Modeling the Structure and Mechanism of Nickel Superoxide Dismutase
A dissertation presented to
the faculty of
the College of Arts and Sciences of Ohio University
In partial fulfillment
of the requirements for the degree
Doctor of Philosophy
Huaibo Ma
June 2011
© 2011 Huaibo Ma. All Rights Reserved.
2
This dissertation titled
Modeling the Structure and Mechanism of Nickel Superoxide Dismutase
by
HUAIBO MA
has been approved for
the Department of Chemistry and Biochemistry
and the College of Arts and Sciences by
Michael P. Jensen
Assistant Professor of Chemistry
Benjamin M. Ogles
Dean, College of Arts and Sciences
3
ABSTRACT
MA, HUAIBO, Ph.D., June 2011, Chemistry
Modeling the Structure and Mechanism of Nickel Superoxide Dismutase
Director of Dissertation: Michael P. Jensen
Superoxide dismutases are metalloenzymes that catalyze the disproportionation of
superoxide radical to hydrogen peroxide and molecular oxygen. By degrading superoxide
radicals, cells can avoid oxidative stress. Nickel-dependent superoxide dismutases
(NiSOD) were isolated from Streptomyces and structurally characterized just a couple of
years ago, and represent a new class of SOD. The unique active site geometry of NiSOD
involves changing from square planar Ni2+ to square pyramidal Ni3+. The mechanism at
NiSOD active center is supposed to involve two one-electron redox half-reactions of O2·to form O2 and H2O2, the same as known SODs. However, the details of nickel ligation
and proton transfer remain controversial.
This work will focus on modeling the structure and mechanism of NiSOD by
small-molecule complexes. Our work employed N3-tripod and S,S’-chelating ligands to
stabilize different nickel geometries to try to explain relationships among them.
Hydro(trispyrazoyl)borate (Tp) ligands were prepared to be the N3-tripod ligand. S,S′chelating organoxanthate (xan) and dithiocarbamate (dtc) were utilized to mimic the
dithiolate motif. These above ligands formed 4- and 5-coordinate Ni2+ complexes due to
“scorpionate” equilibrium between k2-Tp and k3-Tp binding modes, which provided
examples to model the reduced state in NiSOD. Our results demonstrated the existence of
an axial equilibrium in our Ni2+ complexes, and steric effects that affect this behavior.
Meanwhile, Co2+ complexes, isoelectronic to Ni3+, were also synthesized to compare to
the oxidized state of NiSOD.
Approved: _____________________________________________________________
Michael P. Jensen
Assistant Professor of Chemistry
4
To my deeply loved mother, Qin Zhang and father, Xinchao Ma.
5
ACKNOWLEDGMENTS
It’s always exciting to arrive at a certain phase at different times especially when
one is on the way of approaching his dream. At the moment of graduation soon, I want to
thank my family and friends for understanding what I have been doing and pursuing.
Also, I want to thank co-workers and faculty and staff from the Department of Chemistry
and Biochemistry. My graduate research work in the lab has become much easier with
generous support from these above people.
I appreciate very much my advisor Dr. Michael P. Jensen for offering me an
excellent opportunity of working together with him during past years. My research work
can not be finished without Jensen’s direction and help. Surrounded with a friendly
atmosphere, we extensively discussed research plans and issues in my work which
extremely helped me to better understand the goal of this project and appreciate methods
selected to solve corresponding problems. My research experience at Ohio University
will benefit my future research career without any doubts. Thank you, Dr. Jensen.
Again, I want to thank my deeply loved mother, Qin Zhang and father, Xinchao
Ma.
6
Table of Contents
Page
Abstract ...........................................................................................................................3
Dedication .......................................................................................................................4
Acknowledgments ...........................................................................................................5
List of Tables ...................................................................................................................8
List of Figures ............................................................................................................... 10
List of Schemes ............................................................................................................. 14
Chapter I: Introduction .................................................................................................. 15
Chapter II: Experimental Section................................................................................... 30
Chapter III: Scorpionate TpPh,Me Ligand Equilibria for Modeling Reduced NiSOD
Intermediates ................................................................................................................. 41
Chapter IV: Scorpionate Suppported Models of Nickel-dependent Superoxide Dismutase
...................................................................................................................................... 62
Chapter V: Solid State Spin Crossover of Ni2+ in a Bioinspired N3S2 Ligand Field ........ 84
Chapter VI: Protonation of Model Complexes ............................................................... 94
Chapter VII: Co2+N3S2 Complexes as Models for the Oxidized Ni3+N3S2 Active Site . 119
References ................................................................................................................... 138
Appendix A: Crystal Structure Data of Complex 1 ...................................................... 147
Appendix B: Crystal Structure Data of Complex 3 ...................................................... 150
Appendix C: Crystal Structure Data of Complex 5 ....................................................... 154
Appendix D: Crystal Structure Data of Complex 6 ....................................................... 158
Appendix E: Crystal Structure Data of Complex 7 ....................................................... 163
Appendix F: Crystal Structure Data of Complex 8 ....................................................... 168
Appendix G: Crystal Structure Data of Complex 9 ....................................................... 173
Appendix H: Crystal Structure Data of Complex 10 ..................................................... 177
Appendix I: Crystal Structure Data of Complex 11 ...................................................... 177
Appendix J: Crystal Structure Data of Complex 12 ...................................................... 183
Appendix K: Crystal Structure Data of Complex 13 ..................................................... 188
Appendix L: Crystal Structure Data of Complex 14 ..................................................... 192
Appendix M: Crystal Structure Data of Complex 15 .................................................... 196
7
Appendix N: Crystal Structure Data of Complex 16 ..................................................... 201
Appendix O: Crystal Structure Data of Complex 17 ..................................................... 205
Appendix P: Crystal Structure Data of Complex 18...................................................... 209
8
List of Tables
Page
Table 1: Wavelength(nm) and molar extinction coefficient (mM-1cm-1) for TpPh,MeNi2+
complexes in DCM ..................................................................................................... 48
Table 2: Selected chemical shifts (ppm) for TpPh,MeNi2+complexes in CDCl3 at 295 K
................................................................................................................................... 49
Table 3: Selected chemical shifts (ppm) for TpPh,MeNi2+1,2-dithiolene in CDCl3 at 295 K
................................................................................................................................... 53
Table 4: Selected bond lengths (Å) and angles (º) for complexes 5, 7 and 9................ 57
Table 5: Magnetic moments measured in CDCl3 at 295 K by Evans method. ............. 58
Table 6: Oxidation and reduction properties of modeling Ni2+ and Co2+ complexes. ... 61
Table 7: Selected bond lengths (Å) and angles (°) for complexes 1 and 3. .................. 80
Table 8: Wavelength(nm) and molar extinction coefficient (mM-1cm-1) for TpMe,MeNi2+
complexes in DCM. .................................................................................................... 81
Table 9: Selected chemical shifts (ppm) for TpMe,MeNi2+ complexes in CDCl3 at 295 K
................................................................................................................................... 82
Table 10: Summary of the X-ray crystal structure determinations for 10, 11, 12. ........ 92
Table 11: Summary of ligand field bond lengths and geometry. ................................. 93
Table 12: Selected bond lengths (Å) and angles (º) for complexes 6 and 8.................. 99
Table 13: Selected bond lengths (Å) and angles (º) for complexes 13 and 14 ............ 106
Table 14: Selected bond lengths (Å) and angles (º) for complex 18 .......................... 115
Table 15: Selected bond lengths (Å) and angles (º) for complexes 15, 16 and 17 ...... 125
9
Table 16: Selected chemical shifts (ppm) for TpPh,MeCo2+ complexes in CDCl3 at 295 K
................................................................................................................................. 130
Table 17: Wavelength(nm) and molar extinction coefficient (mM-1cm-1) for TpPh,MeCo2+
complexes in DCM ................................................................................................... 133
10
List of Figures
Page
Figure 1: X-ray structures of the active site in oxidized and photoreduced NiSOD ..... 19
Figure 2: UV-Visible-NIR spectra (CH2Cl2, 295 K) of TpPh,MeNiS2CNEt2 (green),
TpPh,MeNiS2CNPh2 (red), and TpPh,MeNiS2COEt (black) .............................................. 48
Figure 3: 1H NMR spectra (CDCl3, 295 K) of TpPh,MeNiS2CNEt2 (top),
TpPh,MeNiS2CNPh2 (middle), and TpPh,MeNiS2COEt (bottom) ...................................... 49
Figure 4: Solvents dependent 1H NMR spectra (295 K) of TpPh,MeNiS2CNEt2 in CDCl3
(top), CD3CN (middle) and toluene-d8 (bottom). ......................................................... 50
Figure 5: Variable temperature 1H NMR spectra of TpPh,MeNiS2CNPh2 in CDCl3 ....... 51
Figure 6: 1H NMR spectra (CDCl3, 295 K) of TpPh,MeNiS,S’-dithiolene ..................... 52
Figure 7: Perspective view of the molecular structure of complex 5 with the atom
labeling scheme .......................................................................................................... 54
Figure 8: Perspective view of the molecular structure of complex 7 with the atom
labeling scheme .......................................................................................................... 55
Figure 9: Perspective view of the molecular structure of complex 9 with the atom
labeling scheme .......................................................................................................... 56
Figure 10: Titration of TpPh,MeNiS2CNPh2 with CF3CO2H in CH2Cl2 at 20ºC ............. 59
Figure 11: UV-Visible-NIR spectra of TpPh,MeNiS2CNPh2, recorded in CH3CN at 10 K
intervals from 20 to 70ºC ............................................................................................ 60
Figure 12: Van’t Hoff plot for the axial base equilibrium of TpPh,MeNiS2CNPh2 shown in
Figure 11 .................................................................................................................... 60
11
Figure 13: Cyclic voltammograms of 5 (green) and 9 (black) ..................................... 61
Figure 14: Perspective view of the molecular structure of complex 1 (left) and 3 (right)
with the atom labeling scheme .................................................................................... 78
Figure 15: Overhead ball-and-stick views of 2’ and 1 and a side-on wireframe overlay
plot, emphasizing rotation of the organoxanthate chelates with respect to the N3
scorpionate faces ........................................................................................................ 78
Figure 16: Space-filling diagrams of 2’, 1, and 3 from an axial perspective toward the
open octahedral site, emphasizing the steric effects of 3-pyrazole substituents and
dithioacid chelate rotation on its accessibility ............................................................. 79
Figure 17: UV-Vis spectra (CH2Cl2, 295 K) of 2, 3 and 4 .......................................... 81
Figure 18: 1H NMR spectra of 1-4 (bottom to top, respectively). Peaks arising from the
3-5 pyrazole ring positions and solvent (s) are labeled ................................................ 82
Figure 19: Solid-state temperature-dependent magnetic susceptibility data for 1 ........ 83
Figure 20: Cyclic voltammograms of 1 (bottom) and 3 (top) ...................................... 83
Figure 21: Unit cell of TpPh,MeNiS2CNMe2 at 293 K .................................................. 90
Figure 22: ORTEP plots of TpPh,MeNiS2CNMe2 at 293 K (left column, 30% ellipsoids), at
123 K (center column, 50% ellipsoids) and overlays of the Ni1 and Ni2 structures at the
two temperatures (right column, least-squares alignments of B1/N4/N6 and B2/N11/N13)
................................................................................................................................... 90
Figure 23: Solid-state temperature-dependent magnetic susceptibility data (χT, left axis;
1/χ, right axis) for TpPh,MeNiS2CNMe2 ........................................................................ 91
12
Figure 24: Perspective view of the molecular structure of complex 6 with the atom
labeling scheme .......................................................................................................... 97
Figure 25: Perspective view of the molecular structure of complex 8 with the atom
labeling scheme .......................................................................................................... 98
Figure 26: Perspective view of the molecular structure of complex 13 with the atom
labeling scheme ........................................................................................................ 104
Figure 27: Perspective view of the molecular structure of complex 14 with the atom
labeling scheme ........................................................................................................ 105
Figure 28: 1H NMR spectra (CDCl3, 295 K) of TpPh,MeNiS2CNEt2, TpPh,MeNiS2CNPh2
and corresponding protonated by CF3COOH, respectively ........................................ 108
Figure 29: Perspective view of the molecular structure of complex 18 with the atom
labeling scheme ........................................................................................................ 114
Figure 30: Perspective view of the molecular structure of complex 15 with the atom
labeling scheme ........................................................................................................ 122
Figure 31: Perspective view of the molecular structure of complex 16 with the atom
labeling scheme ........................................................................................................ 123
Figure 32: Perspective view of the molecular structure of complex 17 with the atom
labeling scheme ........................................................................................................ 124
Figure 33: 1H NMR spectra (CDCl3, 295 K) of 15-17 and TpPh,MeCoCl (bottom to top,
respectively). ............................................................................................................ 130
Figure 34: UV-Visible-NIR spectra (CH2Cl2, 295 K) of 15, 16, and 17 .................... 132
Figure 35: EPR spectrum of 15 ................................................................................ 135
13
Figure 36: EPR spectrum of 16 ................................................................................ 136
Figure 37: EPR spectrum of 17 ................................................................................ 137
14
List of Schemes
Page
Scheme 1: Disproportion mechanism in NiSOD ......................................................... 19
Scheme 2: Ligand field splitting for d8 Ni2+ ................................................................ 22
Scheme 3: Representive synthetic model Ni2+N2S2 complexes.................................... 22
Scheme 4: Synthesis of Ni2+N3S2 model complexes.................................................... 24
Scheme 5: Decomposition mechanism of protonated complexes ................................ 28
Scheme 6: Model catalytic mechanism ....................................................................... 29
Scheme 7: k2-TpPh,MeNiS,S’-dithiolene ....................................................................... 52
Scheme 8: Protonated H+-TpPh,MeNiS2CNEt2 and H+-TpPh,MeNiS2CNPh2 .................. 109
Scheme 9: Possible oxidation pathways of Ni2+ complexes ...................................... 117
Scheme 10: Idealized Ni2+/3+ redox chemistry driven by O2· radical in modeling N3S2
ligand field ............................................................................................................... 118
15
CHAPTER I: INTRODUCTION
The development of nickel dependent enzyme biochemistry has been relatively
recent.1 Urease was recognized to contain two catalytically essential nickel ions only in
1975,2 and its X-ray crystal structure was first reported in 1995.3 Eight other nickel
enzymes are known to date:
Fe/Ni-hydrogenase, carbon monoxide dehydrogenase
(CODH), acetyl-CoA synthase (ACS), methyl-coenzyme M reductase (MCR), NiSOD,
glyoxalase I, acireductone dioxygenase, and methylenediurease.1 The metalloenzyme
activities can be group into five broad classifications: hydrolases and isomerases (urease,
methylenediurease, glyoxalase I); a substrate-centered oxygenase (acireductone
dioxygenase) also featuring redox-inactive Ni2+ ions with N/O ligation; a one-electron
oxido-reductase (NiSOD) exploiting a Ni2+/3+ couple in a mixed N/S ligand field; twoelectron organometallic turnover (hydrogenase, CODH, ACS) in sulfur-dominated ligand
fields about active site clusters; and MCR, which utilizes a tetrapyrrolic macrocycle and
organosulfur cofactors. Thus, the introduction of sulfur ligands seems essential to elicit
redox biochemistry from nickel.4 Structures and properties of some of the above nickelcontaining metalloenzymes indicate that sulfur ligands play an important role in nickelcontaining enzymes.4
Superoxide dismutases (SODs) have been widely found in aerobic and anaerobic
environments.5 SODs are metalloenzymes that catalyze disproportionation of superoxide
radical to hydrogen peroxide and molecular oxygen. Mox + O2·-→ Mred + O2; and Mred +
O2·- + 2 H+ → Mox + H2O2 (where M is the metal involved in the redox reaction)5.
Through converting superoxide radical to peroxide and molecular oxygen, cells can avoid
16
oxidative stress.6-8 There are three classes of SODs: Cu/Zn-, Fe-/Mn-, and Ni-SOD.9 All
SODs employ a two-step, ping-pong mechanism. Potentials of metal ions in SODs are
tuned between the potentials for one-electron oxidation and reduction of superoxide (E0 =
-0.04 and +1.09 V vs Ag/AgCl,
10,11
respectively). SODs play an important role in
releasing the oxidative stress to cells.
NiSOD was isolated from Streptomyces and structurally characterized just a
couple of years ago and represents a new class of SOD.4,6-9,12-15 The unique active site
geometry of NiSOD consists of two thiolates (Cys2 and Cys6) and two backbone
nitrogen ligands (His1 and Cys2) that coordinate to Ni2+ to form an equatorial square
plane, and an axial His1 side chain ligand which connects to a low-spin (S = ½) Ni3+ ion
to form square pyramidal coordination environment (Figure 1). However, the metal ion is
easily photoreduced, and the X-ray crystal structures indicate the presence of a four
coordinate square planar Ni2+ geometry with a dissociated axial histidine. Reported X-ray
distances of Ni···Nax are 4.26 Å7 and 3.87 Å8. Bond lengths for Ni-Seq and Ni-Neq are
2.16(2) and 2.19(2) Å, and 1.87(6); 1.91(3) Å reported by Barondeau, D. P. B et al,7
while 2.20 and 2.22 Å, and 1.93 and 2.06 Å were found by Wuerges, J. et al8. Ligandmetal-ligand angles are near 90º.7,8
The mechanism at NiSOD active center is supposed to involve two one-electron
redox half-reactions of O2·- to form O2 and H2O2 (Scheme 1), the same as other SODs.5,1011,16
However, the details of nickel ligation and proton transfer remain controversial.
Four problems involved are: first, fast catalytic rate vs low barriers without noticeable
geometry rearrangement during catalytic cycle; second, the issue of metal-centered
17
oxidation as opposed to ligand sulfur; third, the origin and position of two required
protons; fourth, spin state change within a complete cycle. Since the axial histidine was
displaced by X-ray photoreduction of Ni3+ in the crystal structure determinations, one
proposed mechanism involves proton transfer to reduced superoxide from the histidine,
which then re-ligates to the oxidized metal, similar to Cu/ZnSOD.5,7 From the Ni3+-O2H
species, H2O2 formation occurs through a proton donation by His1 via Tyr9. A lower
exothermic energy compared to other positions on the enzyme indicates that His1 will
donate a proton.17 But another possibility is that the oxidized Ni3+ active site accepts an
electron and the terminal thiolate connected to Ni3+ is protonated during the redox
reaction, not the axial imidazole.16,18 For protonated teminal thiolate (Cys6), superoxide
binding generates a Ni3+-O2H species in a process that is exothermic by 17.4 Kcal/mol.16
Notice that the sulfur-rich ligand field at active center in NiSOD can connect to nickel in
various ways. Sulfur K-edge X-ray absorption spectroscopy (XAS) was employed to
indicate terminal thiolate bound to the Ni3+ oxidized state, and also allowed the
possibility of terminal thiol coordinated to a peroxide-reduced Ni2+ state.18 Moreover,
another mechanism proposed by hybrid density functional theory suggested that the
lowest energy catalytic pathway for NiSOD is one that involves the axial imidazole
coordination to nickel during the whole catalysis. 16 The lack of structural reorganization
in this proposal helps to explain the fast kinetic value (kobs = 2 x 109 M-1·s-1),6 but there is
no experimental evidence to support five-coordinate high-spin (S = 1) Ni2+ at the active
site. None of these proposed mechanisms for NiSOD can definitely illustrate all potential
18
problems.
