 6.32, I = 0.30 M and T = 25.0 oC.
4.B.3 Oxidation product
The UV-visible absorption spectrum of the oxidation product of
[CrIIIcdta(H2O)]? by IO4? was recorded on Schimadzu UV-1800
ϭϳϰ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
spectrophotometer as a function of time over the 360 - 370 nm range.
The violet color of complex solution changed gradually to yellow and
its original absorption maxima, at 393 and 545 nm, were replaced by a
single peak at 360 - 370 nm at the pH range used due to
chromium(VI), Fig. 4.54. This is an indication of formation of
chromium(VI). To confirm presence of chromium(VI), a small amount
of sym-diphenylcarbazide was added to the chromium(VI) in acidic
medium solution, the yellow color changed to pink immediately [76].
4.B.4 Results of kinetic measurements
4.B.4.1 Effect of variation of complex concentration on the rate of
the reaction
The rate of oxidation of [CrIIIcdta(H2O)]? by IO4? was studied at
constant IO4? concentration of 0.01 M, ionic strength = 0.30 M, T =
25.0 oC and pH = 6.08. The complex concentration was varied over the
range (0.50 – 4.00) x 10-4 M. The results are collected in Tables 4.B.3 4.B.7. Fig. 4.55 represents the second order fitting for some of these
data. The results in Table 4.B.8 show that k2 is unaffected when the
concentration of chromium(III) complex was varied at a constant
reaction conditions. This is indicative of second order dependence on
ϭϳϱ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
complex concentration. The rate law of the reaction is described by eq.
(4.5);
Rate = kobs [CrIIIcdta(H2O)?]2
(4.5)
Table 4.B.3. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 5.00 x
10-5 M, [IO4?] = 0.01 M, pH = 6.08, I = 0.30 M and T = 25.0 oC;
Time/s
0
40
80
120
160
200
240
280
320
360
400
440
480
At
0.0523
0.0696
0.0817
0.0902
0.0977
0.1036
0.1092
0.1142
0.1178
0.1216
0.1248
0.1278
0.1311
A8
0.1799
0.1799
0.1799
0.1799
0.1799
0.1799
0.1799
0.1799
0.1799
0.1799
0.1799
0.1799
0.1799
(A8 - At)
0.1276
0.1103
0.0982
0.0897
0.0822
0.0763
0.0707
0.0657
0.0621
0.0583
0.0551
0.0521
0.0488
1/(A8 - At)
7.84
9.07
10.18
11.15
12.17
13.11
14.14
15.22
16.10
17.15
18.15
19.19
20.49
Table 4.B.4. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 1.00 x
10-4 M, [IO4?] = 0.01 M, pH = 6.08, I = 0.30 M and T = 25.0 oC;
Time/s
0
20
40
60
80
100
120
At
0.0769
0.1072
0.1328
0.1535
0.1714
0.1871
0.2004
A8
0.3560
0.3560
0.3560
0.3560
0.3560
0.3560
0.3560
(A8 - At)
0.2791
0.2488
0.2232
0.2025
0.1846
0.1689
0.1556
ϭϳϲ
1/(A8 - At)
3.58
4.02
4.48
4.94
5.42
5.92
6.43
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
140
160
180
200
220
240
260
280
0.2114
0.2209
0.2297
0.2373
0.2431
0.2486
0.2543
0.2592
0.3560
0.3560
0.3560
0.3560
0.3560
0.3560
0.3560
0.3560
0.1446
0.1351
0.1263
0.1187
0.1129
0.1074
0.1017
0.0968
6.92
7.40
7.92
8.42
8.86
9.31
9.83
10.33
10.00
8.00
1/(A∞ - At)
6.00
4.00
2.00
0.00
0
50
100
150
200
250
time/s
Fig. 4.55. A second order fitting of oxidation of [CrIIIcdta(H2O)]? by
periodate ion at [CrIIIcdta(H2O)?] = 1.00 x 10-4 M, [IO4?] = 0.01 M, pH
= 6.08, I = 0.30 M and T = 25.0 oC.
Table 4.B.5. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 0.01 M, pH = 6.08, I = 0.30 M and T = 25.0 oC;
Time/s
0
10
20
At
0.4076
0.4849
0.5142
A8
0.8054
0.8054
0.8054
(A8 - At)
0.3978
0.3205
0.2912
ϭϳϳ
1/(A8 - At)
2.51
3.12
3.43
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
0.5312
0.5524
0.5647
0.5746
0.5917
0.6019
0.6119
0.6208
0.6279
0.6361
0.6433
0.6489
0.6551
0.6603
0.6657
0.8054
0.8054
0.8054
0.8054
0.8054
0.8054
0.8054
0.8054
0.8054
0.8054
0.8054
0.8054
0.8054
0.8054
0.8054
0.2742
0.2530
0.2407
0.2308
0.2137
0.2035
0.1935
0.1846
0.1775
0.1693
0.1621
0.1565
0.1503
0.1451
0.1397
3.65
3.95
4.15
4.33
4.68
4.91
5.17
5.42
5.63
5.91
6.17
6.39
6.65
6.89
7.16
Table 4.B.6. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 3.00 x
10-4 M, [IO4?] = 0.01 M, pH = 6.08, I = 0.30 M and T = 25.0 oC;
Time/s
At
A8
(A8 - At)
1/(A8 - At)
0
0.4421
1.131
0.6889
1.45
10
0.5576
1.131
0.5734
1.74
20
0.6293
1.131
0.5017
1.99
30
0.6886
1.131
0.4424
2.26
40
0.7336
1.131
0.3974
2.52
50
0.7710
1.131
0.3600
2.78
60
0.8019
1.131
0.3291
3.04
70
0.8265
1.131
0.3045
3.28
80
0.8465
1.131
0.2845
3.51
90
0.8647
1.131
0.2663
3.76
100
0.8813
1.131
0.2497
4.00
110
0.8943
1.131
0.2367
4.22
120
0.9063
1.131
0.2247
4.45
130
0.9167
1.131
0.2143
4.67
140
0.9277
1.131
0.2033
4.92
III
Table 4.B.7. Kinetic data for the reaction at [Cr cdta(H2O)?] = 4.00 x
10-4 M, [IO4?] = 0.01 M, pH = 6.08, I = 0.30 M and T = 25.0 oC;
ϭϳϴ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Time/s
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
At
0.6518
0.8067
0.8979
0.9673
1.0170
1.0531
1.0893
1.1138
1.1382
1.157
1.1738
1.1879
1.2005
1.2137
1.2259
1.2368
1.2458
A8
1.436
1.436
1.436
1.436
1.436
1.436
1.436
1.436
1.436
1.436
1.436
1.436
1.436
1.436
1.436
1.436
1.436
(A8 - At)
0.7842
0.6293
0.5381
0.4687
0.4190
0.3829
0.3467
0.3222
0.2978
0.2790
0.2622
0.2481
0.2355
0.2223
0.2101
0.1992
0.1902
1/(A8 - At)
1.28
1.59
1.86
2.13
2.39
2.61
2.88
3.10
3.36
3.58
3.81
4.03
4.25
4.50
4.76
5.02
5.26
Table 4.B.8. Summary table for the variation of k2 with
[CrIIIcdta(H2O)]? at [IO4?] = 0.01 M, I = 0.30 M, pH = 6.08 and T =
25.0 oC;
104[Cr(III)]T, M
102k2, M-1s-1
0.50
2.51 ± 0.01
1.00
2.44 ± 0.01
2.00
2.49 ± 0.01
3.00
2.43 ± 0.02
4.00
2.41 ± 0.01
ϭϳϵ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
4.B.4.2 Effect of IO4? concentration
The dependence of k2 on [IO4?] was investigated over the range (0.30 3.00) x 10- 2 M at fixed [Cr(III)], pH, ionic strength and temperature.
Results are collected in Tables 4.B.9 – 4.B.14. The results in Table
4.B.15 show that the second order rate constant, varies linearly with
[IO4?] as shown in Fig. 4.56. The rate law for the oxidation of the
complex at fixed reaction conditions is given by eq. (4.6).
d[Cr(VI)]/dt = k3[CrIIIcdta (H2O)-]2[IO4?]
(4.6)
Table 4.B.9. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 3.00 x 10-3 M, pH = 6.35, I = 0.30 M and T = 25.0 oC;
Time/s
0
10
20
30
40
50
60
70
80
90
100
110
120
At
0.2154
0.2521
0.2888
0.3154
0.3421
0.3619
0.3809
0.3992
0.4158
0.4288
0.4406
0.4523
0.4621
A8
0.6918
0.6918
0.6918
0.6918
0.6918
0.6918
0.6918
0.6918
0.6918
0.6918
0.6918
0.6918
0.6918
A8 - At
0.4764
0.4397
0.4030
0.3764
0.3497
0.3299
0.3109
0.2926
0.2760
0.2630
0.2512
0.2395
0.2297
ϭϴϬ
1/(A8 - At)
2.10
2.27
2.48
2.66
2.86
3.03
3.22
3.42
3.62
3.80
3.98
4.18
4.35
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
130
140
150
160
0.4721
0.4801
0.4879
0.4942
0.6918
0.6918
0.6918
0.6918
0.2197
0.2117
0.2039
0.1976
4.55
4.72
4.90
5.06
Table 4.B.10. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 5.00 x 10-3 M, pH = 6.35, I = 0.30 M and T = 25.0 oC;
Time/s
0
10
20
30
40
50
60
70
80
90
100
110
120
130
At
0.2088
0.2406
0.2843
0.3232
0.3491
0.3732
0.3974
0.4149
0.4325
0.4500
0.4632
0.4757
0.4868
0.4960
A8
0.6687
0.6687
0.6687
0.6687
0.6687
0.6687
0.6687
0.6687
0.6687
0.6687
0.6687
0.6687
0.6687
0.6687
A8 - At
0.4599
0.4281
0.3844
0.3455
0.3196
0.2955
0.2713
0.2538
0.2362
0.2187
0.2055
0.1930
0.1819
0.1727
1/(A8 - At)
2.17
2.34
2.60
2.89
3.13
3.38
3.69
3.94
4.23
4.57
4.87
5.18
5.50
5.79
Table 4.B.11. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 9.00 x 10-3 M, pH = 6.35, I = 0.30 M and T = 25.0 oC;
Time/s
0
At
0.3466
A8
0.7751
A8 - At
0.4285
ϭϴϭ
1/(A8 - At)
2.33
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
20
40
60
80
100
120
140
160
180
200
220
240
0.4762
0.5459
0.5910
0.6214
0.6438
0.6620
0.6741
0.6840
0.6918
0.6988
0.7044
0.7099
0.7751
0.7751
0.7751
0.7751
0.7751
0.7751
0.7751
0.7751
0.7751
0.7751
0.7751
0.7751
0.2989
0.2292
0.1841
0.1537
0.1313
0.1131
0.1010
0.0911
0.0833
0.0763
0.0707
0.0652
3.35
4.36
5.43
6.51
7.62
8.84
9.90
10.98
12.00
13.11
14.14
15.34
Table 4.B.12. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 1.50 x 10-2 M, pH = 6.35, I = 0.30 M and T = 25.0 oC;
Time/s
0
10
20
30
40
50
60
70
80
90
100
110
120
130
At
0.3601
0.4407
0.4948
0.5231
0.5507
0.5676
0.5819
0.5928
0.6017
0.6092
0.6162
0.6218
0.6271
0.6312
A8
0.7031
0.7031
0.7031
0.7031
0.7031
0.7031
0.7031
0.7031
0.7031
0.7031
0.7031
0.7031
0.7031
0.7031
A8 - At
0.3430
0.2624
0.2083
0.1800
0.1524
0.1355
0.1212
0.1103
0.1014
0.0939
0.0869
0.0813
0.0760
0.0719
ϭϴϮ
1/(A8 - At)
2.92
3.81
4.80
5.56
6.56
7.38
8.25
9.07
9.86
10.65
11.51
12.30
13.16
13.91
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.B.13. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 2.00 x 10-2 M, pH = 6.35, I = 0.30 M and T = 25.0 oC;
Time/s
0
10
20
30
40
50
60
70
80
90
100
110
At
0.3287
0.3817
0.4691
0.5099
0.5410
0.5605
0.5762
0.5880
0.5967
0.6065
0.6135
0.6194
A8
0.6849
0.6849
0.6849
0.6849
0.6849
0.6849
0.6849
0.6849
0.6849
0.6849
0.6849
0.6849
A8 - At
0.3562
0.3032
0.2158
0.1750
0.1439
0.1244
0.1087
0.0969
0.0882
0.0784
0.0714
0.0655
1/(A8 - At)
2.81
3.30
4.63
5.71
6.95
8.04
9.20
10.32
11.34
12.76
14.01
15.27
Table 4.B.14. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 3.00 x 10-2 M, pH = 6.35, I = 0.30 M and T = 25.0 oC;
Time/s
0
10
20
30
40
50
60
70
80
At
0.3874
0.4441
0.5171
0.5569
0.5841
0.6021
0.6165
0.6272
0.6349
A8
0.6975
0.6975
0.6975
0.6975
0.6975
0.6975
0.6975
0.6975
0.6975
A8 - At
0.3101
0.2534
0.1804
0.1406
0.1134
0.0954
0.0810
0.0703
0.0626
ϭϴϯ
1/(A8 - At)
3.22
3.95
5.54
7.11
8.82
10.48
12.35
14.22
15.97
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
90
100
0.6412
0.6460
0.6975
0.6975
0.0563
0.0515
17.76
19.42
Table 4.B.15. Summary table for the variation of k2 with [IO4?] at
[CrIIIcdta(H2O)-] = 2.00 x 10-4 M, I = 0.30 M, pH = 6.35 and T = 25.0
o
C;
102[IO4?],
M
0.30
0.50
0.90
1.50
2.00
3.00
102k2, M-1s-1
1.87 ± 0.01
2.88 ± 0.04
5.46 ± 0.02
8.37 ± 0.06
11.77 ± 0.10
17.40 ± 0.10
k3, M-2s-1
6.23
5.76
6.07
5.58
5.89
5.80
Average = 5.89 ±
0.02
16.0
-1
10 k2, M s
-1
12.0
ϭϴϰ
2
8.0
4.0
0.0
0.00
0.50
1.00
1.50
2.00
2.50
3.00
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.56. Variation of kobs with [IO4?] at [CrIIIcdta(H2O)?] = 2.00 x 10-4
M, I = 0.30 M and T = 25.0 oC.