Also, hydrogen-bonding interactions between first- and second-sphere
residues in the Ni enzyme appear to be crucial for maximizing catalytic turnover.6-8
A d8 Ni2+ ion occupying a square planar N2S2 ligand field will adopt a d orbital
splitting pattern with paired electrons and an empty dx2-y2 orbital, while singly occupied
dx2-y2 and dz2 orbitals can exist in a square pyramidal N3S2 ligand field due to a raised
energy level of dz2.
19
Figure 1. X-ray structures of the active site ligand field in oxidized (left) and
photoreduced (right) NiSOD (1t6u.pdb).7,8
-
+
O2 + 2H + e
- +0.87V
Ni(II)
O2
Eo
+0.29V
-0.16V
2O2 + 2H+
H2O2
Ni(III) + eO2 + eO2 + H2O2
V vs NHE
Scheme 1. Disproportion mechanism in NiSOD.
20
Meanwhile, stabilization of the dz2 orbital in a trigonal bipyramidal N3S2 ligand
set induces single electron occupancy of dx2-y2 and dxy (Scheme 2). Calculations
demonstrate that the oxidative site is nickel but not sulfur, 19 and other studies indicate
that the axial imidazole plays a vitally important role in optimizing the rate of O2· disproportionation.9,20 Investigation of the role of the axial imidazole indicated that its
ligation reduces the overall structural rearrangement taking place at the Ni-center, which
probably can increase the rate of the Ni-centered redox processes and also lower the
Ni2+/3+ redox potential of the five-coordinate Ni2+ center compared to four-coordinate
Ni2+ center, which is helpful to explain how the midpoint of the O2·- oxidation and
reduction potential can be reached in NiSOD active site.9,16 Although many efforts have
been made to unlock the catalytic process in NiSOD, from spectroscopic to
computational methods, models to mimic the active center are still being designed and
examined. Notice that axial nitrogen donor plays an important role during the catalytic
process and sulfur-rich coordination environment probably can stabilize Ni3+ and
decrease the potential of Ni2+/3+ redox couple. Models containing potential tuning of
nitrogen donor and sulfur-rich ligands are possible to mimic the whole cycle.
Various synthetic models for the NiSOD active site have been reported by
others.19,21-31 (Scheme 3) The first NiN2S2 complex supported by mixed amine/amide
donors displayed Ni-S bonds at 2.18 and 2.14 Å and Ni-N bonds at 1.99 and 1.86 Å,
which compare well with the metalloenzyme.21 Though a quasi-reversible Ni2+/3+ redox
couple was observed, suggesting that NiSOD utilizes the mixed amine/amide ligands to
21
modulate the Ni2+/3+ redox couple,32 it lacks the potential and crucial axial donor to
modulate the reduced square planar geometry to the oxidized square pyramidal geometry.
22
dx2-y2
dx2-y2
dx2-y2 ,dxy
dxy
dx2-y2
dz2
dxy
dz2
dxy
d z2
dxz,yz
dxz,yz
dxz,yz
l-s Square planar vs h-s Square pyramidal
dz2
dxz,yz
l-s Square planar vs h-s Trigonal bipyramidal
Scheme 2. Ligand field splitting for d8 Ni2+.
21-
Ph
S
N
O
Ni
N
O
N
O
Ni
S
S
N
N
N
Ni
S
S
S
Scheme 3. Representive synthetic model Ni2+N2S2 complexes.21,33-34
O
23
This work will focus on modeling the structure and mechanism of NiSOD by
small-molecule complexes. Studies about metabolic bio-organometallic reactivity by
nickel-containing metalloenzymes indicated important valence change during this kind of
reactivity.1 So, questions related to valence, geometry and spin change should be solved
in order to explain how they affect reactivity at model nickel centers. Inspired by the
unique (N3S2)3- active site ligand field, our work employed N3-tripod and S,S’-chelating
ligands to stabilize different nickel states to try to explain relationships among variant
states. Hydro(trispyrazoyl)borate ligands were prepared to be a N3-tripod ligand. S,S′chelating organoxanthate (xan) and dithiocarbamate (dtc) were utilized to mimic the
dithiolate motif (Scheme 4). These above ligands could form 4- and 5-coordinate Ni2+
complexes due to “scorpionate” equilibrium between k2-Tp and k3-Tp binding modes,35
which can provide samples to study the reduced state in NiSOD. Our results
demonstrated an axial base equilibrium in our model Ni2+ complexes, show how steric
effects can affect this behavior,36-38 and demonstrated protonation and quasi-reversible
oxidation.
24
H
O
O
EtOH
R
KBH4
N
N
NH2NH2
R
R= Me, Ph
ERn
Cl
R
R
K
N
N
N
N
N N
B
H
R
R
TlHC(O)O
NiCl2
Ni
N
N
N
S
R
N
N N
B
H
R
R
N
- NaX
CH2Cl2
N
Scheme 4. Synthesis of N3S2Ni2+ model complexes.
R
Ni R
+ NaS2CERn'
ERn' = OMe, OEt
NEt2, NPh2
S
N
N
N N
B
H
25
Equilibration of 4- and 5-coordinate structures. The geometry in NiSOD may
change during the redox process from reduced 4-coordinate square planar to oxidized 5coordinate square pyramidal. Therefore, it is important to study the geometry changes.
The 4-coordinate square planar Ni2+ center in NiSODred could bind the axial imidazole
once it is deprotonated, which could be removed by O2· - to form a 5-coordinate oxidized
square pyramidal state. 1H NMR spectra revealed that our model complexes are
paramagnetic in solution. In contrast, diamagnetic Ni2+ square planar complexes are
observed at solid state. FT-IR spectra of the solid state (KBr pellets) confirmed the k2tris(pyrazolyl)borate binding leading to the 4-coordinate environment at Ni2+ center
determined by X-ray single crystal diffraction.39,40 Solution FT-IR (in CH2Cl2) and nujol
gave evidence for k3-binding and a 5-coordinate Ni2+ environment, indicating the
existence of coordination number change (coordination equilibrium) in liquid state.
Variable temperature and titration UV-Vis-NIR data also confirmed these two isomers.36
Through controlling steric effects and temperature we obtained solid state isomers. X-ray
single crystal diffracton confirmed both 4/5-coordinated isomers,38 which is rare since
only a couple of examples were reported.41-44 We observed spin change even in solid
state and SQUID data supported spin crossover with change in temperature.38 A novel
spin crossover behavior mediated by axial distortion in our modeling complexes shed
light on illustrating mechanism in NiSOD.
Interaction of protons with divalent complexes. During the redox process in
NiSOD, two protons are required. One proton is supposed to come from protonated axial
His1 or a Cys6 thiol, and the other comes from other residues. So, we treated Ni2+
26
complexes with weak acid trifluoacetic acid to investigate the possible protonation
positions in our synthetic models. As expected, the axial nitrogen donor was protonated
first, but it was also removed and substituted by anion group CF3COO- to give a
Ni2+N2S2(OOCCF3) complex, which was unexpected. And more interestingly, the
trifluoacetic acid can also protonate the dithioacid, too.38 The axial nitrogen was
protonated first then the proton migrates to equatorial sulfur atom to drag away dtc
ligand. Then the free pyrazole and anion group CF3COO- bind nickel to obtain
Ni2+N3(OOCCF3)(pz) complex (Scheme 5).
Oxidation to Ni3+. Binding the axial His1 imidazole ligand and switching from
square planar to square pyramidal geometry would increase ligand field stabilization, thus
favoring Ni3+ and lowering the midpoint potential of Ni3+/2+ couple into the range suitable
for superoxide dismutation. Electrochemistry data indicated that Ni2+ complexes are
suitable to be oxidized. For example, E½ = 0.35 V for TpPh,MeNiS2CNEt2 and E½ = 0.48 V
for TpPh,MeNiS2CNPh2 vs. Ag/AgCl in CH2Cl2. These half-potentials both fall in the range
suitable for SODs activity, though a potential problem is that the observed oxidations
may involve the supporting dithiocarbamate ligands rather than occurring cleanly at the
metal center. We also prepared Co2+N3S2, as the isoelectronic analogues of Ni3+N3S2;
Co2+, is a d7 ion equal to Ni3+. A series of Co2+ complexes ligated by corresponding
hydro(trispyrazoyl)borate
ligands
and
S,S′-chelating
organoxanthate
(xan)
or
dithiocarbamate (dtc) were synthesized and characterized.38
Based largely on these data, we proposed a model catalytic mechanism (Scheme
6), which might be also true in real NiSOD enzyme. This is the third, novel protonation
27
mechanism which involves both axial and equatorial donors. The advantages of this
mechanism are as followings: first, it can solve the issue of avoiding sulfur oxidation
during the process from Ni2+ to Ni3+; second, the proton migration from axial N to
equatorial S can shorten the distance between the nickel bonding group HOO- and H+ to
solve the issue of long distance to remove axial proton on nitrogen to obtain H2O2 ; third,
it can combine the axial nitrogen donor in the redox reactions, which is quite important
for tuning potentials to mild conditions.
28
R
O
NH N
R
CF3C O
R
R
R
Ni
N
N
R
N N
B
H
NR'2
C
S OOCCF
3
NH
N N
N
C
HS
R
Ni
CF3COO-
NR'2
+
HS
R
R
NH
S
N
R
R
Ni
N
N N
N
N N
N
N N
B
N
N N
B
H
H
CF3COOH
HSSCNR'2
CF3COO-
NR'2
C
S S
R
Ni
R
NR'2
R
C
S S
N N
N N N
B
NH+
NR'2
K
OH
CO
F
3
C
t
NE 3
C
S
R
S
Ni
N
N
N
R
CF
3C
H
Ni
O
O-
R
NH+
R
N
R
N N
N N
B
H
N
N N
B
NR'2
CF
3 CO
OH
C
S S
H
R=R'=Ph
R
Ni
O
R
R
N N
CF3C O N N
B
H
R
N
NH
Scheme 5. Decomposition mechanism of protonated complexes.
R
29
NR'2
NR'2
C
S S
3+ R
Ni
R
N
N
NR'2
C
S S O-O
3+ R
R
Ni
R
N
N N
N
N N
B
-O
O
N
N
H2O2
N
N
N N
B
k =? kobs = 2 x 109 M-1 s-1 in NiSOD
NR'2
NR'2
NR'2
C
C
C
S S
2+ R
Ni
N
N
H
H
R
O2
N
N
N N
B
O-O
H
R
R
C
H+
S S O-OH
3+ R
R
Ni
N N
N N
B
H
S S
2+ R
Ni
R
R
+
H+
NH
N
R
N N
N N
B
H
R=R'=Ph
Scheme 6. Model catalytic mechanism.
S S O-OH
3+ R
R
Ni
R
HO-O
+
NH N N
N
N N
B
H
30
CHAPTER II: EXPERIMENTAL SECTION
Materials.
The complexes, TpMe,MeNiCl and TpPh,MeNiCl were prepared by modified
literature procedure.45 TpPh,MeCoCl was prepared by the same procedure as TpPh,MeNiCl
using anhydrous CoCl2 instead of anhydrous NiCl2. Carbon disulfide, methanol, ethanol,
dimethyl amine, diethyl amine, diphenyl amine and sodium hydroxide were purchased
from Aldrich without further purification. Sodium amide was purchased from Aldrich
and stored and handled at air free conditions. Tetrabutylammonium hexafluorophophate
(TBAPF6) was purchased from Fluka and recrystallized from hot ethanol three times.
Trifluoacetic acid (CF3COOH) was purchased from Thermo Fisher Scientific. Standard
Schlenk-line and glove-box techniques were employed to handle air/moisture sensitive
materials. Dichloromethane (DCM), dichloroethane (DCE), toluene, acetonitrile (ACN),
and methanol were degassed and distilled over anhydrous calcium hydride (CaH2) before
use. Tetrahydrofuran (THF) and diethyl ether (Et2O) were degassed and distilled over
calcium hydride then over sodium/benzophenone (Na/Ph2CO). Chloroform-d (CDCl3)
was dried over molecular sieves overnight and then dried over anhydrous CaH2 overnight
and afterwards transferred to another Schlenk flask and freeze/thaw degassed by liquid
nitrogen three times before use. The same procedure was used to process methylene
chloride-d2 (CD2Cl2), toluene-d8 and acetonitrile-d3 (CD3CN). Thermodynamic
equilibrium experiments were carried out in an airfree sealed cuvette, with temperature
controlled by a regulated circulation bath and calibrated by a 100ºC thermometer before
31
use. Stock solutions were prepared by mixing trifluoroacetic acid and triethylamine into
dry DCM to make acid and base titration solutions to do the titration.
32
Synthesis of sodium dithioacid salts. To neat methanol (15 mL, 250 mmol) was
added 1.0g (25 mmol) sodium hydroxide dissolved in a minimum amount of water. The
solution was cooled in an ice water bath (0 ºC), and carbon disulfide (15 mL, 250 mmol)
was added dropwise.
The bath was removed after stirring 0.5 h and stirring was
continued for 1.5 h., during which the color of the solution changed to light-yellow.
Solvent was removed under vacuum to give sodium O-methylxanthate as a pale yellow
semicrystalline solid. Yield: 2.96 g (80%). This procedure was repeated using ethanol
(84% yield) or dimethylamine (59% yield) or diethylamine (1:1 vs. NaOH, 93% yield) in
place of methanol.
Synthesis of sodium N,N-diphenyldithiocarbamate, alternate procedure. To solid
diphenylamine (1.00 g, 5.90 mmol) and sodium amide (0.23 g, 5.90 mmol) was added
distilled toluene (20 mL) under a nitrogen purge. After stirring for 10 min at room
temperature, carbon disulfide (15 mL, 250 mmol) was added dropwise. The resulting
yellow suspension was evaporated to dryness to give the product salt as a yellow solid.
Yield: 1.55 g (98%).
Synthesis of TpMe,MeNiS2COMe (1). To a solution of TpMe,MeNiCl (100 mg, 0.26
mmol) in CH2Cl2 (20 mL) was added solid sodium O-methylxanthate (51 mg, 0.39
mmol). The color of the solution changed from pale pink to green. The mixture was
stirred 4 h and then filtered. Solvent was removed under vacuum to yield a green
powder. Crystalline material was obtained by slow evaporation of a CH3CN solution.
Yield: 80 mg (67%). Anal. calc’d. (found) for C17H25BN6NiOS2: C, 44.09 (44.08); H,
5.44 (5.42); N, 18.15 (18.39). 1H NMR (CDCl3, 295 K; δ, ppm): 67.4 (3H, 4-pz); 27.1
33
(3H, OMe); 1.5 (9H, 5-Me); -7.9 (9H, 3-Me); -9.2 (1H, B-H); µ eff = 2.67µ B. UV-Vis
(CH2Cl2, λmax, nm; ε, mM-1 cm-1): 230 (14.4), 260 (6.6), 292 (8.5), 415 (0.6), 655 (0.1).
IR (KBr, cm-1): 2521, ν (B-H); 1228, ν (C-O-C); 1171, ν (C-O); 1053, ν(C=S).
Synthesis of TpMe,MeNiS2COEt (2). The synthesis was carried out by the same
method as 1 above using TpMe,MeNiCl (100 mg, 0.26 mmol) and O-ethylxanthate (56 mg,
0.39 mmol). Yield: 76 mg (61%). Anal. Calc’d. (found) for C18H27BN6NiOS2: C, 45.32
(45.32); H, 5.70 (5.70); N, 17.61 (17.87). 1H NMR (CDCl3, 295 K; δ, ppm): 67.1 (3H,
4-pz); 13.4 (2H, OCH2); 3.2 (3H, OCH2CH3); 1.4 (9H, 5-Me); -7.9 (9H, 3-Me); -9.3 (1H,
B-H); µ eff = 2.71 µ B. UV-Vis (CH2Cl2, λmax, nm; ε, mM-1 cm-1): 231 (18.4), 261 (9.4),
292 (11.5), 415 (0.7), 662 (0.1). IR (KBr, cm-1): 2514, ν (B-H); 1222, ν (C-O-C); 1124,
ν (C-O); 1040, ν (C=S).
Synthesis of TpMe,MeNiS2CNEt2 (3). The synthesis was carried out by the same
method as 1 above using TpMe,MeNiCl (100 mg, 0.26 mmol) and NaS2CNEt2 (67 mg, 0.39
mmol). Yield: 78 mg (60%). Anal. Calc’d. (found) for C20H32BN7NiS2: C, 47.65
(47.55); H, 6.40 (6.53); N, 19.45 (19.51). 1H NMR (CDCl3, 295 K; δ, ppm): 63.1 (3H,
4-pz); 36.6 (4H, N-CH2); 2.6 (6H, NCH2CH3); 0.3 (9H, 5-Me); -7.7 (9H, 3-Me); -9.8 (1H,
B-H); µ eff = 2.75 µ B. UV-Vis (CH2Cl2, λmax, nm; ε, mM-1cm-1): 230 (17.9), 278 (15.2),
420 (0.8), 644 (0.1). IR (KBr, cm-1): 2520, ν (B-H); 1497, ν (C=NR2); 998, ν (C=S).
Synthesis of TpMe,MeNiS2CNPh2 (4). The synthesis was carried out by the same
method as 1 above using TpMe,MeNiCl (100 mg, 0.26 mmol) and NaS2CNPh2 (104 mg,
0.39 mmol). Yield: 112 mg (72%). Anal. Calc’d. (found) for C28H32BN7NiS2: C, 56.03
(55.83); H, 5.37 (5.47); N, 16.33 (16.83). 1H NMR (CDCl3, 295 K; δ, ppm): 63.6 (3H,
34
4-pz); 9.4 (4H, N-Ph, ortho); 7.7 (4H, N-Ph, meta); 4.3 (2H, N-Ph, para); 0.6 (9H, 5-Me);
-7.7 (9H, 3-Me); -9.5 (1H, B-H); µ eff = 2.76 µ B. UV-Vis (CH2Cl2, λmax, nm; ε, mM-1 cm1
): 230 (25.6), 292 (20.6), 426 (1.2), 651 (0.1). IR (KBr, cm-1 ): 2520, ν (B-H); 1592, ν
(C=C); 1497, ν (C=NR2).