4.B.4.3 Effect of hydrogen ion concentration on the oxidation rate
The effect of [H+] on the reaction rate was investigated over the pH
range 5.52 – 7.44 under constant reaction conditions. The kinetic data
for the effect of pH on the second order rate constants, k2, are given in
Tables 4.B.16 – 4.B.27. Example of a second order fitting is shown in
Fig. 4.57. Results are summarized in Table 3.B.28. The dependence of
k3 on [H+] was found to fit a polynomial of the second degree, as
shown in Fig. 4.58 (r2 = 0.999). The dependence of k3 on [H+] is thus
described by eq. (4.7).
1/k3 = a + b[H+] + c[H+]2
(4.7)
ϭϴϱ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.B.16. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 5.52, I = 0.30 M and T = 25.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
660
At
0.1999
0.3044
0.3235
0.3374
0.3486
0.3607
0.3701
0.3795
0.3872
0.3955
0.4027
0.4095
A8
0.5998
0.5998
0.5998
0.5998
0.5998
0.5998
0.5998
0.5998
0.5998
0.5998
0.5998
0.5998
A8 - At
0.3999
0.2954
0.2763
0.2624
0.2512
0.2391
0.2297
0.2203
0.2126
0.2043
0.1971
0.1903
1/(A8 - At)
2.50
3.39
3.62
3.81
3.98
4.18
4.35
4.54
4.70
4.89
5.07
5.25
5.00
1/(A∞ - At)
4.00
3.00
2.00
1.00
0.00
0
100
200
300
400
time/s
ϭϴϲ
500
600
700
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.57. A second order fitting of oxidation of [CrIIIcdta(H2O)]? by
periodate ion at [CrIIIcdta(H2O)?] = 2.00 x 10-4 M, [IO4?] = 4 x 10-3 M,
pH = 5.52, I = 0.30 M and T = 25.0 oC.
Table 4.B.17. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 5.67, I = 0.30 M and T = 25.0 oC;
Time/s
0
40
80
120
160
200
240
280
320
360
400
440
480
At
0.2009
0.2998
0.3211
0.3388
0.3529
0.3657
0.3783
0.3871
0.3969
0.4057
0.4138
0.4211
0.4275
A8
0.5994
0.5994
0.5994
0.5994
0.5994
0.5994
0.5994
0.5994
0.5994
0.5994
0.5994
0.5994
0.5994
A8 - At
0.3985
0.2996
0.2783
0.2606
0.2465
0.2337
0.2211
0.2123
0.2025
0.1937
0.1856
0.1783
0.1719
1/(A8 - At)
2.51
3.34
3.59
3.84
4.06
4.28
4.52
4.71
4.94
5.16
5.39
5.61
5.82
Table 4.B.18. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 5.75, I = 0.30 M and T = 25.0 oC;
Time/s
0
40
80
At
0.1724
0.2721
0.2986
A8
0.5934
0.5934
0.5934
A8 - At
0.4210
0.3213
0.2948
ϭϴϳ
1/(A8 - At)
2.38
3.11
3.39
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
120
160
200
240
280
320
360
400
440
480
520
560
0.3220
0.3433
0.3614
0.3778
0.3897
0.4001
0.4095
0.4187
0.4264
0.4342
0.4411
0.4467
0.5934
0.5934
0.5934
0.5934
0.5934
0.5934
0.5934
0.5934
0.5934
0.5934
0.5934
0.5934
0.2714
0.2501
0.2320
0.2156
0.2037
0.1933
0.1839
0.1747
0.1670
0.1592
0.1523
0.1467
3.68
4.00
4.31
4.64
4.91
5.17
5.44
5.72
5.99
6.28
6.57
6.82
Table 4.B.19. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 5.98, I = 0.30 M and T = 25.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
At
0.1314
0.2360
0.2724
0.3004
0.3212
0.3399
0.3565
0.3725
0.3851
0.3959
0.4058
0.4159
0.4243
0.4320
0.4391
0.4458
A8
0.5991
0.5991
0.5991
0.5991
0.5991
0.5991
0.5991
0.5991
0.5991
0.5991
0.5991
0.5991
0.5991
0.5991
0.5991
0.5991
A8 - At
0.4677
0.3631
0.3267
0.2987
0.2779
0.2592
0.2426
0.2266
0.2140
0.2032
0.1933
0.1832
0.1748
0.1671
0.1600
0.1533
ϭϴϴ
1/(A8 - At)
2.14
2.75
3.06
3.35
3.60
3.86
4.12
4.41
4.67
4.92
5.17
5.46
5.72
5.98
6.25
6.52
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.B.20. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 6.16, I = 0.30 M and T = 25.0 oC;
Time/s
At
A8
A8 - At
1/(A8 - At)
0
0.1051
0.6223
0.5172
1.93
20
0.1669
0.6223
0.4554
2.20
40
0.2236
0.6223
0.3987
2.51
60
0.2811
0.6223
0.3412
2.93
80
0.3202
0.6223
0.3021
3.31
100
0.3526
0.6223
0.2697
3.71
120
0.3791
0.6223
0.2432
4.11
140
0.4011
0.6223
0.2212
4.52
160
0.4207
0.6223
0.2016
4.96
180
0.4359
0.6223
0.1864
5.36
200
0.4498
0.6223
0.1725
5.80
220
0.4613
0.6223
0.1610
6.21
240
0.4707
0.6223
0.1516
6.60
260
0.4790
0.6223
0.1433
6.98
III
Table 4.B.21. Kinetic data for the reaction at [Cr cdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 6.24, I = 0.30 M and T = 25.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
180
200
At
0.1273
0.2123
0.2802
0.3311
0.3735
0.4002
0.4312
0.4494
0.4669
0.4811
0.4931
A8
0.654
0.654
0.654
0.654
0.654
0.654
0.654
0.654
0.654
0.654
0.654
A8 - At
0.5267
0.4417
0.3738
0.3229
0.2805
0.2538
0.2228
0.2046
0.1871
0.1729
0.1609
ϭϴϵ
1/(A8 - At)
1.90
2.26
2.68
3.10
3.57
3.94
4.49
4.89
5.34
5.78
6.22
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.B.22. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 6.45, I = 0.30 M and T = 25.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
180
200
At
0.2392
0.3284
0.3821
0.4215
0.4507
0.4733
0.4912
0.5072
0.5198
0.5307
0.5389
A8
0.6633
0.6633
0.6633
0.6633
0.6633
0.6633
0.6633
0.6633
0.6633
0.6633
0.6633
A8 - At
0.4241
0.3349
0.2812
0.2418
0.2126
0.1900
0.1721
0.1561
0.1435
0.1326
0.1244
1/(A8 - At)
2.36
2.99
3.56
4.14
4.70
5.26
5.81
6.41
6.97
7.54
8.04
Table 4.B.23. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 6.63, I = 0.30 M and T = 25.0 oC;
Time/s
0
10
20
30
40
50
60
70
At
0.1402
0.2528
0.3004
0.3401
0.3711
0.4003
0.4235
0.4378
A8
0.6682
0.6682
0.6682
0.6682
0.6682
0.6682
0.6682
0.6682
A8 - At
0.5280
0.4154
0.3678
0.3281
0.2971
0.2679
0.2447
0.2304
ϭϵϬ
1/(A8 - At)
1.89
2.41
2.72
3.05
3.37
3.73
4.09
4.34
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
80
90
100
110
120
0.4532
0.4666
0.4793
0.4909
0.5016
0.6682
0.6682
0.6682
0.6682
0.6682
0.2150
0.2016
0.1889
0.1773
0.1666
4.65
4.96
5.29
5.64
6.00
Table 4.B.24. Kinetic data for the reaction at [CrIIIcdta(H2O)]] = 2.00 x
10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 6.85, I = 0.30 M and T = 25.0 oC;
Time/s
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
At
0.1199
0.1851
0.2682
0.3274
0.3718
0.4102
0.4406
0.4648
0.4829
0.5012
0.5149
0.5284
0.5398
0.5504
0.5589
A8
0.7102
0.7102
0.7102
0.7102
0.7102
0.7102
0.7102
0.7102
0.7102
0.7102
0.7102
0.7102
0.7102
0.7102
0.7102
A8 - At
0.5903
0.5251
0.4420
0.3828
0.3384
0.3000
0.2696
0.2454
0.2273
0.2090
0.1953
0.1818
0.1704
0.1598
0.1513
1/(A8 - At)
1.69
1.90
2.26
2.61
2.96
3.33
3.71
4.07
4.40
4.78
5.12
5.50
5.87
6.26
6.61
Table 4.B.25. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 7.02, I = 0.30 M and T = 25.0 oC;
Time/s
0
20
40
At
0.0706
0.1511
0.205
A8
0.7582
0.7582
0.7582
A8 - At
0.6876
0.6071
0.5532
ϭϵϭ
1/(A8 - At)
1.45
1.65*
1.81
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
60
80
100
120
140
160
180
200
220
240
260
0.3616
0.4535
0.5111
0.5532
0.5805
0.6033
0.6205
0.6337
0.6457
0.6549
0.6624
0.7582
0.7582
0.7582
0.7582
0.7582
0.7582
0.7582
0.7582
0.7582
0.7582
0.7582
0.3966
0.3047
0.2471
0.2050
0.1777
0.1549
0.1381
0.1245
0.1125
0.1031
0.0959
2.52
3.28
4.05
4.88
5.63
6.46
7.24
8.03
8.89
9.70
10.43
Table 4.B.26. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 7.18, I = 0.30 M and T = 25.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
180
200
220
240
260
At
0.1525
0.2787
0.4088
0.4953
0.5493
0.5876
0.6139
0.6359
0.6500
0.6631
0.6741
0.6829
0.6899
0.6963
A8
0.7809
0.7809
0.7809
0.7809
0.7809
0.7809
0.7809
0.7809
0.7809
0.7809
0.7809
0.7809
0.7809
0.7809
A8 - At
0.6284
0.5022
0.3721
0.2856
0.2316
0.1933
0.1670
0.1450
0.1309
0.1178
0.1068
0.0980
0.0910
0.0846
ϭϵϮ
1/(A8 - At)
1.59
1.99
2.69
3.50
4.32
5.17
5.99
6.90
7.64
8.49
9.36
10.20
10.99
11.82
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.B.27. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 7.44, I = 0.30 M and T = 25.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
180
200
220
240
At
0.1523
0.2727
0.4188
0.5063
0.5603
0.5956
0.6219
0.6419
0.6576
0.6699
0.6801
0.6887
0.6956
A8
0.7832
0.7832
0.7832
0.7832
0.7832
0.7832
0.7832
0.7832
0.7832
0.7832
0.7832
0.7832
0.7832
A8 - At
0.6309
0.5105
0.3644
0.2769
0.2229
0.1876
0.1613
0.1413
0.1256
0.1133
0.1031
0.0945
0.0876
1/(A8 - At)
1.59
1.96
2.74
3.61
4.49
5.33
6.20
7.08
7.96
8.83
9.70
10.58
11.42
Table 4.B.28. Summary table for the variation of kobs with pH at
[CrIIIcdta(H2O)?]= 2.00 x 10-4 M, [IO4?] = 4.00 x 10-3 M, I = 0.30 M
and T = 25.0 oC;
107[H+],
k3, M-2s-
pH
M
102k2, M-1s-1
1
102/k3, M2s
5.52
30.20
3.06 ± 0.01
0.765
130.72
5.67
21.40
5.59 ± 0.01
1.398
71.56
5.75
17.80
7.15 ± 0.01
1.788
55.94
5.98
10.50
13.30 ± 0.01
3.325
30.08
6.16
6.92
20.30 ± 0.01
5.075
19.70
6.24
5.75
22.10 ± 0.01
5.525
18.10
ϭϵϯ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
6.45
3.55
28.20 ± 0.01
7.060
14.16
6.63
2.34
32.40 ± 0.03
8.100
12.35
6.85
1.41
36.20 ± 0.02
9.050
11.05
7.02
0.96
39.60 ± 0.03
9.900
10.10
7.18
0.66
41.40 ± 0.02
10.350
9.66
7.44
0.36
43.30 ± 0.02
10.825
9.24
1.50
1.20
2
1/k3, M s
0.90
0.60
0.30
0.00
0.0
5.0
10.0
15.0
7
20.0
25.0
30.0
35.0
+
10 [H ], M
Fig. 4.58. Polynomial fit of the second degree of 1/k3 versus [H+] at
25.0 oC.
4.B.4.4 Iodate effect
Tables 4.B.29 – 4.B.30, show that when IO3? was added to the reaction
mixture, the rate of oxidation did not change. k2 was determined in the
presence and absence of IO3? as (1.39 ± 0.01) x 10-2 M-1s-1 and (1.35 ±
0.01) x 10-2 M-1s-1, respectively.
Table 4.B.29. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 0.01 M, pH = 6.01, I = 0.30 M and T = 25.0 oC;
ϭϵϰ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Time/s
0
60
120
180
240
300
360
420
480
540
600
660
At
0.1545
0.2844
0.3705
0.4285
0.4665
0.4952
0.5125
0.5292
0.5431
0.5545
0.5637
0.5713
A8
0.6643
0.6643
0.6643
0.6643
0.6643
0.6643
0.6643
0.6643
0.6643
0.6643
0.6643
0.6643
A8 - At
0.5098
0.3799
0.2938
0.2358
0.1978
0.1691
0.1518
0.1351
0.1212
0.1098
0.1006
0.0930
1/(A8 - At)
1.96
2.63
3.40
4.24
5.06
5.91
6.59
7.40
8.25
9.11
9.94
10.75
12.00
10.00
1/(A∞ - At)
8.00
6.00
4.00
2.00
0.00
0
100
200
300
400
500
600
700
time/s
Fig. 4.59. A second order fitting of oxidation of [CrIIIcdta(H2O)]? by
periodate ion at [CrIIIcdta(H2O)?] = 2.00 x 10-4 M, [IO4?] = 0.01 M, pH
= 6.01, I = 0.30 M and T = 25.0 oC.
ϭϵϱ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.B.30. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 0.01 M, [IO3?] = 2.00 x 10-4 M, pH = 6.01, I = 0.30 M
and T = 25.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
660
At
0.1995
0.3569
0.4312
0.4719
0.5027
0.5222
0.5387
0.5526
0.5630
0.5722
0.5807
0.5873
A8
0.6733
0.6733
0.6733
0.6733
0.6733
0.6733
0.6733
0.6733
0.6733
0.6733
0.6733
0.6733
A8 - At
0.4738
0.3164
0.2421
0.2014
0.1706
0.1511
0.1346
0.1207
0.1103
0.1011
0.0926
0.0860
1/(A8 - At)
2.11
3.16
4.13
4.97
5.86
6.62
7.43
8.29
9.07
9.89
10.80
11.63
12.00
10.00
1/(A∞ - At)
8.00
6.00
4.00
2.00
0.00
0
100
200
300
400
time/s
ϭϵϲ
500
600
700
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.60. A second order fitting of oxidation of [CrIIIcdta(H2O)]? by
periodate ion at [CrIIIcdta(H2O)?] = 2.00 x 10-4 M, [IO4?] = 0.01 M,
[IO3?] = 2.00 x 10-4 M, pH = 6.01, I = 0.30 M and T = 25.0 oC.
4.B.4.5 Effect of temperature on the rate of the reaction
The dependence of k2 on temperature was investigated over the range
20.0 – 45.0 oC at fixed [Cr(III)], [IO4?], pH and ionic strength. Results
are collected in Tables 4.B.31 – 4.B.35. Table 4.B.36 shows the
calculation for Erying equation. Plot of ln(k2/T) vs 1/T is shown in
Fig. 4.61. The value of ? H* was determined as 28.8 ± 0.1 kJ mol-1.
The entropy of activation was calculated as -147.9 ± 6.1 J mol-1 K-1.
Table 4.B.31. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 0.01 M, pH = 6.15, I = 0.30 M and T = 20.0 oC;
Time/s
0
60
120
180
240
At
0.0702
0.1125
0.2361
0.3277
0.3931
A8
0.7191
0.7191
0.7191
0.7191
0.7191
A8 - At
0.6489
0.6066
0.4830
0.3914
0.3260
ϭϵϳ
1/(A8 - At)
1.54
1.65
2.07
2.55
3.07
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
300
360
420
480
540
600
660
720
780
0.4398
0.4756
0.5056
0.5262
0.5439
0.5581
0.5705
0.5812
0.5898
0.7191
0.7191
0.7191
0.7191
0.7191
0.7191
0.7191
0.7191
0.7191
0.2793
0.2435
0.2135
0.1929
0.1752
0.1610
0.1486
0.1379
0.1293
3.58
4.11
4.68
5.18
5.71
6.21
6.73
7.25
7.73
Table 4.B.32. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 0.01 M, pH = 6.15, I = 0.30 M and T = 25.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
At
0.1914
0.3437
0.4193
0.4693
0.5072
0.5319
0.5536
0.5716
0.5851
0.5973
0.6066
A8
0.7249
0.7249
0.7249
0.7249
0.7249
0.7249
0.7249
0.7249
0.7249
0.7249
0.7249
A8 - At
0.5335
0.3812
0.3056
0.2556
0.2177
0.1930
0.1713
0.1533
0.1398
0.1276
0.1183
1/(A8 - At)
1.87
2.62
3.27
3.91
4.59
5.18
5.84
6.52
7.15
7.84
8.45
Table 4.B.33. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 0.01 M, pH = 6.15, I = 0.30 M and T = 35.0 oC;
ϭϵϴ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Time/s
0
60
120
180
240
300
360
420
480
540
600
At
0.0608
0.1044
0.3479
0.4574
0.5233
0.5667
0.5941
0.6162
0.6325
0.6456
0.6551
A8
0.7508
0.7508
0.7508
0.7508
0.7508
0.7508
0.7508
0.7508
0.7508
0.7508
0.7508
A8 - At
0.6900
0.6464
0.4029
0.2934
0.2275
0.1841
0.1567
0.1346
0.1183
0.1052
0.0957
1/(A8 - At)
1.45
1.55
2.48
3.41
4.40
5.43
6.38
7.43
8.45
9.51
10.45
Table 4.B.34. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 0.01 M, pH = 6.15, I = 0.30 M and T = 40.0 oC;
Time/s
0
80
160
240
320
400
480
560
640
720
800
At
0.0818
0.1555
0.3886
0.4898
0.5399
0.5732
0.5955
0.6111
0.6223
0.6317
0.6387
A8
0.7014
0.7014
0.7014
0.7014
0.7014
0.7014
0.7014
0.7014
0.7014
0.7014
0.7014
A8 - At
0.6196
0.5459
0.3128
0.2116
0.1615
0.1282
0.1059
0.0903
0.0791
0.0697
0.0627
ϭϵϵ
1/(A8 - At)
1.61
1.83
3.20
4.73
6.19
7.80
9.44
11.07
12.64
14.35
15.95
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.B.35. Kinetic data for the reaction at [CrIIIcdta(H2O)?] = 2.00 x
10-4 M, [IO4?] = 0.01 M, pH = 6.15, I = 0.30 M and T = 45.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
At
0.1601
0.2572
0.4314
0.5157
0.5611
0.5921
0.6114
0.6255
0.6368
0.6458
A8
0.7206
0.7206
0.7206
0.7206
0.7206
0.7206
0.7206
0.7206
0.7206
0.7206
A8 - At
0.5605
0.4634
0.2892
0.2049
0.1595
0.1285
0.1092
0.0951
0.0838
0.0748
1/(A8 - At)
1.78
2.16
3.46
4.88
6.27
7.78
9.16
10.52
11.93
13.37
Table 4.B.36. Variation of k2 with temperature;
T,
K
293
298
308
313
318
103/T, K1
3.41
3.36
3.25
3.20
3.15
k3, M-1s-1
0.86
1.08
1.66
1.97
2.35
104(k2/T)
29.35
36.24
53.90
62.94
73.90
ln(k2/T)
-5.83
-5.62
-5.22
-5.07
-4.91
-9.50
ln(k2/T)
-9.75
-10.00
-10.25
ϮϬϬ
-10.50
3.10
3.20
3.30
3
-1
10 /T, K
3.40
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.61. Plot of Erying equation
4. C [CrIIIdtpa(H2O)]2- complex
4.C.1 Characterization of the complex
The [CrIIIdtpa(H2O)]2- complex displayed two absorption peaks at 552
nm and 387 nm, in aqueous solutions and in phosphate buffer (pH =
6.56). These peak positions are in fairly good agreement with the
literature values which are 558 nm and 385 nm [78]. It was found that
phosphate buffer does not affect these positions, as shown in Fig. 4.62.
ϮϬϭ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.62. (A) Absorption spectrum of [CrIIIdtpa(H2O)]2- complex in
aqueous solution. (B) Absorption spectrum of [CrIIIdtpa(H2O)]2complex in phosphate buffer at pH = 6.56.
4.C.2 Stoichiometry of the reaction
The stoichiometry of the [CrIIIdtpa(H2O)]2- : IO4? reactions was
determined using excess of Cr(III) complex concentration over that of
periodate as shown in Table 3.C.1. The Cr(III) : IO4? ratio is
determined as 2.00 : 3.06 ± 0.18. The stoichiometry for the reaction
may thus be described by eq. (4.8). This is in agreement with the fact
that at low [H+], IO4? is a two electron oxidant. Since IO3? is a weak
oxidant in weakly acidic and neutral aqueous solutions; mixtures
containing [CrIIIdtpa(H2O)]2- and excess IO3? showed no formation of
chromium(VI) when left for several hours.
2[CrIIIdtpa(H2O)]2- + 3IO4? ?
2Cr(VI) + 3IO3? + dtpa
(4.8)
Table 4.C.1 Stoichiometric data for oxidation of [CrIIIdtpa(H2O)]2- by
[IO4?] at pH = 5.56;
103[CrIII],
104[IO4?],
M
M
104[CrVI]produced,
Stoichiometr
M
y
Abs
ϮϬϮ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
1.597
1.00
10.00
0
5.91
1.69
3.27
1.53
1.79
1.40
1.30
1.54
0.82
1.52
0.66
1.51
0.882
5.00
0
0.482
2.50
3
0.350
2.00
7
0.222
1.25
3
0.178
1.00
7
1.53 ± 0.09
4.C.3 Results of kinetic measurements
With periodate concentration in large excess over that of the complex,
the kinetics showed marked deviation from first order dependence on
[Cr(III)]. However, plots of 1/(A8 -At) vs time are linear up to = 90% of
reaction.
ϮϬϯ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
4.C.3.1 Effect of variation of complex concentration on the rate of
the reaction
The rate of oxidation of [CrIIIdtpa(H2O)]2- by IO4? was studied at
constant IO4? concentration of 0.01 M, ionic strength = 0.30 M, T =
25.0 oC and pH = 6.36. The complex concentration was varied over the
range (0.50 – 5.00) x 10-4 M. The results are collected in Tables 4.C.2
– 4.C.7. Fig. 4.63 represents the second order fitting for some of these
data. The results in Table 4.C.8 show that k2 is unaffected when the
concentration of chromium(III) complex was varied at a constant
reaction conditions. This is indicative of a second order dependence on
complex concentration. The rate law of the reaction is described by eq.