Synthesis of TpPh,MeNiS2CNEt2 – Red (5). The synthesis was carried out by the
same method as 1 for overnight stirring instead of 4h above using TpPh,MeNiCl (100 mg,
0.17 mmol) and NaS2CNEt2 (45 mg, 0.26 mmol). Yield: 64mg, 55%. Anal. Calc’d.
(found) for C35H38BN7NiS2: C, 60.89 (60.84); H, 5.55 (5.55); N, 14.20 (14.26). 1H NMR
(CDCl3, 295 K; δ, ppm): 52.7 (3H, 4-H); 34.0 (4H, N-CH2); 7.1 (3H, 3-Ph, para); 6.8
(6H, 3-Ph, meta); 4.7 (6H, 3-Ph, ortho); 1.6 (9H, 5-Me); 1.1(6H, NCH2CH3); -8.5 (1H, BH). µ eff = 2.52 µ B. UV-Vis (CH2Cl2, λmax, nm; ε, mM-1 cm-1): 240 (60.3), 323 (17.6), 380
(sh, 3.0), 397 (sh, 2.6), 420 (1.5), 642 (0.1). IR (KBr, cm-1 ): 2531, ν (B-H); 2478, ν (BH)sh; 1511, ν (C=NR2); 1276, ν (C-N).
Synthesis of TpPh,MeNiS2CNEt2 – Green (6). The synthesis was carried out by the
same method as 5. Green crystals were obtained at room temperature under the same
condition in 5 but was kept cold by dry ice during delivery to characterize at 173 K.
Synthesis of TpPh,MeNiS2CNPh2 – Red (7). The synthesis was carried out by the
same method as 5 above using TpPh,MeNiCl (100 mg, 0.17 mmol) and NaS2CNPh2 (70
mg, 0.26 mmol). Yield: 104 mg, 78%. Anal. Calc’d. (found) for C43H38BN7NiS2: C,
65.67 (65.73); H, 4.87 (4.81); N, 12.47 (12.49). 1H NMR (CDCl3, 295 K; δ, ppm): 54.4
(3H, 4-H); 8.6 (4H, N-Ph, ortho); 7.8 (4H, N-Ph, meta); 7.4 (3H, 3-Ph, para); 6.9 (6H, 3Ph, meta); 4.5 (3H, 3-Ph, ortho); 4.2 (2H, N-Ph, para); 2.1 (9H, 5-Me); -8.3 (1H, B-H).
35
µ eff = 2.49 µ B. UV-Vis (CH2Cl2, λmax, nm; ε, mM-1 cm-1): 241 (55.8), 297 (18.0), 428
(1.6), 655 (0.1). IR (KBr, cm-1 ): 2548, ν (B-H); 2468, ν (B-H)sh; 1489, ν (C=NR2); 1305,
ν (C-N). IR (Nujol, cm-1 ): 2456, ν (B-H).
Synthesis of TpPh,MeNiS2CNPh2 – Green (8). The synthesis was carried out by the
same method as 7. Green crystals were obtained at -33ºC by DCM/n-hexane diffusion
and characterized at 173 K. IR (Nujol, cm-1 ): 2547, ν (B-H).
Synthesis of TpPh,MeNiS2COEt (9). The synthesis was carried out by the same
method as 5 above using TpPh,MeNiCl (100 mg, 0.17 mmol) and NaS2COEt (37 mg, 0.26
mmol) . Yield: 90 mg, 80%. Anal. Calc’d. (found) for C33H33BN6NiOS2: C, 59.75
(59.79); H, 5.01 (5.09); N, 12.67 (12.75). 1H NMR (CDCl3, 295 K; δ, ppm): 63.2 (3H, 4H); 22.3 (2H, OCH2); 7.0 (3H, 3-Ph, para); 6.9 (6H, 3-Ph, meta); 4.0 (6H, 3-Ph, ortho);
3.5 (3H, OCH2CH3); 2.4 (9H, 5-Me); -9.5 (1H, B-H). µ eff = 2.71 µ B. UV-Vis (CH2Cl2,
λmax, nm; ε, mM-1 cm-1): 236 (55.7), 289 (12.4), 361 (1.0), 431 (1.3), 670 (0.1). IR (KBr,
cm-1 ): 2541, ν (B-H); 1220, νas (C-O-C); 1124, νs (C-O-C); 1045, ν (C=S).
Synthesis of TpPh,MeNiS2CNMe2 –LT (10,11). The synthesis was carried out by the
same method as 5 above using TpPh,MeNiCl (450 mg, 0.78 mmol) and NaS2CNMe2 (168
mg, 1.17 mmol) . Yield: 294 mg, 57%. Allogons of green crystals were obtained at room
temperature but then cooled down by dry ice. X-ray single crystal diffraction was
characterized at low temperature to obtain two different crystal structures in one unit cell.
Anal. Calc’d. (found) for C33H34BN7NiS2: C, 59.84 (59.91); H, 5.17 (5.24); N, 14.80
(14.78); S, 9.68 (10.09). 1H NMR (CDCl3, 295 K; δ, ppm): 53.5 (3H, 4-H); 43.3 (6H, NCH3); 6.8 (9H, 3-Ph, para and meta); 4.6 (6H, 3-Ph, ortho); 1.8 (9H, 5-Me); -8.3 (1H, B-
36
H). µ eff = 2.77 µ B. UV-Vis (CH2Cl2, λmax, nm; ε, mM-1 cm-1): 239 (48.8), 300 (8.5), 360
(1.3), 426 (0.7), 649 (0.02). IR (KBr, cm-1 ): 2529, ν (B-H); 2474, ν (B-H)sh; 1474, ν
(C=NR2); 1256, ν (C-N); 985, ν (C=S). IR(Nujol, cm-1 ): 2524, ν (B-H).
Synthesis of TpPh,MeNiS2CNMe2 –RT (12). The synthesis was carried out by the
same method as 10,11. Green crystals were obtained and characterized at room
temperature.
Synthesis
of
(CF3COO)BpPh,MeNiS2CNPh2
(13).
To
the
complex
7
TpPh,MeNiS2CNPh2 (36 mg, 0.046 mmol) dichloromethane green solution was added 1
equivelent trifluoacetic acid, color changed from green to red immediately. n-Hexane was
layered on top to obtain red crystalline solid. Yield: 23 mg. Anal. Calc’d. (found) for
C35H29BF3N5NiO2S2:
C, 56.63 (56.18); H, 3.94 (4.17); N, 9.43 (10.42). 1H NMR
(CDCl3, 295 K; δ, ppm): 7.4, 7.3 (20H, 3-Ph, N-Ph); 6.9 (2H, 4-H); 2.3 (6H, 5-Me). UVVis (CH2Cl2, λmax, nm; ε, mM-1 cm-1): 240 (25.2), 296 (9.2), 365 (1.7), 424 (0.4). IR
(KBr, cm-1 ): 2510, ν (B-H); 1674, ν (C=O); 1488, ν (C=NR2); 1310, ν (C-N); 1128, ν
(C-F). IR (Nujol, cm-1 ): 2507, ν (B-H).
Synthesis of TpPh,MeNi(pz)(OOCCF3) (14). The synthesis was carried out by the
similar method as 13 but using excess trifluoacetic acid. Anal. Calc’d. (found) for
C42H38BN8F3NiO2: C, 62.02 (61.62); H, 4.71 (4.61); N, 13.78 (13.77). 1H NMR (CDCl3,
295 K; δ, ppm): 66.5 (1H, N-H); 63.1 (3H, 4-H); 47.3 (1H, 3-pz-H); 11.0 (3H, 5-pz-Me);
9.2 (6H, 3-Ph, ortho); 8.7 (3H, 3-Ph, para); 8.2 (6H, 3-Ph, meta); 6.7 (3H, 3-pz-ph, meta
and para); 5.4 (2H, 3-pz-ph, ortho); 2.6 (9H, 5-Me); -10.2 (1H, B-H). UV-Vis (CH2Cl2,
37
λmax, nm; ε, mM-1 cm-1): 243 (35.1), 324 (0.9), 382 (0.2), 430 (0.1), 641 (0.04). IR (KBr,
cm-1 ): 2544, ν (B-H); 1666, ν (C=O); 1138, ν (C-F).
Synthesis of TpPh,MeCoS2CNEt2 (15). The synthesis was carried out by the same
method as 5 above using TpPh,MeCoCl (150 mg, 0.26 mmol) and NaS2CNEt2 (68 mg, 0.40
mmol). Yield: 92 mg, 51%. Anal. Calc’d. (found) for C35H38BN7CoS2: C, 60.87 (60.48);
H, 5.55 (5.63); N, 14.20 (14.45). 1H NMR (CDCl3, 295 K; δ, ppm): 113.8 (1H, B-H);
97.4 (3H, 4-H); 50.6 (9H, 5-Me); 47.6 (4H, N-CH2); 30.8 (6H, NCH2CH3); 5.3 (3H, 3-Ph,
para); 3.6 (6H, 3-Ph, meta); -71.1 (6H, 3-Ph, ortho); µ eff = 4.12 µ B. UV-Vis (CH2Cl2,
λmax, nm; ε, mM-1 cm-1): 242 (49.9), 401 (0.8), 636 (0.1) . IR (KBr, cm-1 ): 2536, ν (BH); 1497, ν(C=NR2); 1275, ν (C-N).
Synthesis of TpPh,MeCoS2CNPh2 (16). The synthesis was carried out by the same
method as 5 above using TpPh,MeCoCl (150 mg, 0.26 mmol) and NaS2CNPh2 (104 mg,
0.39 mmol) Yield: 50 mg, 24%. Anal. Calc’d. (found) for C43H38BN7CoS2: C, 65.67
(65.85); H, 4.87 (4.97); N, 12.47 (12.87). 1H NMR (CDCl3, 295 K; δ, ppm): 103.9 (1H,
B-H); 49.2 (3H, 4-H); 48.7 (9H, 5-Me); 37.1(4H, N-Ph, ortho); 20.2 (4H, N-Ph, meta);
11.7 (2H, N-Ph, para); 4.5 (6H, 3-Ph, meta); 2.2 (3H, 3-Ph, para); -64.7(6H, 3-Ph,
ortho). µ eff = 4.20 µ B. UV-Vis (CH2Cl2, λmax, nm; ε, mM-1 cm-1): 239 (36.1), 288 (14.3),
401 (0.7). IR (KBr, cm-1): 2549, ν (B-H); 1488, ν (C=NR2), 1303, ν (C-N).
Synthesis of TpPh,MeCoS2COEt (17). The synthesis was carried out by the same
method as 5 above using TpPh,MeCoCl (150 mg, 0.26 mmol) and NaS2COEt (56 mg, 0.39
mmol). Yield: 170 mg, 99%. Anal. Calc’d. (found) for C33H33BN6CoOS2: C, 59.73
(59.62); H, 5.01 (5.07); N, 12.67 (12.64). 1H NMR (CDCl3, 295 K; δ, ppm): 81.9 (1H, B-
38
H); 53.1(3H, 4-H); 43.3 (9H, 5-Me); 26.5 (2H, OCH2); 10.3 (3H, OCH2CH3); 6.8 (6H, 3Ph, meta); 5.0 (3H, 3-Ph, para); -47.8 (6H, 3-Ph, ortho). µ eff = 4.31µ B. UV-Vis (CH2Cl2,
λmax, nm; ε, mM-1 cm-1): 238 (47.2), 343 (2.9), 391 (0.8). IR (KBr, cm-1 ): 2545, ν (B-H);
1216, ν (C-O-C)as; 1124, ν (C-O-C)s; 1045, ν (C=S).
Synthesis of TpPh,MeNi(THF)(CH3CN) (18). Silver tetrafluoroborate (27 mg, 0.14
mmol) was added to complex 5 TpPh,MeNiS2CNEt2 (50 mg, 0.07 mmol) dissolved in
minimum distilled acetonitrile solution. Stirring for 10 min at room temperature in
glovebox then was kept at -33ºC for a couple of days. The clear dark green solution was
filtered, and solids were obtained by stripping off solvent. The solid was then dissolved in
minimum dry THF and layered on dry Et2O to obtain X-ray quality crystals at -33ºC.
39
Instrumentation.
1
H NMR Spectroscopy. All paramagnetic proton nuclear magnetic resonance
spectra were recorded on a 500 MHz Varian spectrometer INOVA-500 in chloroform-d
(CDCl3), methylene chloride-d2 (CD2Cl2), toluene-d8 or acetonitrile-d3 (CD3CN).
Diamagnetic proton nuclear magnetic resonance spectra were collected on a 300 MHz
Bruker AG spectrometer in the same solvents.
Magnetic susceptibility. Solid-state magnetic susceptibility measurements on 1
and 12 were performed on a 7 T Quantum Design MPMS SQUID magnetometer by Mr.
Guangbin Wang and/or Prof. Gordon T. Yee of Virginia Tech. Measurements of
magnetization as a function of temperature were performed from 5 to 300 K and in a
5000 G field. Samples of TpMe,MeNiS2COMe and TpPh,MeNiS2CNMe2 were prepared as a
fine powder. The sample was packed between cotton plugs, placed into gelatin capsules,
cooled in zero applied field, and measured upon warming. Diamagnetic corrections were
applied on the basis of Pascal’s constants. The data were corrected for the diamagnetism
of the gel cap and the cotton plug. Solution measurements were made by the Evans
NMR method.46 Norell coaxial inserts for 5 mm NMR Tube were purchased from
Chemglass. The outer NMR tube can be purchased elsewhere. Evans NMR spectra were
recorded on either 500 MHz or 300 MHz spectrometers described above.
EPR Spectroscopy. Electron paramagnetic resonance (EPR) spectra were
collected at University of Minnesota by Dr. Aidan MacDonald and Prof. Lawrence Que,
Jr. Samples of complexes 15 TpPh,MeCoS2CNEt2, 16 TpPh,MeCoS2CNPh2 and 17
40
TpPh,MeCoS2COEt were prepared as crystals. Temperature dependent EPR spectra were
collected between 2.4 and 30 K.
Electrochemistry. Cyclic voltammetry was performed using a CH Instruments
CH1730A workstation. Data were recorded at room temperature in CH2Cl2 with 0.1 M
Bu4NPF6 supporting electrolyte using platinum working and counter electrodes and a
Ag/AgCl reference electrode, at scan speeds of 50-200 mV/s.
Quasi-reversible one
electron processes were observed for all complexes except complexes 14 and 18.
UV-vis Spectroscopy. UV-vis spectra were measured on an Agilent 8453 UVvisible Spectroscopy System. General purpose Agilent ChemStation software for UVvisible spectroscopy running on a PC to process the obtained spectra. Heating and
cooling was controlled by a VWR bath.
FT-IR Spectroscopy. NICOLET 380 FT-IR by thermo electron corporation.
OMNIC spectroscopy software package. FT-IR Grade KBr was used from Alfa Aesar.
Nujol from PIKE Technologies Spectroscopic Creativity.
X-ray crystallography. The structure of complex 1 was determined by Prof.
Michael P. Jensen at the 2007 Summer Crystallography School at the University of
California San Diego Small Molecule Crystallography Facility, directed by Professor
Arnold L. Rheingold. Data collection and structure solution of complexes 6, 8, 10, 11 and
18 were conducted by Dr. Victor G. Young, Jr at University of Minnesota. The remaining
structures were determined by Prof. Jeffrey L. Petersen at West Virginia University.
41
CHAPTER III: SCORPIONATE TpPh,Me LIGAND EQUILIBRIA FOR
MODELING REDUCED NiSOD INTERMEDIATES
Organisms inhabiting aerobic environments have evolved multiple layers of
defense against oxidative stress caused by partial reduction of dioxygen.47 Prominent
among these are superoxide dismutases (SODs).5
These enzymes are particularly
interesting from a mechanistic perspective. While any metal ion exhibiting a fast oneelectron couple poised between the redox half-reactions of superoxide can in principle
catalyze its disproportionation (Scheme 1), low metal concentrations in the biological
milieu necessitate tight binding of metal ions by SODs and control of redox reactivity
without introducing kinetic barriers that would obviate fast reactivity with the O2•- flux.
In a striking example of convergent evolution,7,8,48 nature has obtained disparate active
sites to carry out this reaction, utilizing Cu1+/2+, Mn2+/3+, Fe2+/3+ or Ni2+/3+ couples.
Understanding how the distinct active site structures and dynamics lead to common SOD
activity thus gains significance.
X-ray structures of NiSOD were recently reported (Figure 1).7,8 The active site
supports an unusual Ni3+ ion in a square-pyramidal N3S23- ligand field comprised of the
N-terminal amine, an axial 1-histidine imidazole, an adjacent backbone amide, and 2- and
6-cysteine thiolates (Figure 1, left). EPR spectra are also consistent with low-spin (S =
½) Ni3+ and an axial nitrogen donor.6,20 Photoreduction of this resting state by X-rays
prompts axial imidazole dissociation, generating a classical square-planar Ni2+ center
(Figure 1, right). The freed imidazole rotates toward flanking backbone carbonyls,
suggestive of protonation.7,8 Thus, the reductive half-reaction to H2O2 may be driven by
42
proton transfer from His-1 and re-coordination to Ni3+,20 analogous to the mechanistic
role of the bridging imidazole in Cu/Zn-SOD.49 However, superoxide approaches the
active site from the opposite face of the N2S2 equatorial plane, precluding direct proton
transfer to nascent peroxide.7 Sulfur K-edge XAS studies indicate ligation of equatorial
thiolates in photoreduced enzyme, but protonated thiols in peroxide-reduced samples.18
A DFT study alternatively proposed five-coordinate, high-spin (S = 1) Ni2+ as a reduced
catalytic intermediate, with transient protonation of the Cys-2 thiolate adjacent to an
inner-sphere peroxide; this gives a calculated turnover barrier of only 12 kcal/mole.16
Others favor outer-sphere turnover with only weak axial imidazole binding at
diamagnetic Ni2+.9 A significant mechanistic role for the axial His-1 base is indicated by
loss of activity in an H1Q mutant;6 manipulation of the axial bond may constitute a
mechanism for redox tuning of NiSOD.4,9,16
Intrigued by the interplay of geometry, spin state, protonation and redox reactivity
at this unique active site, and the consequent mechanistic uncertainties in NiSOD
turnover, we modeled salient features of the ligand field into synthetic complexes. We
utilized the hydrotris(3-phenyl,5-methylpyrazolyl)borate ligand (i.e., TpPh,Me) to mimic
the monoanionic facial array of nitrogen donors;50 such “scorpionate” ligands can adopt
variable k2- and k3-chelate modes on diamagnetic 4d8 and 5d8 metal ions [e.g., Rh1+, Ir1+,
Pt2+], albeit without spin crossover.40 1,1-S,S'-chelating dithiocarbamates (R2NCS2-, R =
Et, Ph)51 and organoxanthate (EtOCS2-)52 were used as co-ligands to mimic the dithiolate
motif; their zwitterionic resonance forms afford k2-chelation of anionic sulfurs while
43
maintaining charge neutrality at Ni2+. These co-ligands also provide a range of sterics
(i.e., NPh2 > NEt2 > OEt) and donor strength (i.e., NEt2 > NPh2 > OEt).