(4.9);
Rate = k2 [CrIIIdtpa(H2O)Ϯ-]2
(4.9)
Table 4.C.2. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 5.00 x
10-5 M, [IO4?] = 0.01 M, pH = 6.36, I = 0.30 M and T = 25.0 oC;
Time/s
0
40
80
120
160
200
240
At
0.0502
0.0672
0.0717
0.0756
0.0783
0.0814
0.0838
A8
0.1431
0.1431
0.1431
0.1431
0.1431
0.1431
0.1431
ϮϬϰ
A8 - At
0.0929
0.0759
0.0714
0.0675
0.0648
0.0617
0.0593
1/(A8 - At)
10.76
13.18
14.01
14.81
15.43
16.21
16.86
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
280
0.0858
0.1431
0.0573
17.45
320
0.0881
0.1431
0.0550
18.18
360
0.0901
0.1431
0.0530
18.87
400
0.0922
0.1431
0.0509
19.65
440
0.0940
0.1431
0.0491
20.37
480
0.0955
0.1431
0.0476
21.01
520
0.0971
0.1431
0.0460
21.74
560
0.0986
0.1431
0.0445
22.47
600
0.1001
0.1431
0.0430
23.26
III
Table 4.C.3. Kinetic data for the reaction at [Cr dtpa(H2O)2-] = 1.00 x
10-4 M, [IO4?] = 0.01 M, pH = 6.36, I = 0.30 M and T = 25.0 oC;
Time/s
0
20
40
80
120
160
200
240
280
320
360
400
440
480
520
At
0.1679
0.1910
0.2272
0.2286
0.2306
0.2317
0.2333
0.2348
0.2360
0.2371
0.2382
0.2392
0.2405
0.2414
0.2422
A8
0.2779
0.2779
0.2779
0.2779
0.2779
0.2779
0.2779
0.2779
0.2779
0.2779
0.2779
0.2779
0.2779
0.2779
0.2779
A8 - At
0.1100
0.0869
0.0507
0.0493
0.0473
0.0462
0.0446
0.0431
0.0419
0.0408
0.0397
0.0387
0.0374
0.0365
0.0357
1/(A8 - At)
9.09
11.51
19.72
20.28
21.14
21.65
22.42
23.20
23.87
24.51
25.19
25.84
26.74
27.40
28.01
400
600
25.00
1/(A∞ - At)
20.00
15.00
ϮϬϱ
10.00
5.00
0.00
0
100
200
300
500
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.63. A second order fitting of oxidation of [CrIIIdtpa(H2O)]2- by
periodate ion at [CrIIIdtpa(H2O)2-] = 1.00 x 10-4 M, [IO4?] = 0.01 M, pH
= 6.36, I = 0.30 M and T = 25.0 oC.
Table 4.C.4. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 2.00 x
10-4 M, [IO4?] = 0.01 M, pH = 6.36, I = 0.30 M and T = 25.0 oC;
Time/s
0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
320
340
360
At
0.2705
0.3932
0.3994
0.4082
0.4133
0.4187
0.4231
0.4299
0.4347
0.4386
0.4426
0.4459
0.4494
0.4519
0.4546
0.4575
0.4598
0.4622
0.4645
A8
0.5436
0.5436
0.5436
0.5436
0.5436
0.5436
0.5436
0.5436
0.5436
0.5436
0.5436
0.5436
0.5436
0.5436
0.5436
0.5436
0.5436
0.5436
0.5436
A8 - At
0.2731
0.1504
0.1442
0.1354
0.1303
0.1249
0.1205
0.1137
0.1089
0.1050
0.1010
0.0977
0.0942
0.0917
0.0890
0.0861
0.0838
0.0814
0.0791
ϮϬϲ
1/(A8 - At)
3.66
6.65
6.93
7.39
7.67
8.01
8.30
8.80
9.18
9.52
9.90
10.24
10.62
10.91
11.24
11.61
11.93
12.29
12.64
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.C.5. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 3.00 x
10-4 M, [IO4?] = 0.01 M, pH = 6.36, I = 0.30 M and T = 25.0 oC;
Time/s
At
A8
A8 - At
1/(A8 - At)
0
0.3968
0.8299
0.4331
2.31
20
0.5534
0.8299
0.2765
3.62
40
0.5828
0.8299
0.2471
4.05
60
0.6061
0.8299
0.2238
4.47
80
0.6232
0.8299
0.2067
4.84
100
0.6364
0.8299
0.1935
5.17
120
0.6485
0.8299
0.1814
5.51
140
0.6588
0.8299
0.1711
5.84
160
0.6692
0.8299
0.1607
6.22
180
0.6786
0.8299
0.1513
6.61
200
0.6854
0.8299
0.1445
6.92
220
0.6923
0.8299
0.1376
7.27
240
0.6982
0.8299
0.1317
7.59
260
0.7044
0.8299
0.1255
7.97
III
Table 4.C.6. Kinetic data for the reaction at [Cr dtpa(H2O)2-] = 4.00 x
10-4 M, [IO4?] = 0.01 M, pH = 6.36, I = 0.30 M and T = 25.0 oC;
Time/s
0
40
80
120
160
200
240
280
320
360
400
440
480
520
560
600
640
At
0.4049
0.6692
0.7429
0.7821
0.8170
0.8414
0.8584
0.8725
0.8842
0.8946
0.9041
0.9106
0.9168
0.9227
0.9275
0.9321
0.9362
A8
1.0102
1.0102
1.0102
1.0102
1.0102
1.0102
1.0102
1.0102
1.0102
1.0102
1.0102
1.0102
1.0102
1.0102
1.0102
1.0102
1.0102
A8 - At
0.6053
0.3410
0.2673
0.2281
0.1932
0.1688
0.1518
0.1377
0.1260
0.1156
0.1061
0.0996
0.0934
0.0875
0.0827
0.0781
0.0740
ϮϬϳ
1/(A8 - At)
1.65
2.93
3.74
4.38
5.18
5.92
6.59
7.26
7.94
8.65
9.43
10.04
10.71
11.43
12.09
12.80
13.51
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.C.7. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 5.00 x
10-4 M, [IO4?] = 0.01 M, pH = 6.36, I = 0.30 M and T = 25.0 oC;
Time/s
At
A8
A8 - At
1/(A8 - At)
0
0.3007
1.2201
0.9194
1.09
40
0.4101
1.2201
0.8100
1.23
80
0.6701
1.2201
0.5500
1.82
120
0.8236
1.2201
0.3965
2.52
160
0.9107
1.2201
0.3094
3.23
200
0.9659
1.2201
0.2542
3.93
240
1.0026
1.2201
0.2175
4.60
280
1.0293
1.2201
0.1908
5.24
320
1.0509
1.2201
0.1692
5.91
360
1.0695
1.2201
0.1506
6.64
400
1.0834
1.2201
0.1367
7.32
440
1.0961
1.2201
0.1240
8.06
480
1.1052
1.2201
0.1149
8.70
520
1.1137
1.2201
0.1064
9.40
560
1.1212
1.2201
0.0989
10.11
600
1.1274
1.2201
0.0927
10.79
Table 4.C.8. Summary table for the variation of kobs with
[CrIIIdtpa(H2O)]2- at [IO4?] = 0.01 M, pH = 6.36, I = 0.30 M and T =
25.0 oC;
104[Cr(III)]T, M
0.50
1.00
2.00
3.00
4.00
5.00
102k2, M-1s-1
1.77 ± 0.01
1.75 ± 0.01
1.77 ± 0.01
1.77 ± 0.01
1.75 ± 0.01
1.72 ± 0.01
4.C.3.2 Effect of IO4? concentration
The dependence of k2 on [IO4?] was investigated over the range (0.50 6.0) x 10- 2 M at fixed [Cr(III)], pH, ionic strength and temperature.
ϮϬϴ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Results are collected in Tables 4.C.9 – 4.C.14. Fig. 4.64 represents the
second order fitting for some of these data. The results in Table 4.C.15
show that the second order rate constant varies linearly with [IO4?] as
shown in Fig.3.65. The rate law for the oxidation of the complexe at
fixed reaction conditions is given by eq. (4.10);
d[Cr(VI)]/dt = k3[CrIIIL(H2O)2-]2[IO4?]
(4.10)
Table 4.C.9 Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 3.00 x
10-4 M, [IO4?] = 5.00 x 10-3 M, pH = 6.26, I = 0.30 M and T = 25.0 oC;
Time/s
At
A8
A8 - At
1/(A8 - At)
0
0.2822
0.7817
0.4995
2.00
80
0.5437
0.7817
0.2380
4.20
160
0.5769
0.7817
0.2048
4.88
240
0.6006
0.7817
0.1811
5.52
320
0.6175
0.7817
0.1642
6.09
400
0.6341
0.7817
0.1476
6.78
480
0.6462
0.7817
0.1355
7.38
560
0.6559
0.7817
0.1258
7.95
640
0.6652
0.7817
0.1165
8.58
720
0.6729
0.7817
0.1088
9.19
800
0.6799
0.7817
0.1018
9.82
Table 4.C.10. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 3.00
x 10-4 M, [IO4?] = 7.00 x 10-3 M, pH = 6.26, I = 0.30 M and T = 25.0
o
C;
Time/s
0
40
80
120
At
0.3608
0.5363
0.5686
0.5908
A8
0.7865
0.7865
0.7865
0.7865
A8 - At
0.4257
0.2502
0.2179
0.1957
ϮϬϵ
1/(A8 - At)
2.35
4.00
4.59
5.11
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
160
200
240
280
320
360
400
440
480
520
560
600
0.6071
0.6211
0.6321
0.6425
0.6515
0.6595
0.6667
0.6731
0.6778
0.6828
0.6878
0.6918
0.7865
0.7865
0.7865
0.7865
0.7865
0.7865
0.7865
0.7865
0.7865
0.7865
0.7865
0.7865
0.1794
0.1654
0.1544
0.1440
0.1350
0.1270
0.1198
0.1134
0.1087
0.1037
0.0987
0.0947
5.57
6.05
6.48
6.94
7.41
7.87
8.35
8.82
9.20
9.64
10.13
10.56
10.00
1/(A∞ - At)
8.00
6.00
4.00
2.00
0.00
0
100
200
300
400
500
600
time/s
Fig. 4.64. A second order fitting of oxidation of [CrIIIdtpa(H2O)]2- by
periodate ion at [CrIIIdtpa(H2O)2-] = 3.00 x 10-4 M, [IO4?] = 7.00 x 10-3
M, pH = 6.26, I = 0.30 M and T = 25.0 oC.
ϮϭϬ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.C.11. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 3.00
x 10-4 M, [IO4?] = 1.00 x 10-2 M, pH = 6.26, I = 0.30 M and T = 25.0
o
C;
Time/s
0
40
80
120
160
200
240
280
320
360
400
440
480
520
560
600
At
0.3349
0.4983
0.5528
0.5821
0.6048
0.6224
0.6368
0.6479
0.6577
0.6663
0.6737
0.6801
0.6855
0.6907
0.6951
0.6988
A8
0.7767
0.7767
0.7767
0.7767
0.7767
0.7767
0.7767
0.7767
0.7767
0.7767
0.7767
0.7767
0.7767
0.7767
0.7767
0.7767
A8 - At
0.4418
0.2784
0.2239
0.1946
0.1719
0.1543
0.1399
0.1288
0.1190
0.1104
0.1030
0.0966
0.0912
0.0860
0.0816
0.0779
1/(A8 - At)
2.26
3.59
4.47
5.14
5.82
6.48
7.15
7.76
8.40
9.06
9.71
10.35
10.96
11.63
12.25
12.84
Table 4.C.12. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 3.00
x 10-4 M, [IO4?] = 1.50 x 10-3 M, pH = 6.26, I = 0.30 M and T = 25.0
o
C;
Time/s
0
40
80
120
160
200
240
280
At
0.3974
0.6291
0.6498
0.6668
0.6785
0.6874
0.6955
0.7023
A8
0.7803
0.7803
0.7803
0.7803
0.7803
0.7803
0.7803
0.7803
A8 - At
0.3829
0.1512
0.1305
0.1135
0.1018
0.0929
0.0848
0.0780
Ϯϭϭ
1/(A8 - At)
2.61
6.61
7.66
8.81
9.82
10.76
11.79
12.82
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
320
360
400
440
480
0.7082
0.7136
0.7175
0.7213
0.7246
0.7803
0.7803
0.7803
0.7803
0.7803
0.0721
0.0667
0.0628
0.0590
0.0557
13.87
14.99
15.92
16.95
17.95
Table 4.C.13. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 3.00
x 10-4 M, [IO4?] = 3.00 x 10-2 M, pH = 6.26, I = 0.30 M and T = 25.0
o
C;
Time/s
0
40
80
120
160
200
240
280
320
360
400
440
480
520
At
0.3860
0.5877
0.6432
0.6711
0.6912
0.7050
0.7151
0.7221
0.7276
0.7325
0.7364
0.7399
0.7426
0.7450
A8
0.7781
0.7781
0.7781
0.7781
0.7781
0.7781
0.7781
0.7781
0.7781
0.7781
0.7781
0.7781
0.7781
0.7781
A8 - At
0.3921
0.1904
0.1349
0.1070
0.0869
0.0731
0.0630
0.0560
0.0505
0.0456
0.0417
0.0382
0.0355
0.0331
1/(A8 - At)
2.55
5.25
7.41
9.35
11.51
13.68
15.87
17.86
19.80
21.93
23.98
26.18
28.17
30.21
Table 4.C.14. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 3.00
x 10-4 M, [IO4?] = 6.00 x 10-2 M, pH = 6.26, I = 0.30 M and T = 25.0
o
C;
Time/s
0
20
At
0.4263
0.5709
A8
0.8010
0.8010
A8 - At
0.3747
0.2301
ϮϭϮ
1/(A8 - At)
2.67
4.35
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
40
60
80
100
120
140
160
180
200
220
240
0.6436
0.6802
0.7029
0.7196
0.7318
0.7402
0.7467
0.7524
0.7571
0.7606
0.7638
0.8010
0.8010
0.8010
0.8010
0.8010
0.8010
0.8010
0.8010
0.8010
0.8010
0.8010
0.1574
0.1208
0.0981
0.0814
0.0692
0.0608
0.0543
0.0486
0.0439
0.0404
0.0372
6.35
8.28
10.19
12.29
14.45
16.45
18.42
20.58
22.78
24.75
26.88
Table 4.C.15. Summary table for the variation of k2 with [IO4?] at
[CrIIIdtpa(H2O)2-] = 3.00 x 10-4 M, pH = 6.26, I = 0.30 M and T = 25.0
o
C;
102[IO4?], M
0.50
0.70
1.00
1.50
3.00
6.00
103k2, M-1s-1
7.75 ± 0.03
11.55 ± 0.04
16.30 ± 0.03
25.72 ± 0.09
52.02 ± 0.10
102.67 ± 0.40
10k3, M-2s-1
15.50
16.50
16.30
17.15
17.34
17.11
Average = 16.65 ±
0.07
12.0
10.0
6.0
Ϯϭϯ
2
-1
10 k2, M s
-1
8.0
4.0
2.0
0.0
0.0
1.0
2.0
3.0
2
4.0
-
10 [IO4 ], M
5.0
6.0
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.65. Variation of k2 with [IO4?] at [CrIIIdtpa(H2O)2-] = 3.00 x 10-4
M, pH = 6.26, I = 0.30 M and T = 25.0 oC.