Complexes were prepared by metatheses of S,S'-chelate sodium salts with
TpPh,MeNiCl.53
The complexes exhibited ν(B-H) modes at 2545 cm-1 in solution,
indicating k3-TpPh,Me ligation,40 as well as UV-visible spectra consistent with fivecoordinate, high-spin Ni2+.53,54 Absorption bands near 425 nm (ε = 1.3-1.6 mM-1 cm-1)
and 655 nm (ε = 0.1 mM-1 cm-1) weakly blue-shifted with increasing S,S'-chelate donor
strength, consistent with ligand field character, while a near-UV band (ε = 13-17 mM-1
cm-1) strongly red-shifted, consistent with LMCT character. (Figure 2, Table 1) The
complexes yielded 1H NMR spectra with paramagnetic shifting of resonances that were
nonetheless consistent with the formulations. (Figure 3, Table 2)
For example, the
spectrum of TpPh,MeNS2CNEt2 in CDCl3 at 295 K contained scorpionate ligand
resonances due to 5-Me substituents at 1.6 ppm, the 3-Ph groups at 7.1 (para), 6.8 (meta)
and 4.7 (ortho), the 4-pyrazolyl ring protons at 52.7 ppm, and the borohydride at -8.5
ppm; the N-ethyl signals were found at 34.0 (CH2) and 1.1 ppm (CH3). Analogous results
were obtained for TpPh,MeNS2COEt and TpPh,MeNS2CNEt2, although the 4-pyrazolyl ring
proton paramagnetic shifts varied noticeably, falling at 63.2 ppm and 54.4 ppm,
respectively.
Equivalent resonances indicated k3-TpPh,Me coordination and rapid site
exchange in all complexes.
Meanwhile, solvent dependent
1
H NMR for
TpPh,MeNiS2CNEt2 (Figure 4) and variable temperature 1HNMR for TpPh,MeNiS2CNPh2
(Figure 5) were recorded to support coordination change in our model complexes. Also,
one more electron rich compound TpPh,MeNiS2-S,S’-C6H4 was prepared and characterized
44
by 1H NMR (Figure 6, Scheme 7 and Table 3); a diamagnetic 1H NMR spectrum was
observed, consistent with dissociated pyrazole arm, and further supporting a role for
equatorial ligand donor strength in addition to steric effects in modulating the axial
equilbrium.
Despite common solution spectra, divergent solid-state structures were obtained.
Red crystals of the dithiocarbamate complexes exhibited ν(B-H) modes at 2480 cm-1 in
KBr pellets, indicative of k2-chelation,40 while green xanthate crystals retained the mode
at 2545 cm-1.
This implies distinct four- and five-coordinate geometries.
X-ray
crystallography confirmed square-planar N2S2 ligand fields for the dithiocarbamates
(Figure 7 and Figure 8), and a square-pyramidal N3S2 field (τ = 0.12)55 for the xanthate
(Figure 9), with k2- and k3-scorpionate ligands, respectively. The S,S'-chelates occupy cis
equatorial sites in the structures; the TpPh,Me ligand also occupies two equatorial sites,
leaving the third arm to variably interact with the axial site. The square planes were
distorted by the constrained S,S'-chelate bites; the cis S-Ni-S angles were 78.84(2)° and
78.06(2)° for TpPh,MeNiS2CNPh2 and TpPh,MeNiS2CNEt2, respectively, while N-Ni-N
angles were square (90.34(6)° and 90.32(6)°). Equatorial S-Ni-S and N-Ni-N angles of
the xanthate complex were 74.75(2)° and 87.54(7)°. (Table 4)
Compared
organoxanthate
to
the
square-planar
structure exhibits
dithiocarbamates,
elongated
coordinate
the
square-pyramidal
bonding,
consistent
a
paramagnetic (S = 1) Ni2+ ion resulting from transfer of one electron from the
destabilized axial dz2 lone pair into the equatorial dx2-y2 orbital. A similar structure was
reported for a Ni2+ xanthate complex cation supported by a neutral triazamacrocycle.56
45
Despite the chemical approximations in our modeling of the N3S23- ligand field, Ni-N and
Ni-S coordinate bond lengths in our complexes are comparable to those of corresponding
isomers of reduced NiSOD; the dithiocarbamate complexes compare to photoreduced
NiSOD,6,7,8 and the xanthate structure to DFT calculations on proposed paramagnetic
square-pyramidal catalytic intermediates.9,16
In contrast, more strongly σ-donating
equatorial ligands can enforce diamagnetism in an elongated square pyramid:9
[NEt4][TpMe,MeNi(CN)2] has short equatorial Ni-N bond lengths of 1.934(2) and 1.936(2)
Å, and a long axial bond of 2.389(2) Å;57 TpNi(PMe3)C6H5 has respective bond lengths
of 1.938(8), 1.979(9) and 2.57(1) Å.58
Crystallization of the model complexes in two different geometries is suggestive
of a facile axial equilibrium in solution.
Magnetic moments in CDCl3 solutions,
determined by the Evans NMR method,46 fell in a range of µeff = 2.5-2.7 µB at 295 K, less
than the spin-only limit. (Table 5)
Titration of TpPh,MeNiS2CNPh2 with equivalent
CF3CO2H in CH2Cl2 changed the solution from green to red with appearance of a ligand
field band at 490 nm (ε = 220 M-1 cm-1, Figure 10); the starting spectrum was recovered
by subsequent addition of NEt3. Similar spectral changes were elicited by heating the
solution. The equilibrium favors the green, paramagnetic square-pyramidal structure,
with the classical square-planar red form accumulating only at higher temperatures. This
is reversed from a related ring-distortion equilibrium of Cp*Ni(acac).59 Thermodynamic
parameters, ∆Ho = 2.2, 2.2 and 2.2 kcal/mole and ∆So = +6, +5 and +5 cal/moleK, for
TpPh,MeNiS2CNPh2, TpPh,MeNiS2CNEt2, and TpPh,MeNiS2COEt, respectively, were
determined. (Figure 11 and Figure 12).
These values reflect favorable entropy of
46
pyrazole dissociation offsetting combined unfavorable enthalpy of the Ni-N bond rupture
and spin crossover. Comparative values calculated for the corresponding axial base
equilibrium in reduced NiSOD are ∆Ho = 1.9 kcal/mole, ∆So = +11 cal/moleK.16 Cyclic
voltammetry of a NiSOD maquette in aqueous solution gave ∆Go = 1.6(5) kcal/mole for
the axial His-1 equilibrium at Ni2+.9
The crystal structures together correlate three motions germane to the equilibrium:
axial pyrazole rotation about its B-N bond; tilting of the equatorial plane; and inversion
of Ni2+ through this plane.
For TpPh,MeNiS2CNPh2, TpPh,MeNiS2CNEt2, and
TpPh,MeNiS2COEt respectively, H-B-N-N torsion angles into the axial pyrazole (i.e., using
the B-H bond as a center line) are 83.5°, 133.2°, and 175.1°. Coincident with inward
pyrazole rotation, the N2S2 equatorial plane is tilted; dihedral angles defined by a second
plane of the four equatorial nitrogen atoms are 130.44°, 140.02° and 146.01°,
respectively Ni2+ is displaced through the equatorial plane by distances of -0.121 Å, 0.013 Å and +0.304 Å. The axial pyrazole of TpPh,MeNiS2CNEt2 appears disposed to
minimize overlap of the dz2 lone pair with the pyrazole σ lone pair, as well as the
adjacent π orbital on the nitrogen proximal to boron. This is not possible in the bulkier
TpPh,MeNiS2CNPh2, which exhibits both a short separation of this proximal nitrogen from
nickel (2.997 Å), and short C•••H-C contacts between the axial pyrazole and the
opposing dithiocarbamate (i.e., C8-H43b, 2.779 Å).
Given the unusual Ni3+ ion of oxidized NiSOD and presumption of a fast oneelectron couple supporting a ping-pong mechanism (Scheme 1), we also investigated the
redox properties of our complexes. All three complexes exhibited quasi-reversible, one-
47
electron couples by cyclic voltammetry in CH2Cl2 solutions, with observed E°' values
reflecting relative donor strengths of the S,S'-chelates: TpPh,MeNiS2CNEt2, -0.08 V vs.
external Fc/Fc+; TpPh,MeNiS2CNPh2, +0.05 V; TpPh,MeNiS2COEt, +0.26 V. (Figure 13 and
Table 6)
These couples fall in a range suitable for SOD activity, suggesting our
complexes might function as catalysts under appropriate solvent conditions. Regardless,
our model complexes exhibit facile, tuneable oxidation and an axial equilibrium coupled
to spin crossover, which together mimic key properties of reduced NiSOD
intermediates.7,8,9,16
48
Figure 2. UV-Visible-NIR spectra (CH2Cl2, 295 K) of TpPh,MeNiS2CNEt2 (green),
TpPh,MeNiS2CNPh2 (red), and TpPh,MeNiS2COEt (black).
Table 1. Wavelength(nm) and molar extinction coefficient (mM-1cm-1) for TpPh,MeNi2+
complexes in DCM.
CH2Cl2, λmax, nm; ε, mM-1cm-1
TpPh,MeNiCl
242; 46.6
331; 1.2
486; 0.4
808; 0.09
915; 0.1
--
5/6
240; 60.3
323; 17.6
380; 3.0
397; 2.6
420; 1.5
642; 0.1
7/8
241; 55.8
297; 18.0
--
--
428; 1.6
655; 0.1
9
236; 55.7
289; 12.4
361; 1.0
--
431; 1.3
670; 0.1
10/11/12
239; 48.8
300; 8.5
360; 1.3
--
426; 0.7
649; 0.02
49
Figure 3. 1H NMR spectra (CDCl3, 295 K) of TpPh,MeNiS2CNEt2 (top),
TpPh,MeNiS2CNPh2 (middle), and TpPh,MeNiS2COEt (bottom).
Table 2. Selected chemical shifts (ppm) for TpPh,MeNi2+ complexes in CDCl3 at 295 K.
TpPh,MeNiCl
5/6
7/8
9
4-H
78.1
52.7
54.4
63.2
3-Ph,para
8.1
7.1
7.4
7.0
3-Ph,meta
8.7
6.8
6.9
6.9
3-Ph,ortho
9.7
4.7
4.5
4.0
5-Me
4.5
1.6
2.1
2.4
B-H
-13.6
-8.5
-8.3
-9.5
50
Figure 4. Solvent-dependent 1H NMR spectra (295 K) of TpPh,MeNiS2CNEt2 in CDCl3
(top), CD3CN (middle) and toluene-d8 (bottom).
51
Figure 5. Variable temperature 1H NMR spectra of TpPh,MeNiS2CNPh2 in CDCl3.
52
Figure 6. 1H NMR spectra (CDCl3, 295 K) of TpPh,MeNiS,S’-dithiolene.
p
Na
m
S
S
3
R
2+
N
4
N
5
Ni
N
R
R
N
4'
N N
B
H
3'
R=Ph
5'
Scheme 7. k2-TpPh,MeNi-S,S’-dithiolene.
53
Table 3. Selected chemical shifts (ppm) for TpPh,MeNi2+1,2-dithiolene in CDCl3 at 295 K.
#
ppm
3-ortho
7.1
3-meta
7.0
3-para
6.7
3’-ortho
8.6
3’-meta
7.6
3’-para
7.4
4
6.6
4’
6.3
5
2.8
5’
2.5
m
6.8
p
6.5
54
Figure 7. Perspective view of the molecular structure of complex 5 TpPh,MeNiS2CNEt2red with the atom labeling schemeThe thermal ellipsoids are scaled to enclose 30%
probability.
55
Figure 8. Perspective view of the molecular structure of complex 7 TpPh,MeNiS2CNPh2red with the atom labeling scheme. The thermal ellipsoids are scaled to enclose 30%
probability.
56
Figure 9. Perspective view of the molecular structure of complex 9 TpPh,MeNiS2COEt
with the atom labeling scheme. The thermal ellipsoids are scaled to enclose 30%
probability.
57
Table 4. Selected bond lengths (Å) and angles (º) for complexes 5, 7 and 9.
Complex 5
Ni(1)-N(1)
1.929(1)
Ni(1)-N(3)
1.934(1)
Ni(1)-S(2)
2.1929(5)
Ni(1)-S(1)
2.1990(5)
S(1)-C(31)
1.706(2)
S(2)-C(31)
1.710(2)
N(7)-C(31)
1.318(2)
N(1)-Ni(1)-N(3)
90.32(6)
N(1)-Ni(1)-S(2)
95.73(4)
N(3)-Ni(1)-S(2)
172.46(5)
N(1)-Ni(1)-S(1)
172.86(4)
N(3)-Ni(1)-S(1)
96.16(4)
S(2)-Ni(1)-S(1)
78.061(18)
C(31)-S(1)-Ni(1)
86.65(6)
C(31)-S(2)-Ni(1)
86.76(6)
Ni(1)-N(1)
1.9100(15)
Ni(1)-N(3)
1.9107(14)
Ni(1)-S(2)
2.1832(5)
Ni(1)-S(1)
2.2013(5)
S(1)-C(31)
1.701(2)
S(2)-C(31)
1.704(2)
N(7)-C(31)
1.333(3)
N(1)-Ni(1)-N(3)
90.34(6)
N(1)-Ni(1)-S(2)
94.38(5)
N(3)-Ni(1)-S(2)
170.65(5)
N(1)-Ni(1)-S(1)
171.34(5)
N(3)-Ni(1)-S(1)
95.64(5)
S(2)-Ni(1)-S(1)
78.84(2)
C(31)-S(1)-Ni(1)
84.70(7)
C(31)-S(2)-Ni(1)
85.19(6)
Ni(1)-N(3)
2.042(2)
Ni(1)-N(1)
2.052(2)
Ni(1)-N(5)
2.078(2)
Ni(1)-S(2)
2.3794(6)
Ni(1)-S(1)
2.3991(6)
S(1)-C(31)
1.679(2)
S(2)-C(31)
1.683(2)
O(1)-C(31)
1.329(3)
N(3)-Ni(1)-N(1)
91.80(7)
N(3)-Ni(1)-N(5)
87.54(7)
N(1)-Ni(1)-N(5)
92.17(7)
N(3)-Ni(1)-S(2)
158.70(5)
N(1)-Ni(1)-S(2)
109.22(5)
N(5)-Ni(1)-S(2)
94.89(5)
N(3)-Ni(1)-S(1)
98.79(5)
N(1)-Ni(1)-S(1)
99.95(5)
N(5)-Ni(1)-S(1)
166.09(5)
S(2)-Ni(1)-S(1)
74.75(2)
C(31)-S(1)-Ni(1)
82.58(8)
C(31)-S(2)-Ni(1)
83.13(8)
Complex 7
Complex 9
58
Table 5. Magnetic moments measured in CDCl3 at 295 K by Evans method.
n
S
µs60
µeff
TpMe,MeNiS2COMe
2
1
2.83
2.67µB
TpMe,MeNiS2COEt
2
1
2.83
2.71µB
Tp
Me,Me
NiS2CNEt2
2
1
2.83
2.75µB
Tp
Me,Me
NiS2CNPh2
2
1
2.83
2.76µB
TpPh,MeNiS2CNMe2
2
1
2.83
2.77µB
TpPh,MeNiS2CNEt2
2
1
2.83
2.52µB
TpPh,MeNiS2CNPh2
2
1
2.83
2.49µB
2
1
2.83
2.71µB
TpPh,MeCoS2CNEt2
3
3/2
3.87
4.12µB
TpPh,MeCoS2CNPh2
3
3/2
3.87
4.20µB
TpPh,MeCoS2COEt
3
3/2
3.87
4.31µB
Tp
Ph,Me
NiS2COEt
59
2.0
0.3
2.0
-1
-1
ε (mM cm )
1.5
0.2
1.0
0.1
0.5
500 nm
428 nm
1.5
1.0
0.0
0.0
0.5
1.0
1.5
Added acid (equiv.)
0.0
2.0
0.5
0.0
400
500
600
700
800
900
Wavelength (nm)
Figure 10. Titration of TpPh,MeNiS2CNPh2 with CF3CO2H in CH2Cl2 at 20ºC. The dashed
line shows the final spectrum after the addition of 2.0 equiv of NEt3. The inset shows
extinctions against added proton equivalents at 428 nm (square, left axis) and 500 nm
(triangle, right axis).
60
Figure 11. UV-Visible-NIR spectra of TpPh,MeNiS2CNPh2, recorded in CH3CN at 10 K
intervals from 20 to 70ºC.
Figure 12. Van’t Hoff plot for the axial base equilibrium of TpPh,MeNiS2CNPh2 shown in
Figure 36 (Aon = 0.640, Aoff = 0.151, R2 = 0.9993).
61
1.50
1.25
1.00
0.75
0.50
0.25
0.00
-0.25
-0.50
Potential (V)
Figure 13. Cyclic voltammograms of 5 (green) and 9 (black).
Table 6. Oxidation and reduction properties of modeling Ni2+ and Co2+ complexes.
E1/2 in V vs Ag/AgCl in 0.1M TBAPF6 DCM at 295 K
Tp
Me,Me
Ni2+
TpPh,MeNi2+
TpPh,MeCo2+
3
4
2
5
7
9
15
16
17
E1/2
0.59
0.49
0.82
0.35
0.48
0.69
0.28
0.38
0.63
∆Ep
0.07
0.08
0.12
0.10
0.08
0.09
0.06
0.07
0.09
62
CHAPTER IV: SCORPIONATE-SUPPORTED MODELS OF NICKELDEPENDENT SUPEROXIDE DISMUTASE
Introduction
The recently characterized active site of a nickel-dependent superoxide dismutase
(NiSOD) consists of an unusual resting state Ni3+ ion stabilized by a square-pyramidal
(N3S2)3- ligand field.7,8 This donor set is derived from the N-terminus amine, a His-1
imidazole, the adjacent deprotonated backbond imide, and two thiolates from Cys-2 and
Cys-6 residues. The cysteine thiolates occupy equatorial positions in a cis orientation,
while the nitrogen donors form a facial array with the imidazole occupying the axial
position. The axial imidazole dissociates in a photoreduced Ni2+ state, but may remain
attached in the reduced catalytic intermediate obtained during substrate turnover.9,16 As
the NiSOD active site represents a new redox center unprecedented in structural biology,
even in comparison to other known superoxide dismutases,5 the structure and dynamics
of this site comprise a compelling target for biomimetic studies.
The monoanionic facial array of nitrogen donors in NiSOD immediately reminded
us of Trofimenko’s hydrotris(pyrazolyl)borate (i.e., Tp) ligands;61 in particular, we
anticipated a “scorpionate” equilibrium between k2 and k3 binding modes,35 modeling the
proposed dynamics of the axial His-1 sidechain in the reduced enzyme.16 Using hydro(3phenyl-5-methylpyrazolyl)borate (i.e., TpPh,Me) in conjunction with zwitterionic
organoxanthate and dithiocarbamate co-ligands as cis-bis(sulfur) chelates, we previously
obtained pentacoordinate paramagnetic (S = 1) solid-state structures with an effectively
trianionic N3S2 ligand field for the O-ethylxanthate complex, and a diamagnetic square-
63
planar N2S2 ligand field with a detached pyrazole arm for N,N-diethyl- and diphenyldithiocarbamate complexes.36 These limiting structures were indeed found to equilibrate
in solution, exhibiting spin crossover coupled to an axial base ligation, as well as quasireversible one-electron redox couples at modest anodic potentials.
In the present work, we substitute the sterically less demanding hydrotris(3,5dimethylpyrazolyl)borate ligand to obtain paramagnetic pentacoordinate N3S2 structures
for both xanthate and dithiocarbamate co-ligands in the solid state. However, these
structures exhibit variable distortion towards a trigonal bipyramidal geometry due to
enhanced rotation of the dithioacid chelates relative to the scorpionate face. Evidence
was found nonetheless for retention of the spin equilibrium and a one-electron redox
couple in solution. These observations allow us to consider steric effects arising from a
pattern of 3-pyrazole ring substitution on the structure and dynamics of the biomimetic
complexes.
Experimental
Electrochemistry. Cyclic voltammetry was performed using a CH Instruments
CH1730A workstation. Data were recorded at room temperature in CH2Cl2 with 0.1 M
Bu4NPF6 supporting electrolyte using platinum working and counter electrodes and a
Ag/AgCl reference electrode, at scan speeds of 50-200 mV/s.
Quasi-reversible one
electron processes were observed for all four complexes: 1, Eº′ = +0.38 V vs. external
Fc/Fc+, ∆E = 0.11 V, ipa/ipc = 1.17; 2, Eº′ = +0.39 V, ∆E = 0.12 V, ipa/ipc = 1.40; 3, Eº′ =
+0.16 V, ∆E = 0.08 V, ipa/ipc = 1.02; and 4, Eº′ = +0.06 V, ∆E = 0.09 V, ipa/ipc = 0.99.
64
Magnetic susceptibility. Solid-state magnetic susceptibility measurements on 1
were performed on a 7 T Quantum Design MPMS SQUID magnetometer (GTY).
Measurements of magnetization as a function of temperature were performed from 5 to
300 K and in a 5000 G field. Samples of TpMe,MeNiS2COMe were prepared as a fine
powder. The sample was packed between cotton plugs, placed into gelatin capsules,
cooled in zero applied field, and measured upon warming. Diamagnetic corrections were
applied on the basis of Pascal’s constants. The data were corrected for the diamagnetism
of the gel cap and the cotton plug. Solution measurements were made by the Evans
NMR method.46
X-ray crystallography. Diffraction-quality crystals of 1 and 3 were grown by
slow evaporation of CH3CN solutions. The structure of TpMe,MeNiS2COMe (1) was
determined at the 2007 Summer Crystallography School at the University of California
San Diego Small Molecule Crystallography Facility, directed by Professor Arnold L.
Rheingold (MPJ). A single green block (0.20 x 0.30 x 0.45 mm) was mounted on a
cryoloop with Paratone-N oil and optically aligned on the four-circle of a Siemens P4
diffractometer equipped with a SMART CCD detector, a graphite monochromator, a Mo
Kα radiation source (λ = 0.71073 Å), and a low-temperature (170 K) gas stream. The
SMART program package was used to determine unit cell parameters and to collect
data.62 The raw frame data were processed using SAINT and a multi-scan absorption
correction was applied by SADABS.62 Data preparation was carried out by using the
program XPREP.62 The space group was determined to be P21/n, a non-standard setting
of P21/c (No. 14). The structure was solved using direct methods and difference Fourier
65
techniques under SHELXTL.63 All non-hydrogen atoms were located and anisotropically
refined. The boron hydride atom was also located in a difference map while the other
hydrogens were introduced in ideal positions.
A total of 15044 reflections were
collected, with 5042 being independent (Rint = 0.0291). The refinement converged to
give R1 = 0.0409, wR2 = 0.1045 (all data), GoF = 1.089. Crystal data: C17H25BN6NiS2,
formula weight 463.07, monoclinic, P21/n, a = 7.817(1) Å, b = 18.939(3) Å, c =
14.405(2) Å, β = 91.004(2)º, V = 2132.1 Å3, Z = 4, Dcalc = 1.443 g/cm3, µ = 11.3 cm-1.
The structure of TpMe,MeNiS2CNEt2 (3) was determined at West Virginia
University (JLP). A single green block (0.22 x 0.32 x 0.40 mm) was washed with
perfluoropolyether PFO-XR75 (Lancaster) and sealed under nitrogen in a glass capillary.
The sample was optically aligned on the four-circle of a Siemens P4 diffractometer
equipped with a graphite monochromator, a monocap collimator, a Mo Kα radiation
source (λ = 0.71073 Å), and a SMART CCD detector. The program SMART (version
5.6) was used for diffractometer control, frame scans, indexing, orientation matrix
calculations, least-squares refinement of cell parameters, and the data collection.62 An
semi-empirical absorption correction was applied using the SADABS routine available in
SAINT.64 The data were corrected for Lorentz and polarization effects. No evidence of
crystal decomposition was observed. Data preparation was carried out by using the
program XPREP.62 The orthorhombic space group was determined to be P212121 (No.
19). The structure was solved by a combination of direct methods and difference Fourier
analysis with the use of SHELXTL 6.1.63 Hydrogen atoms were included as fixed
contributions using a riding model with isotropic temperature factors set at 1.2
66
(methylene protons, aromatic protons, and B-H) or 1.5 (methyl protons) times that of the
adjacent non-hydrogen atom.
The positions of the methyl hydrogen atoms were
optimized by a rigid rotating group refinement with idealized tetrahedral angles. One of
the two ethyl groups attached to N(7) suffers from a two-site (2:1) conformational
disorder. The C-C and C-N distances associated with this ethyl group, which contains
carbons C(19) and C(20), were restrained to 1.54 ± 0.02 Å and 1.46 ± 0.02 Å,
respectively, during the full-matrix least-squares refinement. The linear absorption
coefficient, atomic scattering factors, and anomalous dispersion corrections were
calculated from values found in the International Tables of X-ray Crystallography.65 A
total of 15529 reflections were collected with 5575 being independent (Rint = 0.0344).
The refinement converged to give R1 = 0.0426, wR2 = 0.0995 (all data), GoF = 1.039.
Crystal data:
C20H32BN7NiS2, formula weight 504.17, orthorhombic, P212121, a =
7.9253(4) Å, b = 11.2651(7) Å, c = 28.346(2) Å, V = 2530.7(2) Å3, Z = 4, Dcalc = 1.323
g/cm3, µ = 9.53 cm-1.
Results and Discussion
We prepared and characterized several neutral complexes with N3S2 ligand fields
as NiSOD mimics. The ligand set is provided by the scorpionate anion TpMe,Me and
zwitterionic
heteroatom-substituted
dithiocarbamates.
dithioacids,
either
organoxanthates
or
Lime-green product complexes, include TpMe,MeNiS2COMe (1),
TpMe,MeNiS2COEt (2), TpMe,MeNiS2CNEt2 (3), and TpMe,MeNiS2CNPh2 (4) were prepared
by metathesis of TpMe,MeNiCl with sodium salts of the xanthates and dithiocarbamates.
The series of dithioacid co-ligands includes a range of steric and electronic properties,
67
which in conjunction with previously reported models supported by the bulky TpPh,Me
scorpionate ligand,36 will enable steric and electronic manipulation of phenomena
potentially relevant to the mechanism of NiSOD turnover; these particularly include
structure, ligand field dynamics, substrate binding, and redox reactivity. Trofimenko and
coworkers previously reported the synthesis of a closely related dithiocarbamate complex
L*NiS2CNEt2, L* = hydrotris(3-isopropyl-4-bromopyrazolyl)borate.66
X-ray crystallography
Structures of the O-methylxanthate and N,N-diethyldithiocarbamate complexes (1
and 3, respectively) were determined (Figure 14).
Both complexes adopt a five-
coordinate geometry in the solid state with k3-TpMe,Me chelation, analogous to previously
reported TpPh,MeNiS2COEt (i.e., 2′, the analog of 2). Like 2′, Ni-N and Ni-S coordinate
bond lengths respectively exceeding 2.0 and 2.3 Å (Table 7) are consistent with high-spin
Ni2+ (S = 1).36,53,54
In contrast, shorter coordinate bond lengths and k2-scorpionate
bonding were found in dithiocarbamate complexes of the TpPh,Me ligand (3′ and 4′),
consistent with a classical square-planar diamagnetic structure.36
Unlike 2′, the present structures exhibit significant distortion towards a trigonal
bipyramidal geometry. The N3-Ni1-S2 bond angles (175.58(4)º in 1 and 171.95(6)º in 3,
Table 7) comprise an axial vector in both complexes, and N1, N5 and S1 define an
equatorial donor plane, which is severely distorted by the restricted chelate bite angles.
In particular, the equatorial N1-Ni1-N5 angle, 95.50(6)º in 1, is constrained within the
scorpionate. This angle nonetheless is opened significantly compared to the nearly ideal
square angles to the axial pyrazole donor: N1-Ni1-N3, 89.05(6)º; N5-Ni1-N3, 88.18(6)º.
68
The dithioacid chelate also yields a constrained S-Ni-S angle, 73.65(2)º in 1 and
73.99(3)º in 3. The three equatorial bond angles together average 119.5º in 1, but owing
to constraints of the chelates, the individual angles range from 95.50(6)º to 141.94(5)º.
Thus, the respective τ values of 0.56 and 0.31 for 1 and 3 reflect significant structural
contribution from a square planar geometry with an axial N1 donor and a basal plane
circumscribed by N3, N5, S1 and S2.55 A limiting square pyramidal geometry was
previously defined in 2′, consistent with its τ value of 0.11.
The increased trigonal distortion from 3 to 1 is accompanied by significant bond
lengthening along the resulting axis. For example, the Ni-S bond distances are 2.5197(6)
Å (axial, Ni1-S2) and 2.3404(6) Å (equatorial, Ni1-S1) in 1, compared to 2.4099(7) Å
and 2.3747(8) Å in 3. The C-S bond lengths are also differentiated within the chelate,
1.6654(2) Å (axial, C16-S2) and 1.704(2) Å (equatorial, C16-S1). Similarly, the axial
Ni-N bond length is 2.058(2) Å (Ni1-N3) in 1, compared to the shorter equatorial bonds
of 2.016(2) Å (Ni1-N1) and 2.012(2) Å (Ni1-N5); corresponding distances in 3 are
2.065(2), 2.027(2), and 2.063(2) Å with a short apical distance in a square pyramid. This
has direct consequences towards the electronic structure; an expanded trigonal axis
stabilizes the coincident dσ* orbital, enforcing approximate 2:1:2 ligand field splitting
and a paramagnetic (S = 1) ground state. In contrast, trigonal bipyramidal dithioacid
complexes supported by triphos exhibit a contracted axis and a diamagnetic ground
state,67,68 consistent with 2:2:1 splitting and a destabilized dσ* LUMO.
The factors determining the observed range of trigonal distortion are difficult to
assess.
Pentacoordinate d8 complexes frequently exhibit dynamic geometric
69
rearrangements,43,69 with the limiting square-planar and trigonal-bipyramidal geometries
typically calculated to lie at nearly degenerate energies with small barriers to
interconversion.69-72 A structural overlay of the organoxanthate complexes 1 and 2′ is
consistent with facile turnstile rotation of the dithioacid chelate relative to the
scorpionate, which displaces the dithioacid plane from a colinear to an orthogonal
position relative to one edge of the facial N3 array (Figure 15). Nonbonding S•••C
contacts between the dithioacid and the pyrazole 3-methyl substituents of 1 and 3
approach the van der Waals limit, in the range of 3.35-4.07 Å, compared to S•••Cipso
contacts of 3.27-4.05 Å with the 3-phenyl substituents in 2′. A decisive steric factor
arising from the pyrazole substituents is therefore not immediately evident in the
coordination geometries.
The relative size of the 3-pyrazole substituents should affect a related steric
phenomenon of direct relevance to potential SOD catalysis.
Ni2+ complexes of the
relatively unhindered TpMe,Me ligand and related scorpionates with bidentate nitrite and
acetate ligands are known to reversibly bind small solvent molecules such as CH3CN and
CH3OH to form octahedral complexes.73 Transient ligation of superoxide in a similar
geometry would be necessary to accommodate inner-sphere redox processes. The bulky
3-phenyl substituents block access to the sixth open site of 2′, but the smaller methyl
substituents of 3 should accommodate small linear ligands (Figure 16).
However,
increased distortion of 2 toward a trigonal bipyramidal geometry introduces steric
hindrance from the equatorial sulfur. It seems quite plausible that fine tuning of the
pentacoordinate geometry and the axial site accessibility in the model complexes using
70
pyrazole substitution may enable discrimination of inner- and outer-sphere substrate
turnover mechanisms in biomimetic SOD catalysis.
UV-Visible spectroscopy
Solution electronic spectra of 1-4 were recorded in non-polar solvents (e.g.,
CH2Cl2, Figure 17, Table 8). These spectra are remarkably similar to those of the
TpPh,Me-supported congeners, except for the absence of a broad, strong UV band
apparently associated with the 3-phenyl substituents (λmax = 240 nm, ε ≈ 6 x 104 M-1 cm1 36
).
Instead, a common sharp underlying band was observed at 230 nm (ε = 1.8-2.5 x
104 M-1 cm-1) for 1-4. Three additional bands common to complexes of both scorpionates
were observed at monotonically decreasing energy and extinction. For 2, these were
observed at 292 nm (1.2 x 104 M-1 cm-1), 415 nm (7 x 102 M-1 cm-1) and 662 nm (1.4 x
102 M-1 cm-1). The positions of these bands are only slightly shifted compared to their
counterparts in the spectrum of 2′, at 289, 431 and 670 nm, notwithstanding the
difference in organoxanthate coordination observed in the solid state for 1 and 2′. Thus,
the spectra are consistent with predominant five-coordinate structures for 1-4 in solution,
but are not indicative of the actual geometries.
The prominent 292 nm peak of 2 is flanked by at least two poorly resolved bands.
Comparable bands were not observed in other pentacoordinate Ni2+ scorpionate
complexes,53,54 so these features must arise specifically from the presence of the xanthate
and dithiocarbamate chelates. Three prominent UV bands with comparable extinctions in
homoleptic bis- and tris-xanthato Ni2+ complexes have been assigned as S-Ni LMCT,
intraligand S π- π *, and Ni-S MLCT with increasing energy.74,75 In spectra of the
71
TpPh,Me-supported analogues, the prominent band red-shifted with increasing dithioacid
donor strength (i.e., 2′ < 4′ < 3′), consistent with Ni-S LMCT character.36 However, this
trend is partially reversed in the TpMe,Me-supported congeners (i.e., 3 < 4 ≈ 2), which
yields a significant difference between 3 and 3′ (278 nm vs. 323 nm, respectively), but
not 2 and 2′ (292 nm vs. 290 nm), or 4 and 4′ (292 nm vs. 296 nm) despite the change in
scorpionate ligands.45,53 Therefore, the overall feature may reflect a superposition of
charge transfer and ligand-centered transitions.
Assignment of the intermediate band, at 415 nm for 2, is similarly problematic.
This feature exhibits a weak red shift with increasing dithioacid donor strength in the
TpPh,Me complexes (i.e., 3′ < 4′ < 2′) consistent with ligand field character,36 but this
pattern is again reversed in the TpMe,Me analogues (i.e., 2 < 3 < 4), suggestive of charge
transfer character. Moreover, the extinction of this feature is intermediate between values
typically associated with ligand field and LMCT bands. Thus, disparate assignments
have been made to similar bands in related complexes.56,74 Finally, the weak low energy
band, at 664 nm for 2, is clearly a ligand field transition,36,53,54 exhibiting a red shift with
decreasing dithioacid donor strength for both scorpionates (e.g., 3 < 4 < 2). Overall, the
UV-visible
spectra
are
generally
consistent
with
high-spin
pentacoordinate
complexes;36,53,54 some systematic trends in band positions were evident, but correlations
encompassing the disparate scorpionate and dithioacid chelates, and predictive within the
range of possible geometries, could not be deduced.
IR spectroscopy
72
The complexes 1-4 were also characterized by IR spectroscopy in the solid state
in KBr pellets. The diagnostic ν(B-H) mode appeared between 2514-2521 cm-1 for all
four complexes, consistent with k3-scorpionate coordination evident in the crystal
structures of 1 and 3.36,40 Organoxanthates coordinated to high-spin Ni2+ exhibit three
diagnostic modes over a 1000-1300 cm-1 range, including C=S, C-O, and C-O-R stretches
at increasing energies.75 These were clearly observed in a spectrum of 1 at 1053, 1171,
and 1228 cm-1, respectively; the corresponding peaks in a spectrum of 2 were observed at
1040, 1124, and 1222 cm-1.
In comparison, dithiocarbamates generally yield two
diagnostic modes with predominant C=S and C-NR2 stretching character near 980 and
1500 cm-1, respectively.51 Compared to the xanthates, the first of these was quite weak; a
corresponding band was observed for 3 at 998 cm-1, but that of 4 was not resolved. The
latter stretching mode was observed at 1497 cm-1 for 3 and 1490 cm-1 for 4. The N,Ndiphenyl substituents of 4 also give rise to a unique aromatic C=C stretching mode at
1592 cm-1.
In summary, the IR data are entirely consistent with the formulations of
complexes 1-4, and with pentacoordinate geometries.