4.C.3.3 Effect of hydrogen ion concentration
The effect of [H+] on the reaction rate was investigated over the pH
range 5.56 – 8.56 under constant reaction conditions. The kinetic data
for the effect of pH on the third order rate constants, k3, are given in
Tables 4.C.16 – 4.C.30. Results are summarized in Table 4.C.31. The
dependence of k3 on [H+] was found to fit a polynomial of the second
degree, as shown in Fig. 4.66 (r2 = 0.999). The dependence of k3 on
[H+] is thus described by eq. (4.11);
1/k3 = a + b[H+] + c[H+]2
(4.11)
Table 4.C.16 Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 3.00 x
10-4 M, [IO4?] = 6.00 x 10-3 M, pH = 5.56, I = 0.30 M and T = 25.0 oC;
Time/s
0
120
240
At
0.0976
0.1582
0.1894
A8
0.5138
0.5138
0.5138
A8 - At
0.4162
0.3556
0.3244
Ϯϭϰ
1/(A8 - At)
2.40
2.81
3.08
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
360
480
600
720
840
960
1080
1200
1320
1440
1560
1680
1800
1920
0.2151
0.2352
0.2561
0.2725
0.2866
0.2988
0.3109
0.3208
0.3307
0.3396
0.3478
0.3543
0.3619
0.3669
0.5138
0.5138
0.5138
0.5138
0.5138
0.5138
0.5138
0.5138
0.5138
0.5138
0.5138
0.5138
0.5138
0.5138
0.2987
0.2786
0.2577
0.2413
0.2272
0.2150
0.2029
0.1930
0.1831
0.1742
0.1660
0.1595
0.1519
0.1469
3.35
3.59
3.88
4.14
4.40
4.65
4.93
5.18
5.46
5.74
6.02
6.27
6.58
6.81
Table 4.C.17. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 3.00
x 10-4 M, [IO4?] = 6.00 x 10-3 M, pH = 5.77, I = 0.30 M and T = 25.0
o
C;
Time/s
At
A8
A8 - At
1/(A8 - At)
0
0.0710
0.5117
0.4407
2.27
120
0.1715
0.5117
0.3402
2.94
240
0.2231
0.5117
0.2886
3.47
360
0.2582
0.5117
0.2535
3.94
480
0.2882
0.5117
0.2235
4.47
600
0.3111
0.5117
0.2006
4.99
720
0.3307
0.5117
0.1810
5.52
840
0.3464
0.5117
0.1653
6.05
960
0.3582
0.5117
0.1535
6.51
1080
0.3699
0.5117
0.1418
7.05
1200
0.3801
0.5117
0.1316
7.60
1320
0.3881
0.5117
0.1236
8.09
1440
0.3955
0.5117
0.1162
8.61
III
Table 4.C.18. Kinetic data for the reaction at [Cr dtpa(H2O)2-] = 3.00
x 10-4 M, [IO4?] = 6.00 x 10-3 M, pH = 5.95, I = 0.30 M and T = 25.0
o
C;
Ϯϭϱ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Time/s
0
40
80
120
160
200
240
280
320
360
400
440
480
520
560
600
640
680
At
0.0867
0.1934
0.2262
0.2501
0.2721
0.2912
0.3071
0.3198
0.3318
0.3415
0.3520
0.3609
0.3682
0.3757
0.3821
0.3885
0.3941
0.3991
A8
0.5245
0.5245
0.5245
0.5245
0.5245
0.5245
0.5245
0.5245
0.5245
0.5245
0.5245
0.5245
0.5245
0.5245
0.5245
0.5245
0.5245
0.5245
A8 - At
0.4378
0.3311
0.2983
0.2744
0.2524
0.2333
0.2174
0.2047
0.1927
0.1830
0.1725
0.1636
0.1563
0.1488
0.1424
0.136
0.1304
0.1254
1/(A8 - At)
2.28
3.02
3.35
3.64
3.96
4.29
4.60
4.89
5.19
5.46
5.80
6.11
6.40
6.72
7.02
7.35
7.67
7.97
Table 4.C.19. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 3.00
x 10-4 M, [IO4?] = 6.00 x 10-3 M, pH = 6.22, I = 0.30 M and T = 25.0
o
C;
Time/s
0
40
80
120
160
200
240
280
320
360
400
440
At
0.1732
0.3157
0.3636
0.3993
0.4263
0.4488
0.4666
0.4816
0.4942
0.5043
0.5126
0.5209
A8
0.6353
0.6353
0.6353
0.6353
0.6353
0.6353
0.6353
0.6353
0.6353
0.6353
0.6353
0.6353
A8 - At
0.4621
0.3196
0.2717
0.2360
0.2090
0.1865
0.1687
0.1537
0.1411
0.1310
0.1227
.01144
Ϯϭϲ
1/(A8 - At)
2.16
3.13
3.68
4.24
4.78
5.36
5.93
6.51
7.09
7.63
8.15
8.74
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.C.20. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 3.00
x 10-4 M, [IO4?] = 6.00 x 10-3 M, pH = 6.52, I = 0.30 M and T = 25.0
o
C;
Time/s
0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
At
0.1734
0.2776
0.3417
0.3848
0.4176
0.4432
0.4623
0.4805
0.4954
0.5085
0.5189
0.5278
0.5361
0.5435
0.5496
0.5547
A8
0.6542
0.6542
0.6542
0.6542
0.6542
0.6542
0.6542
0.6542
0.6542
0.6542
0.6542
0.6542
0.6542
0.6542
0.6542
0.6542
A8 - At
0.4808
0.3766
0.3125
0.2694
0.2366
0.2110
0.1919
0.1737
0.1588
0.1457
0.1353
0.1264
0.1181
0.1107
0.1046
0.0995
1/(A8 - At)
2.08
2.66
3.20
3.71
4.23
4.74
5.21
5.76
6.30
6.86
7.39
7.91
8.47
9.03
9.56
10.05
Table 4.C.21. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 3.00
x 10-4 M, [IO4?] = 6.00 x 10-3 M, pH = 6.66, I = 0.30 M and T = 25.0
o
C;
Time/s
0
40
80
120
160
200
240
At
0.2436
0.3799
0.4692
0.5156
0.5505
0.5696
0.5855
A8
0.6867
0.6867
0.6867
0.6867
0.6867
0.6867
0.6867
A8 - At
0.4431
0.3068
0.2175
0.1711
0.1362
0.1171
0.1012
Ϯϭϳ
1/(A8 - At)
2.26
3.26
4.60
5.84
7.34
8.54
9.88
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
280
0.5986
0.6867
0.0881
11.35
320
0.6078
0.6867
0.0789
12.67
360
0.6144
0.6867
0.0723
13.83
400
0.6211
0.6867
0.0656
15.24
440
0.6261
0.6867
0.0606
16.50
480
0.6309
0.6867
0.0558
17.92
520
0.6347
0.6867
0.0520
19.23
560
0.6378
0.6867
0.0489
20.45
III
Table 4.C.22. Kinetic data for the reaction at [Cr dtpa(H2O)2-] = 3.00
x 10-4 M, [IO4?] = 6.00 x 10-3 M, pH = 6.84, I = 0.30 M and T = 25.0
o
C;
Time/s
0
40
80
120
160
200
240
280
320
360
400
440
480
520
At
0.2753
0.3983
0.5169
0.5748
0.6084
0.6309
0.6447
0.6561
0.6644
0.6717
0.6769
0.6814
0.6851
0.6880
A8
0.7283
0.7283
0.7283
0.7283
0.7283
0.7283
0.7283
0.7283
0.7283
0.7283
0.7283
0.7283
0.7283
0.7283
A8 - At
0.4530
0.3300
0.2114
0.1535
0.1199
0.0974
0.0836
0.0722
0.0639
0.0566
0.0514
0.0469
0.0432
0.0403
1/(A8 - At)
2.21
3.03
4.73
6.51
8.34
10.27
11.96
13.85
15.65
17.67
19.46
21.32
23.15
24.81
Table 4.C.23. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 3.00
x 10-4 M, [IO4?] = 6.00 x 10-3 M, pH = 6.91, I = 0.30 M and T = 25.0
o
C;
Time/s
0
60
120
At
0.1976
0.4656
0.6183
A8
0.7768
0.7768
0.7768
A8 - At
0.5792
0.3112
0.1585
Ϯϭϴ
1/(A8 - At)
1.73
3.21
6.31
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
180
240
300
360
420
480
540
600
660
720
780
840
0.6698
0.6958
0.7117
0.7227
0.7308
0.7365
0.7407
0.7444
0.7472
0.7497
0.7518
0.7536
0.7768
0.7768
0.7768
0.7768
0.7768
0.7768
0.7768
0.7768
0.7768
0.7768
0.7768
0.7768
0.1070
0.0810
0.0651
0.0541
0.0460
0.0403
0.0361
0.0324
0.0296
0.0271
0.0250
0.0232
9.35
12.35
15.36
18.48
21.74
24.81
27.70
30.86
33.78
36.90
40.00
43.10
Table 4.C.24. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 3.00
x 10-4 M, [IO4?] = 6.00 x 10-3 M, pH = 7.02, I = 0.30 M and T = 25.0
o
C;
Time/s
0
60
120
180
240
300
360
420
480
540
600
660
720
780
840
At
0.2378
0.5542
0.6806
0.7195
0.7418
0.7556
0.7647
0.7713
0.7762
0.7799
0.7830
0.7853
0.7876
0.7893
0.7908
A8
0.8108
0.8108
0.8108
0.8108
0.8108
0.8108
0.8108
0.8108
0.8108
0.8108
0.8108
0.8108
0.8108
0.8108
0.8108
A8 - At
0.5730
0.2566
0.1302
0.0913
0.0690
0.0552
0.0461
0.0395
0.0346
0.0309
0.0278
0.0255
0.0232
0.0215
0.0200
Ϯϭϵ
1/(A8 - At)
1.75
3.90
7.68
10.95
14.49
18.12
21.69
25.32
28.90
32.36
35.97
39.22
43.10
46.51
50.00
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.C.25. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 3.00
x 10-4 M, [IO4?] = 6.00 x 10-3 M, pH = 7.36, I = 0.30 M and T = 25.0
o
C;
Time/s
At
A8
A8 - At
1/(A8 - At)
0
0.4076
0.8174
0.4098
2.44
30
0.5347
0.8174
0.2827
3.54
60
0.6298
0.8174
0.1876
5.33
90
0.6844
0.8174
0.1330
7.52
120
0.7101
0.8174
0.1073
9.32
150
0.7293
0.8174
0.0881
11.35
180
0.7425
0.8174
0.0749
13.35
210
0.7533
0.8174
0.0641
15.60
240
0.7611
0.8174
0.0563
17.76
270
0.7672
0.8174
0.0502
19.92
300
0.7723
0.8174
0.0451
22.17
330
0.7764
0.8174
0.0410
24.39
360
0.7794
0.8174
0.0380
26.32
390
0.782
0.8174
0.0354
28.25
420
0.7846
0.8174
0.0328
30.49
450
0.7870
0.8174
0.0304
32.89
480
0.7889
0.8174
0.0285
35.09
III
Table 4.C.26. Kinetic data for the reaction at [Cr dtpa(H2O)2-] = 3.00
x 10-4 M, [IO4?] = 6.00 x 10-3 M, pH = 7.47, I = 0.30 M and T = 25.0
o
C;
Time/s
0
30
60
90
120
150
180
210
240
270
300
330
At
0.3614
0.4644
0.6338
0.7049
0.7366
0.7572
0.7709
0.7808
0.7882
0.7939
0.7983
0.8025
A8
0.8404
0.8404
0.8404
0.8404
0.8404
0.8404
0.8404
0.8404
0.8404
0.8404
0.8404
0.8404
A8 - At
0.4790
0.3760
0.2066
0.1355
0.1038
0.0832
0.0695
0.0596
0.0522
0.0465
0.0421
0.0379
ϮϮϬ
1/(A8 - At)
2.09
2.66
4.84
7.38
9.63
12.02
14.39
16.78
19.16
21.51
23.75
26.39
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
360
390
420
450
0.8054
0.8081
0.8103
0.8124
0.8404
0.8404
0.8404
0.8404
0.0350
0.0323
0.0301
0.0280
28.57
30.96
33.22
35.71
Table 4.C.27. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 3.00
x 10-4 M, [IO4?] = 6.00 x 10-3 M, pH = 7.73, I = 0.30 M and T = 25.0
o
C;
Time/s
0
60
120
180
240
300
360
420
480
540
600
660
720
780
At
0.4743
0.7351
0.7902
0.8091
0.8217
0.8296
0.8350
0.8389
0.8421
0.8444
0.8464
0.8480
0.8491
0.8503
A8
0.8640
0.8640
0.8640
0.8640
0.8640
0.8640
0.8640
0.8640
0.8640
0.8640
0.8640
0.8640
0.8640
0.8640
A8 - At
0.3897
0.1289
0.0738
0.0549
0.0423
0.0344
0.0290
0.0251
0.0219
0.0196
0.0176
0.0160
0.0149
0.0137
1/(A8 - At)
2.57
7.76
13.55
18.21
23.64
29.07
34.48
39.84
45.66
51.02
56.82
62.50
67.11
72.99
Table 4.C.28. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 3.00
x 10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 8.02, I = 0.30 M and T = 25.0
o
C;
Time/s
0
60
120
180
240
At
0.4281
0.7081
0.7747
0.8005
0.8151
A8
0.8709
0.8709
0.8709
0.8709
0.8709
A8 - At
0.4428
0.1628
0.0962
0.0704
0.0558
ϮϮϭ
1/(A8 - At)
2.26
6.14
10.40
14.20
17.92
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
300
360
420
480
540
600
660
720
0.8248
0.8316
0.8367
0.8404
0.8436
0.8460
0.8482
0.8500
0.8709
0.8709
0.8709
0.8709
0.8709
0.8709
0.8709
0.8709
0.0461
0.0393
0.0342
0.0305
0.0273
0.0249
0.0227
0.0209
21.69
25.45
29.24
32.79
36.63
40.16
44.05
47.85
Table 4.C.29. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 3.00
x 10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 8.23, I = 0.30 M and T = 25.0
o
C;
Time/s
0
60
120
180
240
300
360
420
480
540
600
660
720
At
0.4421
0.6807
0.7691
0.8001
0.8151
0.8251
0.8325
0.8374
0.8416
0.8446
0.8472
0.8493
0.8509
A8
0.8714
0.8713
0.8713
0.8713
0.8713
0.8713
0.8713
0.8713
0.8713
0.8713
0.8713
0.8713
0.8713
A8 - At
0.4293
0.1906
0.1022
0.0712
0.0562
0.0462
0.0388
0.0339
0.0297
0.0267
0.0241
0.0220
0.0204
1/(A8 - At)
2.33
5.25
9.78
14.04
17.79
21.65
25.77
29.50
33.67
37.45
41.49
45.45
49.02
Table 4.C.30. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 3.00
x 10-4 M, [IO4?] = 4.00 x 10-3 M, pH = 8.56, I = 0.30 M and T = 25.0
o
C;
ϮϮϮ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Time/s
0
60
120
180
240
300
360
420
480
540
600
660
720
At
0.4193
0.6857
0.7706
0.8005
0.8161
0.8268
0.8335
0.8388
0.8425
0.8455
0.8481
0.8502
0.8519
A8
0.8717
0.8717
0.8717
0.8717
0.8717
0.8717
0.8717
0.8717
0.8717
0.8717
0.8717
0.8717
0.8717
A8 - At
0.4524
0.1860
0.1011
0.0712
0.0556
0.0449
0.0382
0.0329
0.0292
0.0262
0.0236
0.0215
0.0198
1/(A8 - At)
2.21
5.38
9.89
14.04
17.99
22.27
26.18
30.40
34.25
38.17
42.37
46.51
50.51
Table 4.C.31. Variation of kobs with pH at [CrIIIdtpa(H2O)2-] = 2.00 x
10-4 M, [IO4?] = 6.00 x 10-3 M, I = 0.30 M and T = 25.0 oC;
pH
108[H+],
M
5.56
275.00
5.77
170.00
5.95
112.00
6.22
60.30
6.52
30.20
6.66
21.90
6.84
14.50
103k2 M-1s-1
2.22 ±
0.01
4.30 ±
0.01
7.70 ±
0.04
14.09 ±
0.04
26.51 ±
0.10
33.24 ±
0.07
45.86 ±
0.08
10k3, M2 -1
s
102/k3, M2s
3.70
270.27
7.17
139.53
12.83
77.92
23.48
42.58
44.18
22.63
55.40
18.05
76.43
13.08
ϮϮϯ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
6.91
12.30
7.02
9.55
7.36
4.37
7.47
3.39
7.73
2.00
8.02
0.96
8.23
0.59
8.56
0.28
51.12 ±
0.10
59.11 ±
0.20
70.59 ±
0.30
78.92 ±
0.30
90.75 ±
0.40
62.59 ±
0.20*
66.01 ±
0.30*
67.91 ±
0.10*
85.20
11.74
98.52
10.15
117.65
8.50
131.53
7.60
151.25
6.61
156.48
6.39
165.03
6.06
169.78
5.89
Values marked with asterisk were obtained by using [IO4?] = 4.00 x 103
M.
3.00
2.50
2
1/k3, M s
2.00
1.50
1.00
0.50
0.00
0.0
5.0
10.0
15.0
ϮϮ
7ϰ +
10 [H ], M
20.0
25.0
30.0
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 4.66. Polynomial fit of the second degree of 1/k3 versus [H+] at
25.0 oC.
4.C.3.4 Effect of temperature on the rate of the reaction
The dependence of k2 on temperature was investigated over the range
20.0 – 40.0 oC at fixed [Cr(III)], [IO4?], pH and ionic strength. Results
are presented in Tables 4.C.32 – 4.C.35. Table 4.C.36 shows the
calculation for Erying equation. Plot of ln(k2/T) vs 1/T is shown in
Fig. 4.67. The value of ? H* is determined as 28.8 ± 0.1 kJ mol-1. The
entropy of activation is calculated as -125.9 ± 4.4 J mol-1 K-1.
Table 4.C.32. Kinetic data for the oxidation of [CrIIIdtpa(H2O)]2- at
[CrIIIdtpa(H2O)2-] = 2.50 x 10-4 M, [IO4?] = 5.0 x 10-3 M, pH = 6.15 and
I = 0.30 M, T = 20 oC;
Time/s
0
60
120
At
0.0562
0.1592
0.2555
A8
0.6719
0.6719
0.6719
A8 - At
0.6157
0.5127
0.4164
ϮϮϱ
1/(A8 - At)
1.62
1.95
2.40
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
180
240
300
360
420
480
540
600
660
720
780
0.3177
0.3661
0.3978
0.4242
0.4472
0.4653
0.4811
0.4941
0.5064
0.5163
0.5251
0.6719
0.6719
0.6719
0.6719
0.6719
0.6719
0.6719
0.6719
0.6719
0.6719
0.6719
0.3542
0.3058
0.2741
0.2477
0.2247
0.2066
0.1908
0.1778
0.1655
0.1556
0.1468
2.82
3.27
3.65
4.04
4.45
4.84
5.24
5.62
6.04
6.43
6.81
Table 4.C.33. Kinetic data for the oxidation of [CrIIIdtpa(H2O)]2- at
[CrIIIdtpa(H2O)2-] = 2.50 x 10-4 M, [IO4?] = 5.0 x 10-3 M, pH = 6.15 and
I = 0.30 M, T = 25 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
660
720
At
0.1014
0.2837
0.3593
0.4093
0.442
0.4719
0.4926
0.5096
0.5247
0.5366
0.5468
0.5568
0.5649
A8
0.6844
0.6844
0.6844
0.6844
0.6844
0.6844
0.6844
0.6844
0.6844
0.6844
0.6844
0.6844
0.6844
A8 - At
0.5830
0.4007
0.3251
0.2751
0.2424
0.2125
0.1918
0.1748
0.1597
0.1478
0.1376
0.1276
0.1195
1/(A8 - At)
1.72
2.50
3.08
3.64
4.13
4.71
5.21
5.72
6.26
6.77
7.27
7.84
8.37
Table 4.C.34. Kinetic data for the oxidation of [CrIIIdtpa(H2O)]2- at
[CrIIIdtpa(H2O)2-] = 2.50 x 10-4 M, [IO4?] = 5.0 x 10-3 M, pH = 6.15 and
I = 0.30 M, T = 30 oC;
ϮϮϲ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Time/s
0
60
120
180
240
300
360
420
480
540
600
660
At
0.0568
0.1867
0.3109
0.3824
0.4353
0.4727
0.4981
0.5221
0.5385
0.5523
0.5639
0.5733
A8
0.6909
0.6909
0.6909
0.6909
0.6909
0.6909
0.6909
0.6909
0.6909
0.6909
0.6909
0.6909
A8 - At
0.6341
0.5042
0.3800
0.3085
0.2556
0.2182
0.1928
0.1688
0.1524
0.1386
0.1270
0.1176
1/(A8 - At)
1.58
1.98
2.63
3.24
3.91
4.58
5.19
5.92
6.56
7.22
7.87
8.50
Table 4.C.35. Kinetic data for the oxidation of [CrIIIdtpa(H2O)]2- at
[CrIIIdtpa(H2O)2-] = 2.50 x 10-4 M, [IO4?] = 5.0 x 10-3 M, pH = 6.15 and
I = 0.30 M, T = 40 oC;
Time/s
0
80
160
240
320
400
480
560
640
720
800
At
0.0677
0.1449
0.3594
0.4598
0.5099
0.5452
0.5658
0.5825
0.5939
0.6036
0.6112
A8
0.6801
0.6801
0.6801
0.6801
0.6801
0.6801
0.6801
0.6801
0.6801
0.6801
0.6801
A8 - At
0.6124
0.5352
0.3207
0.2203
0.1702
0.1349
0.1143
0.0976
0.0862
0.0765
0.0689
ϮϮϳ
1/(A8 - At)
1.63
1.87
3.12
4.54
5.88
7.41
8.75
10.25
11.60
13.07
14.51
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.C.36. Variation of k3 with temperature;
T, K
103/T, K-1
k3, M-1s-1
103(k2/T)
ln(k2/T)
4.58
-5.38
5.91
-5.13
7.22
-4.93
11.29
-4.48
1.34 ±
293
3.41
0.01
1.76 ±
298
3.36
0.01
2.19 ±
303
3.30
0.01
3.53 ±
313
3.20
0.02
-9.80
ln(k2/T)
-10.00
-10.20
-10.40
-10.60
-10.80
3.15
3.23
3.30
3
-1
10 /T, K
Fig. 4.67. Plot of Erying equation
ϮϮϴ
3.38
3.45
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
4.C.3.5 Iodate effect
Tables 4.C.37 – 4.C.38, show that when IO3? was added to the reaction
mixture, the rate of oxidation did not change. k2 was determined in the
presence and absence of IO3? as (3.48 ± 0.03) x 10-2 M-1s-1 and (3.49 ±
0.03) x 10-2 M-1s-1, respectively.
Table 4.C.37. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 1.00
x 10-4 M, [IO4?] = 0.01 M, pH = 6.74, I = 0.30 M and T = 25.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
At
0.1481
0.3006
0.3378
0.3566
0.3696
0.3788
0.3858
0.3913
0.3959
0.3998
0.4030
A8
0.4412
0.4412
0.4412
0.4412
0.4412
0.4412
0.4412
0.4412
0.4412
0.4412
0.4412
A8 - At
0.2931
0.1406
0.1034
0.0846
0.0716
0.0624
0.0554
0.0499
0.0453
0.0414
0.0382
ϮϮϵ
1/(A8 - At)
3.41
7.11
9.67
11.82
13.97
16.03
18.05
20.04
22.08
24.15
26.18
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Table 4.C.38. Kinetic data for the reaction at [CrIIIdtpa(H2O)2-] = 1.00
x 10-4 M, [IO4?] = 0.01 M, [IO3?] = 2.00 x 10-3 M, pH = 6.74, I = 0.30
M and T = 25.0 oC;
Time/s
0
60
120
180
240
300
360
420
480
540
600
At
0.1644
0.3169
0.3508
0.3715
0.3827
0.3913
0.3979
0.4041
0.4086
0.4127
0.4159
A8
A8 - At
0.4536
0.2892
0.4536
0.1367
0.4536
0.1028
0.4536
0.0821
0.4536
0.0709
0.4536
0.0623
0.4536
0.0557
0.4536
0.0495
0.4536
0.0450
0.4536
0.0409
0.4536
0.0377
Chapter(V)
1/(A8 - At)
3.46
7.32
9.73
12.18
14.10
16.05
17.95
20.20
22.22
24.45
26.53
5. Discussion
5.1 cis-[CrIII(phen)2(H2O)2]3+ complex
The oxidation of this complex by periodate ion has been shown, even
in the presence of excess oxidant concentration, to produce a relatively
stable [CrV(phen)2(O)2]+ [46 - 48]. Periodate ion is known to be
involved in complex equilibria in aqueous solution as shown in eqs.