1
H NMR spectroscopy
Consistent with a paramagnetic (S = 1) ground state, complexes 1-4 displayed
shifted resonances in 1H NMR spectra (Figure 18, Table 9). Nevertheless, these are
readily interpreted given the assigned formulations. Despite the low static symmetry of
the complexes, the TpMe,Me ligand gives rise to only four resonances common in all the
spectra, consistent with dynamic equivalence of the three pyrazole rings. Thus, dynamic
rotation of the dithioacid relative to the scorpionate face must be facile. The borohydride
73
and 3-methyl resonances are relatively broad and shifted somewhat upfield, while the 5methyl signal is sharper and shifted only slightly downfield. In contrast, the 4-proton
attached directly to the aromatic pyrazole ring is shifted considerably downfield.
Resonances assignable to the organic substituents on the dithioacid chelates were also
observed. For example, an O-methyl signal was observed at 27.1 ppm in the spectrum of
1. The N,N-diethyl resonances of the dithiocarbamate complex 3 were shifted downfield
to a greater extent than the O-ethyl resonances of the xanthate complex 2, consistent with
the greater basicity of the former. Corresponding attenuation of the pyrazole resonances
was also observed. These observations are consistent with a contact shift mechanism,
with significant delocalization of spin density onto the scorpionate and dithioacid ligands.
Magnetism
Magnetic moments of complexes 1-4 were determined in CDCl3 solutions at room
temperature by the Evans NMR method.46 These fell in a narrow range of µeff = 2.672.76 µB, which is slightly less than the spin-only limit for two unpaired electrons (S = 1,
2.83 µB). The corresponding TpPh,Me-supported analogues 2′-4′ gave values of µeff =
2.49-2.71 µB, with the dithiocarbamate chelates in particular exhibiting lower solution
susceptibilities. A rapid scorpionate equilibrium between diamagnetic and paramagnetic
states in solution with respective k2- and k3-scorpionate ligation was demonstrated for
these analogues, and diamagnetic k2 square planar structures were obtained in the solid
state for the dithiocarbamate complexes 3′ and 4′.36 A similar axial equilibrium was
proposed for the reduced catalytic intermediate of NiSOD.16
Accumulation of a
diamagnetic fraction would result in the low average solution susceptibilities.
74
Given the possibility of a comparable equilibrium with the TpMe,Me-supported
complexes in the present work, temperature-dependent magnetic susceptibility was
measured for 1 in the solid state (Figure 19), for which a static pentacoordinate
paramagnetic ground state structure is demonstrated (vide supra). The data are consistent
with Curie-Weiss behavior with no evidence of spin crossover; the fit yields 1.42 emuK/mol, equivalent to µeff = 3.37 µB, with ſ = -6.1 K. This value is consistent with
previously observed g values for five-coordinate Ni2+, which are in the neighborhood of
2.2-2.3, yielding an effective moment of 3.1-3.3 µB.76
The lower solution values obtained for 1-4 are also suggestive of a dynamic
equilibrium, which yields a constant, ca. 20 mole percent fraction of the diamagnetic
isomer at room temperature. Thermodynamic data for the equilibrium of 4′ derived from
temperature-dependent optical data estimate a paramagnetic mole fraction of 69%.36 By
comparison, the ratio of µeff = 2.49 µB determined in solution for 4′,36 over the limiting
solid state value obtained herein for 1, is 74%. These results are consistent with shift of
an equilibrium towards the pentacoordinate paramagnetic isomer for the dithiocarbamate
complexes 3 and 4 compared to their TpPh,Me-supported analogues, which may reflect
reduced steric hindrance towards axial pyrazole ligation in the k3-scorpionate
coordination mode and secondarily, the relative donor strengths of the dithiocarbamate
and xanthate chelates.
Cyclic voltammetry
The redox behavior of complexes 1-4 is relevant to potential utility of the
complexes as dismutation catalysts in future modeling of NiSOD activity.
Quasi-
75
reversible one electron couples were observed for all four complexes; the observed
anodic potentials clearly reflect the relative donor strengths of the dithioacid chelates
(Figure 20). The redox couples lie at potentials suitable for superoxide dismutation, and
could be exploitable for this purpose under suitable solvent conditions. Moreover, these
couples are only slightly shifted anodically from those of the TpPh,Me-supported
congeners,36 so the present complexes will exhibit comparable redox reactivity, but with
diminished steric impediment to inner-sphere electron transfers.
Conclusion
Trofimenko’s hydrotris(3,5-dimethylpyrazolyl)borate ligand in combination with
organoxanthate or dithiocarbamate co-ligands affords access to pentacoordinate Ni2+
complexes with formally trianionic N3S2 ligand fields.
complexes supported
by the
bulkier
scorpionate
Compared to analogous
ligand
hydrotris(3-phenyl-5-
methylpyrazolyl)borate that adopt either diamagnetic square-planar or paramagnetic
square pyramidal geometries,36 the TpMe,Me analogues favor the pentacoordinate high-spin
states, which twist into a trigonal bipyramidal geometry. Nevertheless, solution-phase 1H
NMR and UV-Vis spectra, and redox behavior of the complexes are not significantly
different. These complexes accordingly model redox reactivity and ligand field dynamics
proposed for reduced NiSOD. In particular, quasi-reversible redox couples observed by
cyclic voltammetry fall at potentials suitable for reactivity with superoxide, and can be
adjusted by over 300 mV. Furthermore, evidence for spin crossover mediated by a
scorpionate equilibrium (i.e., by disparate k2- and k3-coordination modes) was obtained,
analogous to the axial His-1 dissociation evident in photoreduced NiSOD.7,8
76
Substitution of zwitterionic heteroatom-conjugated dithioacids in place of the
equatorial cysteine donors affords, besides synthetic convenience, the biomimetic
phenomena just enumerated.
This may seem surprising, given that xanthates and
dithiocarbamates are less basic than anionic cysteine thiolates.77 However, the latter may
be protonated upon reduction in the NiSOD cycle, and pyrazole donors in the models
may constitute relatively poor π-acids compared to the opposing equatorial amide in the
enzyme ligand field. DFT calculations on the free N,N-dimethyldithiocarbamate anion
and its diamagnetic homoleptic Ni2+ complex show that the nitrogen atom does not
significantly contribute to frontier donor orbitals.78 Hence, the bonding topologies of
these chelates effectively approximate that of separate sulfur donor atoms.
The
scorpionate ligand itself comprises a facial monoanionic array of nitrogen donors akin to
the remainder of the NiSOD ligand field.
Taken together, these factors enable the
synthetic complexes to successfully mimic the structure, ligand field dynamics, and redox
properties of the metalloenzyme.
A cogent issue in SOD catalysis is the question of inner- and outer-sphere
substrate turnover mechanisms. Our structural results also indicate that access to a sixth
axial site in the pentacoordinate model complexes can be manipulated by simply
changing the 3-pyrazole substituents. Moreover, the facile trigonal bipyramidal twisting
of the N3S2 ligand field observed in the present work will also be a factor.
Such
rearrangement is clearly constrained in the enyzme active site, and it is tempting to
suggest this is necessary to accommodate inner-sphere electron transfers at octahedral
nickel. On the other hand, the model complexes are highly fluxional, and the trigonal
77
bipyramidal geometry may lie at the periphery of the productive reaction pathway. The
next goal of our ongoing investigation is the identification of suitable conditions for
functional modeling of NiSOD, in order to examine such issues.
78
Figure 14. ORTEP diagrams of 1 and 3, drawn with 50% thermal ellipsoids.
Figure 15. Overhead ball-and-stick views of 2′ (left) and 1 (right) and a side-on
wireframe overlay plot (center), emphasizing rotation of the organoxanthate chelates with
respect to the N3 scorpionate faces.
79
Figure 16. Space-filling diagrams of 2′ (left), 1 (center), and 3 (right) from an axial
perspective toward the open octahedral site, emphasizing the steric effects of 3-pyrazole
substituents and dithioacid chelate rotation on its accessibility.
80
Table 7. Selected bond lengths (Å) and angles (°) for complexes 1 and 3.
Complex 1
Ni(1)-N(1)
2.016(2)
Ni(1)-N(3)
2.058(2)
Ni(1)-N(5)
2.012(2)
Ni(1)-S(2)
2.5197(6)
Ni(1)-S(1)
2.3404(6)
S(1)-C(16)
1.704(2)
S(2)-C(16)
1.665(2)
O(1)-C(16)
1.319(2)
S(2)-Ni(1)-N(3)*
175.58(4)
S(1)-Ni(1)-N(3)
102.03(4)
N(1)-Ni(1)-N(3)
89.05(6)
N(5)-Ni(1)-N(3)
88.18(6)
S(2)-Ni(1)-N(1)
94.02(5)
S(2)-Ni(1)-N(5)
94.69(5)
S(2)-Ni(1)-S(1)
73.65(2)
S(1)-Ni(1)-N(1)
120.92(4)
S(1)-Ni(1)-N(5)*
141.94(5)
N(1)-Ni(1)-N(5)
95.50(6)
S(2)-C(16)-S(1)
119.9(1)
S(2)-C(16)-O(1)
124.7(2)
S(1)-C(16)-O(1)
115.4(1)
τ* = 0.56
Complex 3
Ni(1)-N(1)
2.027(2)
Ni(1)-N(3)
2.065(2)
Ni(1)-N(5)
2.063(2)
Ni(1)-S(2)
2.4099(7)
Ni(1)-S(1)
2.3747(8)
S(1)-C(16)
1.710(3)
S(2)-C(16)
1.707(3)
N(7)-C(16)
1.329(4)
S(2)-Ni(1)-N(3)*
171.95(6)
S(1)-Ni(1)-N(3)
99.59(6)
N(1)-Ni(1)-N(3)
88.68(8)
N(5)-Ni(1)-N(3)
88.39(8)
S(2)-Ni(1)-N(1)
98.19(6)
S(2)-Ni(1)-N(5)
95.33(6)
S(2)-Ni(1)-S(1)
73.99(3)
S(1)-Ni(1)-N(1)
112.05(7)
S(1)-Ni(1)-N(5)*
153.27(7)
N(1)-Ni(1)-N(5)
93.47(9)
S(2)-C(16)-S(1)
114.8(1)
S(2)-C(16)-N(7)
122.7(2)
S(1)-C(16)-N(7)
122.4(2)
τ* = 0.31
*τ = [<(L-M-L)ax - <(L-M-L)eq]/60
81
Figure 17. UV-visible spectra (CH2Cl2, 295 K) of 2 (dashed black line), 3 (solid gray)
and 4 (solid black line).
Table 8. Wavelength(nm) and molar extinction coefficient (mM-1cm-1) for TpMe,MeNi2+
complexes in DCM.
CH2Cl2, λmax, nm; ε, mM-1cm-1
TpMe,MeNiCl
232; 8.8
254; 7.2
286; 2.3
333; 0.7
483; 0.4
800; 0.1
1
230; 14.4
260; 6.6
292; 8.5
415; 0.6
655; 0.1
--
2
231; 18.4
261; 9.4
292; 11.5
415; 0.7
662; 0.1
--
3
230; 17.9
--
278; 15.2
420; 0.8
644; 0.1
--
4
230; 25.6
--
292; 20.6
426; 1.2
651; 0.1
--
82
Figure 18. 1H NMR spectra (CDCl3, 295 K) of 1-4 (bottom to top, respectively). Peaks
arising from the 3-5 pyrazole ring positions and solvent (s) are labeled.
Table 9. Selected chemical shifts (ppm) for TpMe,MeNi2+ complexes in CDCl3 at 295 K.
TpMe,MeNiCl
1
2
3
4
4-H
82.5
67.4
67.1
63.1
63.6
5-Me
6.1
1.5
1.4
0.3
0.6
3-Me
-8.1
-7.9
-7.9
-7.7
-7.7
B-H
-13.0
-9.2
-9.3
-9.8
-9.5
83
Figure 19. Solid-state temperature-dependent magnetic susceptibility data for 1.
Figure 20. Cyclic voltammograms of 1 (bottom) and 3 (top).
84
CHAPTER V: SOLID-STATE SPIN CROSSOVER OF Ni2+ IN A
BIOINSPIRED N3S2 LIGAND FIELD
Spin crossover is of interest as a means to obtain bistable molecular switches for
nanoscale devices.79,80 Cooperative intermolecular behavior in the solid-state leads to
abrupt spin transitions that display thermal hysteresis, enabling bistability and optical
switching.81 This phenomenon is usually defined to include 3d4-3d7 transition metal ions
that can adopt physically distinct high- and low-spin states based on t2g→eg valence
electron promotion in octahedral ligand fields.79-82 In contrast, "anomalous magnetism"
of d8 Ni2+ complexes typically involves a conformational change,82,83 for example,
(Ph2BnP)2NiBr2 crystallizes as a mixture of square-planar, diamagnetic (S = 0) and
tetrahedral, paramagnetic (S = 1) "allogons".42 Non-allogonic spin crossover is possible
for d8 Ni2+ ions by axial modulation of a tetragonal ligand field, wherein the eg orbital
degeneracy is lifted.83-90 Dynamic ligand-field rearrangements are difficult to engineer in
the solid state. However, the anomalous magnetism of a few penta- and hexacoordinate
Ni2+ complexes has long been attributed to spin isomerism;83,91-98 although the relevant
spin isomers were not structurally characterized.
In the present work, we obtained
structural and magnetic data that support solid-state, non-allogonic spin crossover of
pentacoordinate Ni2+ in a bio-inspired N3S2 ligand field.
The inspiration for our investigation is a nickel-dependent superoxide dismutase,
recently structurally characterized as a mixture of oxidized Ni3+ in a square pyramidal
N3S2 ligand field including the N-terminal amine, the adjacent backbone amide, Cys-2
and -6 thiolates, and an axial His-1 imidazole, as well as reduced Ni2+ in a square-planar
85
N2S2 ligand field with a detached imidazole.7,8 Retention of the latter axial ligand in a
catalytic NiSODred intermediate would give square pyramidal d8 spin isomers, either
elongated and diamagnetic (S = 0), or compressed and paramagnetic (S = 1), depending
on the strength of the interaction.9,16 NiSODred might therefore exhibit non-allogonic spin
crossover.
We
have
reported
Ni2+
complexes
of
the
facially
tridentate
hydrotrispyrazolylborate chelates (hydrotris-3-R′-5-methyl-1-pyrazolylborate: R′ = Me,
TpMe,Me; R′ = Ph, TpPh,Me) with zwitterionic dithiocarbamate (R2NCS2-; R = Et, Ph) coligands as models for the biologically unique active site of NiSODred.36,37 In solution,
these synthetic complexes exhibit a k3-/k2-scorpionate equilibration between a green
paramagnetic N3S2 allogon, and a red diamagnetic N2S2 allogon with a detached
pyrazolyl donor. Analogous spin equilibrium driven by cyclopatadienyl ring distortion in
solution was observed in Cp*Ni(acac).59
In the solid state, sterically unhindered
TpMe,MeNiS2CNEt2 crystallized as a green, square-pyramidal k3-allogon with trigonal
distortion (τ = 0.31),37 while bulkier TpPh,MeNiS2CNR2 (R = Et, Ph) complexes
crystallized as red square-planar k2-allogons (τ = 0.01).36
In the present work, we
prepared the complex TpPh,MeNiS2CNMe2 of intermediate bulk, and isolated a green
crystalline solid at room temperature. This material exhibits non-allogonic spin crossover
in the solid state.
Two structure determinations were performed on separate crystals at 293 K (JLP)
and 123 K (VGY). Crystal data are summarized in Table 10, and coordinate bond
lengths are given in Table 11. Essentially identical triclinic P-1 lattices were observed at
86
both temperatures (Table 10 and Figure 21), with 1.0-1.5 % contractions in the unit cell
axes and a 3.1 % reduction in unit cell volume at the lower temperature. The lattices
contained two crystallographically independent TpPh,MeNiS2CNMe2 molecules (i.e., Ni1
and Ni2, Figure 22), both pentacoordinate and approximately square pyramidal (τ = 0.28
and 0.32 for Ni1 and Ni2, respectively).
Consistent with the green color of the complexes, the coordinate bond lengths of
the Ni1 site are suggestive of high-spin Ni2+ (Table 11). The overall structure at this site
compares well with that of the TpMe,MeNiS2CNEt2 analogue,37 previously demonstrated to
be purely high-spin in the solid state by measurement of magnetic susceptibility.96 At
293 K, the Ni1 complex displays an axial H-B1-N2-N1 torsion angle of 179.6(2)º and a
short apical bond length of 2.048(1) Å (Ni1-N1), while the equatorial Ni-N and Ni-S
bond lengths are significantly lengthened compared to red k2-TpPh,MeNiS2CNEt2.36
Trigonal distortion is evident along the N3-Ni1-S1 bond axis of 172.10(4)º in the
equatorial plane, and slight disparities between the two Ni-N and Ni-S equatorial bond
lengths are observed. The structure of the Ni1 complex is essentially invariant at 123 K.
All these results are consistent with single-electron occupation of both the axial and
equatorial dσ* orbitals in a high-spin (S = 1) d8 electron configuration.
Compared to Ni1, the Ni2 site displays a somewhat longer apical Ni-N bond
length of 2.149(1) Å at 293 K, with a decreased H-B2-N9-N11 torsion angle of 167.2(2)º.
A modest yet significant shortening of the equatorial Ni-N and Ni-S bond lengths is also
apparent (Table 11). This suggests the Ni2 site represents a superposition of high- and
low-spin isomers. While the Ni1 site is invariant at 123 K (Table 11 and Figure 22), the
87
axial bond length at the Ni2 site increases to 2.401(2) Å, with a further decrease of the HB-N-N torsion angle to 163.5(2)º and the τ value to 0.22. Contractions of the equatorial
Ni-N and Ni-S bond lengths are also observed. High-spin fractions at the Ni2 site can be
estimated from observed equatorial bond lengths, taking the averaged Ni1 values as the
high-spin limit and square planar TpPh,MeNiS2CNEt2 as the low-spin limit (Table 11).
Linear interpolations between these values give average high-spin fractions of 38 ± 2 %
at 123 K and 87 ± 5 % at 293 K. Back extrapolation of a limiting Ni-N axial bond length
for a low-spin square pyramid gives a value of 2.62 Å from the 123 K dataset. For
comparison, values of 1.958 and 2.612 Å were calculated by DFT for the axial NiN(His1) bonds of the respective low- and high-spin isomers of square-pyramidal
NiSODred.9
The structural data also yield insight into the mechanism of selective spin
crossover at the Ni2 site.
The equatorial ligand plane of the crossover-active Ni2
complex is oriented with the uniquely long unit cell c axis, while that of the inert Ni1
complex is nearly orthogonal (Figure 21). Temperature-dependent lattice contraction
would thus place particular pressure on the equatorial ligands of Ni2, driving the
crossover.
A short van der Waals contact between a methyl substituent on the
dithiocarbamate ligand of Ni2 and the proximal equatorial pyrazole of Ni1 may serve to
enhance this effect. Corresponding axial elongation is accommodated by displacement of
the nickel atom, rather than the axial donor, within the pocket circumscribed by the 3-Ph
substituents. The thermal ellipsoid of Ni2 thus exhibits high eccentricity at 123 K, with
the major axis nearly aligned with the apical Ni2-N8 bond vector (Figure 22). An
88
intermolecular π-stacking interaction is also observed between one equatorial pyrazole
ring (i.e., N10) on two separate Ni2 complexes related by crystallographic inversion, with
a rigorously coplanar separation of 3.685 at 293 K and 3.652 Å at 123 K.
Magnetic susceptibility data were obtained for TpPh,MeNiS2CNMe2 in the solid
state from 300 K down to 5.0 K (Figure 23).
Similar measurements for
TpMe,MeNiS2COMe gave no evidence of spin crossover; the data were fit to the Curie Law
with χT = 1.42 emu-K/mole (µ = 3.37 µB), Θ = -6.1 K, consistent with an S = 1 ground
state and second-order spin coupling.37 Comparable magnetic susceptibility is observed
in the present work at the high-temperature limit, χT = 1.40 emu-K/mole (µ = 3.35 µB) at
300 K, but the magnetization decreases with decreasing temperature, dropping by half at
70 K. This is consistent with spin crossover of one-half of the Ni(II) sites (i.e., Ni2) to an
S = 0 state. The magnetization data were fit to Maxwell-Boltzmann statistics over the
range of 100-300K (Figure 23),99 yielding: ∆Hº = 1.1(1) kcal/mole, ∆Sº = +7.3(1)
cal/moleK; ∆Gº293K = -360 cm-1 ; t1/2 = 151 K. Systematic curvature was retained in the
optimized van't Hoff plot, suggesting weak coupling of the crossover to lattice effects in
the manner already described.
Combined with the consequent ligand field
rearrangement, this may lead to departure of the crossover entropy from the inherent
spin-only value (i.e., R•ln3 = +2.2 cal/moleK).91
Temperatures below 100 K result in further loss of paramagnetism, indicating
subsequent crossover of high-spin Ni2+ remaining at the Ni1 site. Given coincident
effects expected from zero-field splitting and antiferromagnetic coupling, these data were
excluded from the fit. Nevertheless, a selective, two-step spin crossover arising from
89
crystallographically independent Ni2+ sites is demonstrated. Such a phenomenon has
been documented for a handful of octahedral Fe2+ complexes.100
Compared to t2g → eg electron promotion in d4-d7 ions, the origin of spin
crossover of d8 Ni2+ ions is unique, arising from loss of eg orbital degeneracy under
reduction of Oh symmetry. Since both relevant orbitals possess M-L σ* character in the
latter case, ligand field control over the crossover may be facilitated, especially given the
large offsetting axial and equatorial bond length changes observed at the Ni2 site in the
present work. The N3S2 donor set of the biomimetic ligand field may particularly favor
spin crossover,86 both in the synthetic complexes and perhaps in the reduced NiSOD
active site as well.9,16 We are exploiting the unique properties of high-spin Ni2+ to design
new complexes to support an abrupt spin transition, which will require enhanced
coupling of lattice and ligand field effects.79-82
90
Figure 21. Unit cell of TpPh,MeNiS2CNMe2 at 293 K. The spin-isomeric Ni2 complexes
are disposed to the outside left and right, and the Ni1 sites are at the center.
Figure 22. ORTEP plots of TpPh,MeNiS2CNMe2 at 293 K (left column, 30% ellipsoids),
at 123 K (center column, 50% ellipsoids) and overlays of the Ni1 and Ni2 structures at
the two temperatures (right column, least-squares alignments of B1/N4/N6 and
B2/N11/N13).
91
Figure 23. Solid-state temperature-dependent magnetic susceptibility data (χT, left axis;
1/χ, right axis) for TpPh,MeNiS2CNMe2. Dashed lines are maximal Curie Law slopes for
inverse susceptibility (i.e., T = C/χ, ●, right axis) at 50% and 100% mole fractions of
high-spin Ni2+. Solid curves are the calculated Maxwell-Boltzmann fit to spin crossover
of Ni2 (see text). The discontinuity near 54 K is assigned to adventitious O2.
92
Table
10.
Summary
of
the
X-ray
crystal
structure
determinations
TpPh,MeNiS2CNMe2.
Temperature
293(2) K
123(2) K
Empirical formula
C33H34BN7NiS2
C33H34BN7NiS2
Formula weight
662.31
662.31
Crystal system
triclinic
triclinic
Space Group
P-1
P-1
a, Å
12.1442(8)
12.004(1)
b, Å
12.6611(9)
12.536(1)
c, Å
25.058(2)
24.678(2)
α, deg.
90.556(1)
91.034(1)
β, deg
102.356(1)
101.353(1)
116.994(1)
116.788(1)
3328.3(4)
3225.9(5)
4
4
Density (calc), g/cm
1.322
1.364
Absorption coefficient (cm-1)
7.43
7.66
Reflections
23405
38246
Independent (Rint)
14697 (0.0325)
14519 (0.0282)
Data/restraints/parameters
14697/1/849
14519/0/803
R1 [I > 2σ(I)]
0.0500
0.0373
wR2 [I > 2σ(I)]
0.1373
0.0849
R1 (all data)
0.0632
0.0525
wR2 (all data)
0.1496
0.0934
1.029
1.040
1.344, -1.030
0.548, -1.473
γ, deg
3
Volume, Å
Z
3
Goodness-of-fit (GOF)
3
Difference peak, hole (e/Å )
for
Table 11. Summary of ligand field bond lengths and geometry.
TpMe,MeNiS2CNEt2
TpPh,MeNiS2CNMe2 TpPh,MeNiS2CNMe2 TpPh,MeNiS2CNMe2 TpPh,MeNiS2CNMe2 TpPh,MeNiS2CNEt2
(b)
[Ni1], 293 K
[Ni1], 293 K
[Ni1], 123 K
[Ni2], 293 K
[Ni2], 123 K
[Ni1],(c) 293 K
Ni-Nax,eq, Å (a)
2.027(1) [N1]
2.048(1) [N1]
2.038(2) [N1]
2.149(1) [N8]
2.401(2) [N8]
2.805(1) [N6]
Ni-Neq,ax
2.065(1) [N3]
2.111(1) [N3]
2.111(2) [N3]
2.083(1) [N12]
2.003(2) [N12]
1.934(1) [N3]
Ni-Neq,eq
2.063(1) [N5]
2.058(1) [N5]
2.048(2) [N5]
2.046(1) [N10]
1.972(2) [N10]
1.929(1) [N1]
Ni-Seq,eq
2.3747(8) [S1]
2.3435(5) [S2]
2.342(1) [S2]
2.3234(6) [S4]
2.257(1) [S4]
2.199(1) [S1]
Ni-Seq,ax
2.4099(7) [S2]
2.3929(5) [S1]
2.401(1) [S1]
2.3614(5) [S3]
2.272(1) [S3]
2.193(1) [S2]
H-B-N-Nax, deg
176.0(2)
179.6(2)
179.9(2)
167.2(2)
163.5(2)
133.2(2)
b
0.31
0.28
0.29
0.32
0.22
0.01
τ
(a) first position listed refers to the primary square pyramidal geometry, second to the minor trigonal distortion. (b) reference 37. (c) reference 36.
CHAPTER VI: PROTONATION OF MODEL COMPLEXES
Compared to less bulky TpMe,MeNi2+ complexes that yield only 5-coordinate high
spin trigonal bipyramidal species in the solid state,37 the bulkier TpPh,MeNi2+ complexes
showed distinct spin-dependent structures.36,38
Isomers of the same chemical
composition (i.e., 5 and 6) formed different k2-scorpionate low spin square planar Ni2+
structures, characterized at 293 K and 173 K, respectively (Figure 7 and Figure 24).
Selected bond lengths and angles are listed in Table 12. Equatorial Ni-N bond
lengths are 1.929 Å (Ni1-N1) and 1.934 Å (Ni1-N3) in complex 5 vs 1.915 Å (Ni1-N6)
and 1.921 Å (Ni1-N2) in complex 6. Equatorial Ni-S bond lengths are 2.199 Å (Ni1-S1)
and 2.193 Å (Ni1-S2) in complex 5 vs 2.204 Å (Ni1-S1) and 2.197 Å (Ni1-S2) in
complex 6. In both 5 and 6, Ni-N and Ni-S bond lengths compare well within about 0.01
Å difference, which are comparable to reported square planar Ni2+N2S2 values.34,101-105
Also, these Ni-N and Ni-S bond lengths compare well with bond lengths in reduced
NiSOD, either calculated by DFT,4,9,16 or observed by X-crystallography.7,8
Interestingly, distances between the detached axial pyrazol nitrogen and nickel are
2.805 Å (Ni1•••N6) in complex 5 vs 3.002 Å (Ni1•••N4) in complex 6, a difference of
0.197 Å. In contrast, the average basal bond angles70 (N1-Ni1-S1 and N3-Ni1-S2 in 5;
N2-Ni1-S2 and N6-Ni1-S1 in 6) are 172.66º and 173.64º respectively. The flatter average
basal angle yields a longer Ni•••N distance. Morever, the average C-S bond lengths are
1.708 Å in complex 5 and 1.713 Å in complex 6. Bite angles of k2-scorpionate ligand are
90.32º (N1-Ni1-N3) in 5 and 90.81º (N2-Ni1-N6) in 6; meanwhile, bite angles of k2S,S’dithiocarbamate are 78.06º (S1-Ni1-S2) in 5 and 78.46º (S1-Ni1-S2) in 6. An
increase of 0.49º of N-Ni-N angles upon an increas of 0.40º of S-Ni-S angles associates
95
with the trend of decreasing of bond angles C-S-Ni by an average of 86.71º (C31-S1-Ni1
and C31-S2-Ni1 in 5) to 86.21º (C31-S1-Ni1 and C31-S2-Ni1 in 6). Upon changing the
temperature from 293 K to 173 K, chelating bite angles were both increased without
dramatic bond lengths change to obtain a compressed NiN2S2 plane with a more “pushed
away” axial pyrazole. This movement indicates equatorial bond lengths are fairly rigid
but the detached pyrazole “arm” is quite flexible.
Complex 8 was characterized at 173 K (Figure 25 and Table 12), the same as 6,
but formed a 5-coordinate high spin k3-scorpionate trigonal bipyramidal NiN3S2 (τ =
0.61), instead of a 4-coordinate low spin k2-scorpionate square planar NiN2S2. In complex
8, equatorial bond lengths of Ni-N are 2.040 Å (Ni1-N4) and 2.079 Å (Ni1-N6), at least
0.10 Å longer than Ni-N bond lengths in 5, 6 and 7. The equatorial Ni1-S1 is also longer
than in corresponding complexes by about 0.14 Å. The axial bond lengths of Ni-N and
Ni-S are 2.106 Å (Ni1-N2) and 2.421 Å (Ni1-S2). The dramatic elongated axial bond
length causes the dz2 orbital to drop to a lower energy level, forming high spin 2:1:2
ligand field splitting, compared to low spin 2:2:1 d orbital splitting in 5, 6 and 7.
Compared to typical trigonal bipyramidal Ni2+N3S2 complexes, the equatorial Ni-N bond
lengths are about 0.10 Å longer than 1.936 Å, 1.974 Å, 1.968 Å, with similar differences
for equatorial Ni-S bond lengths106,107. The difference is that 8 forms an NNS equatorial
plane but the examples are comprised of NSS equatorial donors. The S1-Ni1-S2 bite
angle decreased by about 3º compared to corresponding angles in 5, 6 and 7;
displacement along S1-C31-S2 away from the nickel center lets the pyrazole N donor
arm gain more space to access the nickel center. The approaching pyrazole ring pushes
96
the chelating dithiocarbamate, twisting the equatorial plane from cis to trans connecting
nickel. The bond length of C31-S1, 1.721 Å is longer than C31-S2, 1.690 Å; equatorial
S1 has a stronger contact with Ni1 than the axial S2.
97
Figure 24. Perspective view of the molecular structure of the low-temperature polymorph
complex 6, Polymorph-LT-TpPh,MeNiS2 CNEt2, with the atom labeling scheme.
98
Figure 25. Perspective view of the molecular structure of complex 8, green
TpPh,MeNiS2CNPh2, with the atom labeling scheme.
99
Table 12. Selected bond lengths (Å) and angles (º) for complexes 6 and 8.
Complex 6
Ni(1)-N(6)
1.9153(19)
Ni(1)-N(2)
1.921(2)
Ni(1)-S(2)
2.1968(7)
Ni(1)-S(1)
2.2041(7)
S(1)-C(31)
1.714(2)
S(2)-C(31)
1.712(2)
C(31)-N(7)
1.313(3)
N(6)-Ni(1)-N(2)
90.81(8)
N(6)-Ni(1)-S(2)
94.49(6)
N(2)-Ni(1)-S(2)
174.67(6)
N(6)-Ni(1)-S(1)
172.61(6)
N(2)-Ni(1)-S(1)
96.26(6)
S(2)-Ni(1)-S(1)
78.46(2)
C(31)-S(1)-Ni(1)
86.07(8)
C(31)-S(2)-Ni(1)
86.34(8)
Ni(1)-N(4)
2.0401(16)
Ni(1)-N(6)
2.0794(17)
Ni(1)-N(2)
2.1066(17)
Ni(1)-S(1)
2.3410(6)
Ni(1)-S(2)
2.4210(6)
S(1)-C(31)
1.721(2)
S(2)-C(31)
1.690(2)
C(31)-N(7)
1.351(3)
N(4)-Ni(1)-N(6)
96.34(6)
N(4)-Ni(1)-N(2)
87.68(7)
N(6)-Ni(1)-N(2)
87.05(7)
N(4)-Ni(1)-S(1)
124.11(5)
N(6)-Ni(1)-S(1)
138.93(5)
N(2)-Ni(1)-S(1)
100.20(5)
N(4)-Ni(1)-S(2)
94.67(5)
N(6)-Ni(1)-S(2)
96.72(5)
N(2)-Ni(1)-S(2)
175.30(5)
S(1)-Ni(1)-S(2)
75.12(2)
C(31)-S(1)-Ni(1)
84.90(7)
C(31)-S(2)-Ni(1)
83.03(7)
Complex 8
100
The axial N donor equilibrium in our model complexes may also exist at the real
NiSOD redox active site. Also, the position of protonation needs to be determined. Two
mechanistic hypotheses involve protonated axial N or equatorial S donor atoms.7,16-18
Since our model complexes display an axial N 4-/5-coordinate equilibrium in solution,
we conclude that energy barriers between two isomers should be quite small.
Thermodynamic and titration experiments were conducted to quantify the equilibrium
behavior and protonation. Results for 7 in CH3CN were discussed in chapter III.
A crystal structure for an axial N-protonated axial complex was not obtained.
Instead, addition of one equivalent trifluroacidic acid to green 7/8 solutions gave
decomposition products red 13 and green 14. In 13, the axial pyrazole was substituted at
boron by one trifluoroacetate anion CF3COO-, and in 14, the equatorial dithiocarbamate
was displaced by free pyrazole and one trifluroacidic acid group (Figure 26 and Figure
27). Selected bond lengths and angles are listed in Table 13. This indicates a complicated
decomposition sequence: the axial N was first protonated; then the CF3COO- conjugate
base displaced the protonated pyrazole on boron to yield 13 and free pyrazole; then the
pyrazole binds to a second molecule; the proton on axial N migrates to one equatorial S;
finally, the CF3COO- anion binds to Ni to displace protonated dithiocarbamate and obtain
14.
Complex 13 thus forms a “tail-cut” k2-scorpionate low spin square planar
Ni2+N2S2 at 293 K. Compared to square planar complex 7, with equatorial Ni-N bond
lengths of 1.910 Å (Ni1-N1) and 1.911 Å (Ni1-N3), and Ni-S bond lengths of 2.183 Å
(Ni1-S2) and 2.201Å (Ni-S1), Ni-N bond lengths in 13 are 1.908 Å (Ni1-N1), 1.916 Å
101
(Ni1-N3), and Ni-S bond lengths 2.192 Å (Ni1-S2), 2.204 Å (Ni1-S1). These bond
lengths are therefore typical square planar values.34,101-105 The distance between detached
N and Ni in complex 7 is 3.541 Å (Ni1•••N6), the distance between detached O and Ni
center is 4.516 Å (Ni1•••O2) in complex 13. Interestingly, the average basal bond angle
N-Ni-S is 171.01º in 13 with almost the same value 171.00º in 7. Both comparable bond
lengths and average basal angles in 7 and 13 indicated that geometrical properties of
square planar NiN2S2 were not dramatically affected by substitution of the CF3COO anion. Morever, the average C-S bond length is 1.706 Å comparable to 1.703 Å in 7. As
expected, a similar bond length C(23)-N(5) 1.331 Å in 13 also comparable to C(31)-N(7)
1.333 Å appeared in 7. The bite angle of the k2-scorpionate ligand is 90.53º (N1-Ni-N3)
in 13, compare well with 90.34º (N1-Ni1-N3) in 7; meanwhile, bite angles of the k2-S,S’dithiocarbamate are 78.73º (S1-Ni1-S2) in 13 and 78.84º (S1-Ni1-S2) in 7. In all,
comparison of complexes 7 and 13 indicates that as long as the axial donor is far enough
away from Ni center, either N or O will not affect d orbital splitting pattern. Until the
distance falls into an appreciate range, then the splitting changes from 2:2:1 to 2:1:1:1 to
2:1:2 among 10, 11 and 8.
Complex 14 occupies a square pyramidal geometry with the axial N donor from
k3-scorpionate N3 tripodal ligand. The other two scorpionate N donors are associated
with the square plane, along with one trifluoroacetate O donor and one N donor from free
3-phenyl-5-methylpyrazole. The axial Ni1-N1 bond in 14, 2.037 Å is comparable to
other axial Ni-N bond lengths in our square pyramidal model complexes: 2.052 Å in 9;
2.038 Å in 11; and 2.048 Å in 12, despite different ligand fields, N3ON in 14 from N3S2
102
in 9, 11 and 12. Equatorial Ni-N bond lengths, 2.081 Å in 14, 2.070 Å (Ni1-N3) and
2.092 Å (Ni1-N5), are also comparable to 2.060 Å in 9, 2.080 Å in 11 and 2.085 Å in 12.