(5.1 – 5.3) [35]. Under the reaction conditions the most likely
periodate species are IO4?, H4IO6? and H5IO6. cis-[CrIII(phen)2(H2O)2]3+
complex also undergoes deprotonation-protonation equilibria as shown
in eqs. (5.4) and (5.5). The finding that the reaction rate increases with
ϮϯϬ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
increasing pH indicates that the deprotonated form of the Cr(III)
complex is the most reactive form of the complex. In almost all
oxidation reactions of Cr(III) species with IO4?, the deprotonated forms
are more readily oxidized [65,70]. The hydroxo forms of these species
are structurally intermediate between the aqua reactants and the oxo
products. It is unlikely that the dihydroxochromium(III) is present in
any appreciable quantity at the pH range employed in this study.
H4IO6?
IO4? + 2H2O
KD = 40
(5.1)
H4IO6? + H+
K1 = 5 x 102
H5IO6
(5.2)
H4IO6?
H3IO6 2- + H+
K2 = 4.3 x 10-9
(5.3)
[CrIII(phen)2(H2O)2]3+
[CrIII(phen)2(H2O)(OH)]2+ + H+ K3
(5.4)
[CrIII(phen)2(H2O)(OH)]2+
[CrIII(phen)2(HO)2]+ + H+
(5.5)
Ϯϯϭ
K4
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
The most likely periodate species present in the pH range covered in
this study are, H5IO6, H4IO6? and IO4?. Since the reaction decreases
with decreasing pH it is unlikely that there is a reaction between H5IO6
and cis-[CrIII(phen)2(H2O)2]3+.
The mechanism of oxidation of
[CrIII(phen)2(H2O)2]3+ by IO4? may be represented by the reaction
sequence in eqs. (5.6 – 5.8). The reaction seems to involve one-step
two electron transfer. This seems to be supported by absence of
polymerization on acrylonitrile.
[CrIII(phen)2(H2O)2]3+ + IO4?
[CrIII(phen)2(H2O)2IO4]2+
K5
(5.6)
[CrIII(phen)2(H2O)(OH)]2+ + IO4?
[(phen)2(H2O)CrIIIOHIO4]+ K6
(5.7)
[(phen)2(H2O)CrIII–OH–IO4]+ ?
[CrV(phen)2(O)2]+ + IO3?+ H3O+ ket
(5.8)
The rate law in eq. (5.9) is derived from eq. (5.4) and eqs. (5.6 – 5.8).
Rate = ketK3K6[CrIII(phen)2(H2O)(OH)2+ ][IO4 ?]
(5.9)
ϮϯϮ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
If it is assumed that [Cr(III)]t represents all the chromium(III) species,
then, [Cr(III)]t = [CrIII(phen)2(H2O)23+ ] + [CrIII(phen)2(H2O)(OH)2+]+
[CrIII(phen)2(H2O)2IO42+] + [(phen)2(H2O)CrIIIOHIO4+]
(5.10) [Cr(III)]t = [CrIII(phen)2(H2O)(OH)2+]{1 + [H+]/K3 +
K5[H+][IO4?] / K3 + K6[IO4?]}(5.11)
Substituting for [CrIII(phen)2(H2O)(OH)2+] from eq. (5.11) in eq. (5.9)
we obtain eq. (5.12).
Rate = ket K3K6[Cr(III)]t[IO4?] /{K3 + [H+] + K5[H+][IO4?] +
K3K6[IO4?]} (5.12)
Since the reaction is first order in [Cr(III)]t the pseudo first order rate
constant, kobs is given by eq. (5.13).
kobs = ket K3K6[IO4?] /{K3 + [H+] + K5[H+][IO4?] + K3K6[IO4?]}
(5.13)
eq. (5.13) is identical to the experimental rate law given by eq. (4.2)
where, a = ket K3K6, b = (K3 + [H+]) and c = (K5[H+] + K3K6)
Taking the reciprocal of eq. (5.13) gives eq. (5.14) which on plotting
1/kobs vs 1/[IO4?] gives a straight line with an intercept I1 and a slope
S1.
Ϯϯϯ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
1/ kobs = (K5[H+] + K3K6) / (ket K3K6) + (K3 + [H+]) / ket K3K6[IO4?]
(5.14)
From eq. (5.14) the intercept I1 and the slope S1 are given by eqs.
(5.15) and (5.16), respectively. Values of I1 and S1 at different pH
values and temperatures are collected in Table 4.A.127.
I1 = (K5[H+] + K3K6) / (ket K3K6)
(5.15)
S1 = (K3 + [H+]) / ket K3K6
(5.16)
Both I1 and S1 depend on [H+] as shown in eqs. (5.15) and (5.16). Plots
of both I1 and S1 vs [H+] are linear as shown in Fig. 4.48 and 4.49 (at
40.0 oC). From eq. (4.15) the intercept I2 = 1/ ket and the slope S2 = K5
/ketK3K6. From eq. (5.16) the slope I3 = 1/ ketK6 and S3 = 1/ ketK3K6.
The values of K3 at various temperatures are calculated from I3/S3,
whereas the values of K5 and K6 at several temperatures are calculated
from S2/S3 and I2/I3 respectively.
The value of pK3 for [CrIII(phen)2(H2O)2]3+ complex is obtained from
sigmoidal plot of k2 vs pH, Fig. 5.1, as 3.82 ± 0.45. pK3 can also be
obtained from -log K3 at 25.0 oC as 3.90 ± 0.50. This value is in
Ϯϯϰ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
excellent agreement with the value of 3.82 obtained from the
sigmoidal plot. These two values are in agreement with the literature
value [75]. The slight difference between the literature value (3.4) and
the experimental values may be attributed to the variation in ionic
strength.
1.5
1.2
k2, M-1 s-1
0.9
0.6
0.3
0.0
2.8
3.2
3.6
4.0
4.4
pH
Fig. 5.1. Sigmoidal fitting of k2 vs pH for [CrIII(phen)2(H2O)2]3+
complex at I = 0.30 M and T = 25.0 oC.
Ϯϯϱ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
The enthalpies of formation of the pre-equilibrium processes ? H5 and
? H6, shown in eqs. (5.6) and (5.7), are calculated from plots of lnK5 vs
1/T and lnK6 vs 1/T respectively. The values of ? H5 and ? H6 are
calculated from the slopes of these plots as 6.62 ± 0.51 and 24.68 ±
2.17 kJ mol-1 respectively. The entropies ? S5 and ? S6 associated with
these processes are obtained from the intercepts as 79.2 ± 1.7 J K-1
mol-1 and 148.5 ± 7.2 J K-1 mol-1 respectively. The low value of ? H5
for the association between cis-[CrIII(phen)2(H2O)2]3+ and IO4? seems to
indicate that this process is probably an ion-pair formation rather than
a substitution process on periodate. It is well known that coordinated
water is a poor bridging ligand. The enthalpy and entropy of
activation, ? H? and ? S? , are determined using the Eyring equation as
14.2 ± 1.2 kJ mol-1 and -236.0 ± 24.4 J K-1 mol-1 respectively.
5.2 [CrIIIcdta(H2O)]? and [CrIIIdtpa(H2O)]2- complexes
It is known that edta and cdta ligands with chromium(III) can behave
as either hexadentate or pentadentate. In pentadentate complexes the
sixth position is occupied by H2O [78, 83]. In the [CrIIIdtpa(H2O)]2complex, it is reported that the ligand is pentadentate with one
iminodiacetate group being free with varying degrees of protonation at
Ϯϯϲ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
pH ˜ 4 [79]. The presence of an H2O bonded to chromium(III) seems
to be a necessary requirement for the oxidation of chromium(III) by
IO4? to a higher oxidation state. Indeed the hydroxo forms of all
chromium(III) species so far studied is more reactive than the aqua
forms. The hydroxo forms of the chromium(III) complexes would
have lower reduction potentials and are thus more readily oxidized and
are structurally intermediate between the aqua reactants and the oxo
products. It was previously reported that electron transfer involving
aqua ions resulting in the formation of oxo ions is often preceded by
hydrolysis [80].
With the exception of [CrIII(H2O)]3+ no other reaction between
chromium(III) species and IO4? have shown a second order dependence
on [Cr(III)]. The kinetics of the oxidation of the two complexes
[CrIIIcdta(H2O)]? and [CrIIIdtpa(H2O)]2- , to our knowledge, are the only
two other examples that have shown this very uncommon behaviour. It
is surprising that the kinetics of the closely related complex,
[CrIIIedta(H2O)]?, displayed only a first-order dependence on the
chromium(III) complex concentration. The difference in behaviour
may be related to the relative stabilities chromium(IV) and
chromium(V) species generated in the course of these reactions. Thus,
Ϯϯϳ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
when chromium(V) is more stable than chromium(IV) first order
kinetics is obeyed and when the opposite is true second order kinetics
is observed. In both processes, it seems that, the formation of the
unstable I(VI) is avoided.
The effect of [H+] on the reaction rate was investigated over the pH
range 5.52 – 7.44 and 5.56 – 8.56 for the [CrIIIcdta(H2O)]? and
[CrIIIdtpa(H2O)]2- complexes respectively under constant reaction
conditions. The kinetic data for the effect of pH on the third order rate
constants, k3, for both complexes, are given in Tables 4.B.28 and
4.C.31. The dependence of k3 on [H+] was found to fit a polynomial of
the second degree, for both chromium(III) complexes, as shown in
Figs. 4.58 and 4.66 (r2 = 0.999). The dependence of k3 on [H+] for both
complexes is thus described by eq. (4.7).
The values of a, b, and c were obtained from the polynomial fit of the
second degree for the oxidation of [CrIIIcdta(H2O)]? as (9.87 ± 0.39) x
10-2 M s, (6.34 ± 0.96) x 104 M s and (1.10 ± 0.54) x 1011 s,
respectively. The corresponding values for the [CrIIIdtpa(H2O)]2complex are (6.0 ± 0.43) x 10-2 M s, (4.72 ± 0.14) x 105 M s and (1.78
± 0.06) 1011 s, respectively.
Ϯϯϴ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
The observed kinetics of these two reactions may be described by the
reaction sequence (5.17 – 5.21).
H4IO6?
H3IO62- + H+
K1
(5.17)
[CrIIIL(H2O]n
[CrIIIL(OH]n- 1 + H
K2
(5.18)
[CrIIIL(OH]n- 1 + IO4?
[LCrIII-OH-IO4]n-2
K3
(5.19)
[LCrIII-OH-IO4]n- 2
+[CrIIIL(OH]n-1
[LCrIII-OH-IO4-OH-
CrIIIL]n- 3K4 (5.20)
2Cr(IV) + IO3? + H2O
[LCrIII-OH-IO4-OH-CrIIIL]n- 3
ket
(5.21)
2 Cr(IV) + 2I(VII)
2Cr(VI) + 2I(V)
fast
(5.21)
Since the reported value of K1 = 4.3 x 10- 9, periodate will
predominantly be present as IO4? or H4IO6? in the pH ranges covered in
Ϯϯϵ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
these reactions [35]. From the mechanism shown above the rate law
shown in eq. (5.22) is derived.
d[Cr(VI)]/dt = (ketK22K3K4[CrIIIL(H2O)n]2[I(VII)])/(K22 + 2K2[H+] +
[H+]2) (5.22)
The third order rate constant, k3, varies with [H+] according to eq.
(5.23). The dependence of 1/k3 vs [H+], for each chromium(III)
complex, is given by eq. (5.24). Eq. (5.24) has the same form as the
experimentally determined dependence of k3 on [H+] as given in eq.
(4.7). It is readily seen from eqs. (4.7) and (5.24) that a = 1/ ketK3K4, b
= 2/ ketK2K3K4 and c = 1/ ketK22K3K4.
k3
=
ketK22K3K4/(K22
+
2K2[H+]
+
[H+]2)
(5.23)
1/k3 = 1/ ketK3K4 + 2[H+]/ ketK2K3K4 + [H+]2/ ketK22K3K4
(5.24)
12.0
-2
k 3, M s
-1
9.0
6.0
3.0
ϮϰϬ
0.0
5.50
6.00
6.50
pH
7.00
7.50
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
Fig. 5.2. Sigmoidal fitting of k3 vs pH for [CrIIIcdta(H2O)]? complex
The
values
of
pK2
for
both
[CrIIIcdta(H2O)]?
and
[CrIIIdtpa(H2O)]2- complexes are obtained from sigmoidal plots of k3 vs
pH as 6.09 ± 0.04 and 6.93 ± 0.03, Figs 5.2 and 5.3, respectively.
From the relationships a/b = K2/2, a/c = K22 and b/c = 2K2 an average
value of pK2 = 6.02 ± 0.2 is calculated for the [CrIIIcdta(H2O)]?
complex. This is in fairly good agreement with the value of 6.09. From
similar calculations an average value of 6.24 ± 0.35 is calculated for
the [CrIIIdtpa(H2O)]2-
complex. The value of b/c for the
[CrIIIdtpa(H2O)]2- complex gives a value of pK2 = 6.66 which the
closest value to 6.93.
The values of ? H* are determined as 28.8 ± 0.1 kJ mol-1 and 34.1 ±
0.7 kJ mol-1 for the [CrIIIcdta(H2O)]? and [CrIIIdtpa(H2O)]2- complexes
respectively. This is consistent with our findings that the oxidation of
[CrIIIcdta(H2O)]? complex by IO4? is faster than the oxidation of
Ϯϰϭ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
[CrIIIdtpa(H2O)]2- complex by IO4?. The entropies of activation are
calculated as -147.9 ± 6.1 J mol-1 K-1 and -125.9 ± 4.4 J mol-1 K-1 for
the
[CrIIIcdta(H2O)]?
and
the
[CrIIIdtpa(H2O)]2-
complexes
respectively.
18.0
15.0
-2
k 3, M s
-1
12.0
9.0
6.0
3.0
0.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
pH
Fig. 5.3. Sigmoidal fitting of k3 vs pH for [CrIIIdtpa(H2O)]2- complex at
25.0 oC.
The relatively high negative values of ? S* for both complexes is in
agreement with the proposed mechanism in which two hydroxo
species of each complex associate with IO4? prior to electron transfer.
In conclusion the oxidation of the two complexes [CrIIIcdta(H2O)]? and
[CrIIIdtpa(H2O)]2- by IO4?
exhibited an uncommon second order
dependence on the chromium(III) complex. This has been interpreted
by invoking a mechanism in which two [CrIIIL(OH)]n are added
ϮϰϮ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
rapidly to IO4? forming a precursor complex. Concurrent two one
electron transfer within the precursor complex leads to the formation
of a chromium(IV) that is stabilized by the aminopolycarboxylate
ligand. The chromium(IV) is then rapidly oxidized by IO4? to the final
product, chromium(VI). The proposed mechanism is consistent with
inner-sphere electron transfer being the preferred pathway for
periodate ion oxidations.
Ϯϰϯ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
References
1. G. L. Miessler and D. A. Tarr, (Inorganic Chemistry), 3rd
edition, Prentice Hall, (2002) p 414.
2. R. G. Wilkins, (Kinetics and Mechanisms of Transition Metal
Complexes), 2nd edition, VCH Publishers, Inc., New York
(1991) p 257.
3. C. E. Housecraft, A. G. Sharpe (Inorganic Chemistry), 2nd
edition, Pearson Education Limited, England (2005) p 593.
4. E. U. Condon, Am. J. Phys., 15, 365 (1947).
5. R. A. Marcus, B. J. Zwolinski and H. Erying, J. Phys. Chem.,
58, 432 (1954).
6. R. A. Marcus, J. Phys. Chem., 24, 970 (1956).
7. W. F. Libby, J. Phys. Chem., 56, 863 (1952).
8. R. A. Marcus, J. Phys. Chem., 24, 966, 979 (1956).
9. R. A. Marcus, J. Phys. Chem., 43, 679 (1965).
10.R. A. Marcus N. Sutin, Biochim. Biophys. Acta, 811, 265
(1985).
Ϯϰϰ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
11.H. Taube “Electron Transfer Reactions of complex ions in
Solution” Academic, New York (1970).
12.A. Anderson and N. A. Bonner, J. Am. Chem. Soc., 76, 3826
(1954).
13.H. Taube and H. Mayers, J. Am. Chem. Soc., 76, 2103 (1954).
14.H. Taube and E. L. King, J. Am. Chem. Soc., 76, 4053 (1954).
15.H. Taube, H. Mayers, and R. L. Rich. J. Am. Chem. Soc., 75,
4118 (1953).
16.R. A. Whiteker and N. A. Davidson, J. Am. Chem. Soc., 75,
3081 (1953).
17.T. J. Conocchiolo, J. H. Nancollas and N, Sutin, J. Am. Chem.
Soc., 86, 1453 (1964).
18.H. Taube, J. Am. Chem. Soc., 77, 4481 (1955).
19.J. Hudis and R. W. Dodson, J. Am. Chem. Soc., 78, 911 (1956).
20.K. B. Wiberg, 55, 713 (1955).
21.W. L. Reynolds and R. Lumry, J. Chem. Phys., 23, 2560 (1955).
22.A. A. Frost and R. G. Pearson “Kinetics and Mechanism” John
Wiley and sons, New York p 202 (1953).
23.D. L. Leussing and I. M. Kolthof, J. Am. Chem. Soc., 75, 2476
(1953).
Ϯϰϱ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
24.F. S. Dainton, J. Chem. Soc., 1952 (1953).
25.G. J. Buist, in: C. H. Bamford, C. F. H. Tripper (Eds.),
Comprehensive Chemical Kinetics, Elsevier, Amsterdam, Vol.
6, pp. 435.
26.A. Y. Kasim, Y. Sulfab, Inorg. Chim. Acta. 24, 247 (1977).
27.M. H. Abu-Elenin, N. A. Al-Shatti, M. A. Hussein, Y. Sulfab,
Polyhedron, 9, 99 (1990).
28.M. A. Hussein, A. A. Abdel-Khalek, Y. Sulfab, J. Chem. Soc.
Dalton Trans., 317 (1981).
29.A. A. Abdel-Khalek, Y. Sulfab, J. Inorg. Nucl. Chem., 43, 3257
(1981).
30.R. M. Naik, A. Srivastava, A. K. Tiwari, S. B. S. Yadav, A. K.
Verma, J. Iran. Chem. Soc., 4, 63 (2007).
31.G. J. Buist and C. A. Bunton, J. Chem. Soc., 1406 (1956).
32.G. J. Buist, C. A. Bunton and J. Homas, J. Chem. Soc., 1099
(1966).
33.J. E. Scott and M. J. Tigwell, J. Biochem., 173, 103 (1978).
34.C.E. Crouthamel, A.M. Haves and D.S. Martin, J. Am. Chem.
Soc., 73, 82 (1951).
Ϯϰϲ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
35.C.E. Crouthamel, H. V. Meek, D.S. Martin and C. V. Banks, J.
Am. Chem. Soc., 71, 3031 (1949).
36.F. A. Cotton, G. Wilkinson “Advanced Inorganic Chemistry”,
3rd edition, John Wiley & Sons, New York, p 480 (1972).
37.R. M. Kross, H. M. Dogden and C. J. Nyman, Inorg. Chem., 7,
446 (1968).
38.C. C. Price and H. Kroll, J. Am. Chem. Soc., 60, 2726 (1938).
39.F. R. Duke, J. Am. Chem. Soc., 69, 3054 (1947).
40.F. J. Westhiemer, Chem. Rev., 45, 419 (1949).
41. K. B. Wiberg, Oxidation in Organic Chemistry, part A,
Academic Press, New York, N.Y. (1965).
42.J. T. Groves, W. J. Kruper, J. Am. Chem. Soc., 101, 7613
(1979).
43.Y. Sulfab, N. A. Al-Jallal, Transition Met. Chem., 29, 216
(2004).
44.T. L. Siddall, N. Miyaura, J. C. Huffman, J. K. Kochi, J. Chem.
Soc., Chem. Comm., 1185 (1983).
45.K. Sirinivasan, J. K. Kochi, Inorg. Chem., 24, 4671 (1985).
46.Y. Sulfab, N. I. Alshatti, M. A. Hussein, Inorg. Chim. Acta, 86,
L 59 (1984).
Ϯϰϳ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
47.Y. Sulfab, M. Nasreldin, Transition Met. Chem., 26, 147 (2001).
48.C. L. Weeks, A. Levina, C. T. Dillon, P. Turner, R. R. Fenton,
P. A. Lay, Inorg. Chem., 43, 7844 (2004).
49.M. Krumpolc, J. Rocek, J. Am. Chem. Soc., 101, 3206 (1979).
50.A. Malcolm, P. C. Ford, Coord. Chem. Rev., 47, 208 (2000).
51.A. Hori, T. Ozawa, H. Yoshida, Y. Imori, Y. Kuribayshi, E.
Nakano, N. Azuma, Inorg. Chim. Acta., 281, 207 (1998).
52.A. E. Meier-Callahan, H. B. Gray, Z. Gross, Inorg. Chem., 39,
3605 (2000).
53.R. A. Anderson, J. Am. Coll. Nutr., 16, 404 (1997).
54.J. B. Vincent, Acc. Chem. Res., 33, 503 (2000).
55.A. Y. Kassim, Y. Sulfab, Inorg. Chem., 20(2), 506 (1981).
56.F. R. El-Eziri, Y. Sulfab, Inorg. Chim. Acta, 25, 15 (1977).
57.H. A. Ewais, S. A. Ahmed and A. A. Abdel-Khalek, J. Chinese,
Chem. Soc., 51, 713 (2004).
58.A. A. Abdel- Khalek, M. M. Elsemongy, Bull. Chem. Soc. Jpn,
61. 4407 (1988).
59.A. A. Abdel-Khalek, A. A. Mohamed, H. A. Ewais, Transition
Met. Chem., 24(2), 233 (1999).
Ϯϰϴ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
60.A. A. Abdel-Khalek, E. M. Sayyah, H. A. Ewais, Transition
Met. Chem., 22, 375 (1997).
61.H. A. Ewais, M. A. Habib, S. A. K. Elroby, Transition Met.
Chem., 35(1), 73 (2010).
62.H. A Ewais, F. D. Dahman, A. A. Abdel-Khalek, Chem. Central
J., 3, 3 (2009).
63.H. A. Ewais, E. S. Khaled and A. A. Abdel-Khalek. Ind. J.
Chem., 40A, 410 (2001).
64.A. A. Abdel-Khalek, Transition Met. Chem., 16(2), 173 (1991).
65.A. A. Abdel- Khalek, E. M. Sayyah and E. H. Khaled.
Transition Met. Chem., 23(1), 37 (1998).
66.H. A. Ewais, M. K. Ismael, and A. A. Abdel-Khalek, J. Saudi
Chem. Soc., 13, 219 (2009).
67.M. K. Mishra, N. M. Misra, E-J. Chem., 8(2), 513 (2011).
68.N. A. Aljallal, Y. Sulfab, Transition Met. Chem., 8(1), 51
(1983).
69.S. S. Anis and M. A. Mansour, Transition Met. Chem., 26(6),
695 (2001).
70.O. Volarova and V. Holba, Collect. Czech. Chem. Commun., 46,
2503 (1981).
Ϯϰϵ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
71.H. A. Ewais, D. F. Al-Otaibi, and A. A. Abdel-Khalek, Bioing.
Reac. Mech., 6(1), 39 (2006).
72. A. M. Abdel-Hady, Transition Met. Chem., 25(4), 437 (2000).
73.A. A. Abdel-Khalek, Transition Met. Chem., 15(2), 112 (1990).
74.F. S. Head; H. A. Standing, J. Chem. Soc., 75, 5670 (1953).
75.R. G. Inskeep, J. Bjerrum, J. Acta Chem. Scand., 15, 62 (1961).
76.Z.
Markzenko,
“Separation
and
Spectrophotometric
Determination of Elements” Ellis Horwood Limited, England,
1st edition, (1986), p 235.
77.A. R. Selmer-Olsen, Anal. Chim. Acta, 26, 482 (1962).
78.S. Sander; T. Navratil; L. Novotny, Electroanalysis, 15, 1514
(2003).
79.R. Bucci; A.D. Magri; A. L. Magri; A. Napoli, Polyhedron, 19,
2421 (2000).
80.S. Kaizaki; M. Hayashi; K. Umakushi; S. Oor, Bull. Chem. Soc.
Jpn. 61, 3519 (1988).
81.K. D. Barker, K. A. Barnetta, S. M. Connella, J. W. Glaesera,
A. J. Wallacea, J. Wildsmitha, B. J. Herbertb, J. F. Wheeler,
N. A. F. Kane-Maguire, Inorg. Chim. Acta, 41, 316 (2001).
ϮϱϬ
Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark.
82.R. G. Inskeep, M. Benson, J. Inorg. Nucl. Chem., 20, 290
(1961).
83.J. G. Mason, J. M. Vander Meer, Inorg. Chem., 13, 2443 (1974).
Ϯϱϭ
© Copyright 2026 Paperzz