The average basal angle between N3-Ni1-O1 and N5-Ni1-N7 in 14 is 165.74º, which is
also comparable to average basal angles N-Ni-S 162.40º in 9, 164.09º in 11 and 163.78º
in 12. Equatorial bite angles for N-Ni-N and O-Ni-N(pz) are 85.25º and 94.84º in 14,
respectively. Equatorial bite angles for N-Ni-N and S-Ni-S are 87.54º and 74.75º in 9;
84.13º and 75.43º in 11; 84.31º and 75.18º in 12. Constrained N-Ni-N bite angles did not
change much even in the different ligand field of 14; however, a dramatic bite angle
increased by about 20º for O-Ni-N(pz) in 14 compared to other competitive S-Ni-S
angles in 9, 11 and 12. The big differences are the flexibility of two coordinated
equatorial ligands, pyrazole and trifluoroacidic acid, which can freely move in contrast to
constrained chelating S,S’-dithiocarbamates, and substitution of O and N donors for two
S donors. Actually, in the active NiSOD enzyme, two S donors from different Cys2 and
Cys6 have flexible coordination modes, also.7,8 Complex 14 provided more information
about the coordination environment change by switching chelating ligands to two
independent donors, which still can form a square pyramidal geometry.
These results give some insights into modeling the NiSOD active site. One,
tripodal N donors like k3-scorpionate ligand are able to form different geometries relevant
to structural change in reduced NiSOD; secondly, the k3-scorpionate ligand is rigid in a
specific geometry like a square pyramid, including coordination modes, bond lengths and
angles even in different ligand fields, which is important to study transition states during
a model NiSOD catalytic cycle; finally, flexible independent thiolates that mimic two
103
equatorial sulfur donors in a square pyramidal complex will be closer to modeling sulfur
donors in NiSOD system.
104
Figure 26. Perspective view of the molecular structure of complex 13
(CF3COO)BpPh,MeNiS2CNPh2 with the atom labeling scheme. The perfluoromethyl
group exhibits a two-site conformational disorder. The thermal ellipsoids are scaled to
enclose 30% probability.
105
Figure 27. Perspective view of the molecular structure of complex 14
TpPh,MeNi(pz)(OOCCF3) with the atom labeling scheme. The dashed line shows the
presence of an intramolecular N-H···O bond. The thermal ellipsoids are scaled to
enclose 30% probability.
106
Table 13. Selected bond lengths (Å) and angles (º) for complexes 13 and 14.
Complex 13
Ni(1)-N(1)
1.908(2)
Ni(1)-N(3)
1.916(2)
Ni(1)-S(2)
2.1916(6)
Ni(1)-S(1)
2.2040(6)
S(1)-C(23)
1.705(2)
S(2)-C(23)
1.706(2)
F(1)-C(22)
1.288(7)
F(2)-C(22)
1.304(5)
F(3)-C(22)
1.301(6)
F(1')-C(22)
1.271(7)
F(2')-C(22)
1.311(8)
F(3')-C(22)
1.288(7)
O(1)-C(21)
1.301(3)
O(1)-B(1)
1.510(3)
O(2)-C(21)
1.196(4)
N(5)-C(23)
1.331(3)
N(1)-Ni(1)-N(3)
90.53(7)
N(1)-Ni(1)-S(2)
93.41(5)
N(3)-Ni(1)-S(2)
170.98(5)
N(1)-Ni(1)-S(1)
171.03(6)
N(3)-Ni(1)-S(1)
96.66(5)
S(2)-Ni(1)-S(1)
78.73(2)
C(23)-S(1)-Ni(1)
85.25(7)
C(23)-S(2)-Ni(1)
85.61(8)
C(21)-O(1)-B(1)
120.1(2)
O(2)-C(21)-O(1)
128.4(3)
O(2)-C(21)-C(22)
119.5(3)
O(1)-C(21)-C(22)
112.2(3)
Ni(1)-N(1)
2.037(2)
Ni(1)-O(1)
2.047(2)
Ni(1)-N(7)
2.055(2)
Ni(1)-N(3)
2.070(2)
Ni(1)-N(5)
2.092(2)
O(1)-C(41)
1.254(3)
O(2)-C(41)
1.222(3)
N(1)-Ni(1)-O(1)
103.69(7)
N(1)-Ni(1)-N(7)
95.41(7)
O(1)-Ni(1)-N(7)
94.84(6)
N(1)-Ni(1)-N(3)
94.31(7)
O(1)-Ni(1)-N(3)
160.67(7)
N(7)-Ni(1)-N(3)
90.39(7)
N(1)-Ni(1)-N(5)
92.98(7)
O(1)-Ni(1)-N(5)
86.78(6)
N(7)-Ni(1)-N(5)
170.81(6)
N(3)-Ni(1)-N(5)
85.25(6)
C(41)-O(1)-Ni(1)
135.88(16)
N(8)-N(7)-Ni(1)
120.86(12)
O(2)-C(41)-O(1)
130.0(2)
O(2)-C(41)-C(42)
115.9(2)
O(1)-C(41)-C(42)
114.1(2)
Complex 14
107
The real NiSOD enzyme possibly involves axial N protonation process during the
catalytical cycle.7,8,16 Coincidently, our model complexes also demonstrated a protondependent coordination equilibrium. 1H NMR spectra measured before and after adding
one equivalent CF3COOH indicated the axial N was protonated (Figure 28, Scheme 8).
Diamagnetic spectra indicated the formation of square planar Ni2+N2S2 with a dissociated
and N-protonated pyrazole. Two set of protons for dissociated and associated pyrazoles
are labeled in Scheme 8. Chemical shifts for 4-H (# 4 and 4’) and 5-Me (#5 and 5’) are
1.88, 2.84 ppm and 6.26, 6.62 ppm, respectively in axial N protonated TpPh,MeNiS2CNEt2.
Two intense sharp peaks at 2.58 and 0.61 ppm were assigned for NCH2 and NCH2CH3,
respectively.108 Chemical shifts for protons on 3-Ph (#3 and 3’) fall in the range 7.34-7.78
ppm. Chemical shifts for axial N protonated TpPh,MeNiS2CNPh2 were assigned and
appeared at around similar positions (Figure 28).
108
Figure 28. 1H NMR spectra (CDCl3, 295 K) of TpPh,MeNiS2CNEt2, TpPh,MeNiS2CNPh2
and corresponding protonated by CF3COOH, respectively.
109
N
N
C
C
S
S
3
R
2+
N H+
4
N
5
Ni
N
R
R
3'
3
R
2+
N H+
N
4'
N N
B
H
S
S
4
N
R=Ph
5'
5
Ni
N
R
R
N
4'
N N
B
H
3'
R=Ph
5'
Scheme 8. Protonated H+-TpPh,MeNiS2CNEt2 (left) and H+-TpPh,MeNiS2CNPh2 (right).
110
Redox chemistry can either involve metal ions or ccordinated organic ligands,
which can lead to considerable debate while probing electrochemical properties on
organometallic complexes. Ligand-based oxidation chemistry can occur in homoleptic N
or S donor sets, and in heteroleptic ligand fields (e.g., N/P, N/O, N/S, etc.).109-117
Consequently, the issue of noninnocent ligands is widely studied.118-122. Also, metalcentered reduction123-133 and oxidation134-157 can be obtained. Not surprisingly, metalcentered redox chemistry can be observed in nitrogen-rich coordination environments,140145
sulfur-rich ligand fields153-157, heteroleptic N/O ligand sets,148-152, and also for metal
ions such as cobalt and iron.136-139
reported.134,135,146,147
In addition, di-Ni3+ complexes were also
The extensively studied redox chemistry, either in chemical
oxidation or bulk electrolysis, suggests high valent oxidative metal ions can be unstable
even at quite low temperature, the lifetimes claimed were only for a brief period in some
above mentioned examples.
Although it is a synthetic challenge to isolate Ni3+ complexes, the possibility still
attracts people to study this chemistry. In nature, for example, the kobs = 2 x 109 M-1·S-1
is for turnover rate of Ni2+/Ni3+ in NiSOD.6
A key to modeling the fast catalytic
mechanism in NiSOD is to confirm that synthetic complexes could be oxidized and
reduced at nickel center, even for short periods within the timescale of employed probing
instruments and methods. Then, one can follow the critical conditions to mimic possible
pathways and determine corresponding reaction rates.
If necessary, fine tuning of
properties such as solubility, redox potential, hydrogen bonding networks, and etc. can
111
closely approach the native environment. Guided by above principles, we successfully
obtained our structurally modeling complexes discussed in previous chapters.
Complex 18 was obtained through reaction with AgBF4 in CH3CN and
recrystallized from THF/Et2O at -33ºC.
Instead of obtaining an oxidized Ni3+N3S2
complex, we obtained a ligand substituted Ni2+ complex.
This again indicates that
chelating S,S’-dithiocarbamates can be displaced, as previously discussed for complex
14. The structure determination of 18 (Figure 29) was of poor quality. However, it
occupies a square pyramidal geometry (τ = 0.37) with an axial N donor from the k3scorpionate N3 tripodal ligand; two equatorial scorpionate N donors, one solvent
tetrahydrofuran O donor and one solvent acetonitrile N donor form the square pyramidal
basal plane. Selected bond lengths and angles are listed in Table 14. The axial 2.034 Å
(Ni1-N4) in 18 is comparable to the axial 2.037 Å (Ni1-N1) in 14 within the similar
N3ON ligand fields in 14 and 18. The average equatorial Ni-N bond length of 2.036 Å in
18 (2.030 Å N6-Ni1 and 2.041 Å N2-Ni1) is also comparable to average equatorial Ni-N
bond length 2.081 Å in 14 (2.070 Å Ni1-N3 and 2.092 Å Ni1-N5). The average basal
angle between N2-Ni1-O1 and N6-Ni1-N7 in 18 is 165.30º, which is also comparable to
average basal angle 165.74º between N3-Ni1-O1 and N5-Ni1-N7 in 14. Equatorial bite
angles for N2-Ni1-N6 and O1-Ni1-N7 are 84.85º and 87.92º in 18, respectively and
equatorial bite angles for N3-Ni1-N5 and O1-Ni1-N7 are 85.25º and 94.84º in 14. It was
not a surprise to see constrained bite angles N-Ni-N did not change much in a different
ligand field in 18. Reasons for this trend were discussed already for complex 14. There
are two flexible coordinated equatorial solvent ligands THF and CH3CN in 18, and
112
substituted pyrazole and trifluoroacetic acid positions in 14. Except for these small
ligands freely moving around in contrast to other discussed constrained chelating S,S’dithiocarbamates, 18 is the only positive charged complex among our model complexes
since others are all neutral.36-38
The big difference between 14 and 18 is the former added trifluoroacetic acid,
while the later one was treated with Ag+, which can be considered as a weak Lewis acid.
The mechanism to obtain 18 is S,S’-dithiocarbamate transmetalation to form a Ag+
dithiocarbamato complex, with two or three CH3CN solvent molecules coordinating to
Ni2+. During recrystallization, one THF solvent molecule displaced all but one CH3CN
to finally form 18. So, AgBF4 played a role other than an oxidant in this reaction. One
can conclude that for sulfur rich ligand fields, soft Lewis acidic metal ions should be
avoided. S,S’-dithiocarbamate has a tendency to bind protons based on 14 and Lewis
acids based on 18, which is another indirect evidence for proton migration to equatorial S
donors. So, in acid-free oxidation conditions, we can expect our model complexes to be
oxidized with axial N coordinated. For such reactions, it may be possible to obtain
Ni3+N3S2, provided there is an opportunity to form a stable small molecule byproduct like
H2O2 and O2 in the NiSOD catalytic cycle.7,8
The chemical oxidation of our Ni2+N3S2 models was not quite successful so far,
but the data obtained still supply useful tips for further study of this issue. Comparing 5,
14 and 18, one can conclude that in a less electron rich coordination environment, it is
more likely to form k3-five coordinated complex except for dramatic steric effects which
is also true in our other model complexes discussed before. Based on these above
113
conclusions, one can see why square pyramidal Ni3+N3S2 exists in the oxidized NiSOD
enzyme. Furthermore, it seems less likely to form square pyramidal Ni2+N3S2 for reduced
NiSOD. In the real NiSOD enzyme, the axial N donor should prefer to bind oxidized
Ni3+N2S2 to stabilize Ni3+, rather than reduced Ni2+N2S2. But, the kinetic barrier for
quick turnover of Ni2+/Ni3+ couple may require retention of the axial N to tune the
Ni2+/Ni3+ redox potentials to mild conditions. The reduced NiSOD may be axially bound,
possibly with a long axial Ni-N bond length, rather than an axially N detached square
planar geometry.
114
Figure 29. Perspective view of the molecular structure of complex 18
TpPh,MeNi(THF)(CH3CN) with the atom labeling scheme.
115
Table 14. Selected bond lengths (Å) and angles (º) for complex 18.
Complex 18
Ni(1)-N(7)
2.010(4)
Ni(1)-N(6)
2.030(4)
Ni(1)-N(4)
2.034(4)
Ni(1)-N(2)
2.041(4)
Ni(1)-O(1)
2.081(3)
N(7)-C(31)
1.138(7)
C(31)-C(32)
1.458(8)
N(7)-Ni(1)-N(6)
154.34(17)
N(7)-Ni(1)-N(4)
108.22(17)
N(6)-Ni(1)-N(4)
97.43(17)
N(7)-Ni(1)-N(2)
95.06(17)
N(6)-Ni(1)-N(2)
84.85(17)
N(4)-Ni(1)-N(2)
91.19(17)
N(7)-Ni(1)-O(1)
87.92(16)
N(6)-Ni(1)-O(1)
91.49(15)
N(4)-Ni(1)-O(1)
90.01(15)
N(2)-Ni(1)-O(1)
176.26(16)
C(31)-N(7)-Ni(1)
174.3(5)
N(7)-C(31)-C(32)
179.1(6)
116
Comparing redox potentials in both TpMe,MeNi2+ and TpPh,MeNi2+ complexes, one
can conclude E1/2 is more positive in TpMe,MeNi2+, except almost equal potentials in S,S'diphenyldithiocarbamate as the co-ligand supported by different scorpionate ligands.
Based on these obvious differences, it is possible to suggest the existence of formal Ni3+
in the model complexes on the cyclic voltammetric time scale. High-valent, formally
Ni3+ and Ni4+ complexes supported by dithiocarbamate ligands have been reported,158,159
but these frequently decompose by reductive loss of ligand radical.51 The nature of the
Ni-S covalency raises the issue of redox non-innocence of both the active site thiolates
and the synthetic chelates.105 So, the possibility of noninocent ligand redox chemistry
certainly can not be ruled out only judged by potential differences due to competitive
redox behavior and potentials in corresponding TpPh,MeCo2+ complexes (Table 6).
Chemical oxidation experiments were performed, however, not quite as expected to
obtain isolated Ni3+. Possible reaction pathways are described in Scheme 9; idealized
chemical redox reactions driven by superoxide radical are shown in Scheme 10.
Regardless, our model complexes do exhibit facile, tuneable oxidation in cyclic
voltammetry and an axial equilibrium coupled to spin crossover, which together mimic
key properties of reduced NiSOD intermediates.7-9,16
117
C
C
H+
S S
-O
H+3 R
R
R
R
Ni
N N N
N NN
B
C
Ni
N N
HO N N
B
S S
+2 R
R
N Ni
NH
N N
NN
HO B
H
H
H
+2 R
Ni
N N N
N NN
B
H
R
Ni
N N N
N NN
B
R
R
NO H2O
Oxidant
Reductant
S S
+3 R
R
Ni
N N N
N NN
B
H
H
AgBF4
H2O CH CN
3
CH
3 CN
OH
AgBF4
CH3CN
H2O
S S
+2 R
R
NR'2
NR' 2
C
C
S SH+
+2 R
Ni
N N N
N NN
B
H
S
R
R
Ag+
S
+2R
Ni
N N N
N NN
B
H
H+
R
3
Ni
N N N
N NN
B
Ag0
NR'2
C
H
R
R
R
NR'2
C
NC
C
R
H
R
R
R
CH 3
S
S S
+3 R
S
HS2CNR'2
C
S S
+2 R
NC
NR'2
+3 R
N
NH
C
AgBF4
H2O CH CN
3
NR'2
Ni
N N N
N NN
B
R
NR'2
NR'2
H
C
OH
R
S S
+2 R
Ni
NH+ N N
N NN
B
H
H+
R
NR'2
NR'2
BF4R
Ag(S2CNR'2)2
Scheme 9. Possible oxidation pathways of Ni2+ complexes.
+2 R
Ni
N N N
N NN
B
H
BF4
R
118
N
3+
Ni
S
O
O
S
O 2-
O
N
K+
O
N
O
O
S
2+
Ni
N
S
N
N
Scheme 10. Idealized Ni2+/3+ redox chemistry driven by O2· radical in modeling N3S2
ligand field.
119
CHAPTER VII: Co2+N3S2 COMPLEXES AS MODELS FOR THE OXIDIZED
Ni3+N3S2 ACTIVE SITE
High-valent Ni3+ is supported by sulfur-rich ligand fields in enzymes like NiSOD
Ni3+N3S2,7,8,19,22 Acetyl coenzyme-A Synthase Ni3+S3X (X = CO),160-162 and NiFe
hydrogenase Ni3+S4.163 As a d7 metal ion, Co2+ is isoelectronic with Ni3+. Therefore, we
prepared three Co2+N3S2 complexes by switching Ni2+ with Co2+, including
TpPh,MeCoS2CNEt2 (15), TpPh,MeCoS2CNPh2 (16), and TpPh,MeCoS2COEt (17).
All three Co2+ complexes 15, 16 and 17 are all trigonal bipyramidal (Figure 30,
Figure 31 and Figure 32), in contrast to square planar 5 (Figure 7) and square pyramidal 9
(Figure 9) but similar to trigonal bipyramidal 8 (Figure 25). The most nearly identical
structures are trigonal bipyramidal Co2+ 16 and Ni2+ 8, although the latter one was
characterized at 173 K instead of 273 K.
Complex 7, the spin isomer of 8, was
characterized at 273 K and found to be square planar (Figure 8). No k2-Tp equilibria
were expected or observed for Co2+.
Selected bond lengths and angles for Co2+ complexes are listed in Table 15.
Average equatorial Co-N bond lengths are 2.092 Å (2.083 Å Co1-N5 and 2.100 Å Co1N1 in 15), 2.089 Å (2.068 Å Co1-N1 and 2.110 Å Co1-N5 in 16) and 2.065 Å (2.063 Å
Co1-N5 and 2.067 Å Co1-N1 in 17), respectively. Equatorial Co-S bond lengths are
2.362 Å Co1-S1, 2.356 Å Co1-S1 and 2.339 Å Co1-S1 correspondingly. Meanwhile,
axial bond lengths for Co-N and Co-S are 2.196 Å (Co1-N3) and 2.426 Å (Co1-S2) in 15;
2.177 Å (Co1-N3) and 2.460 Å (Co1-S2) in 16; 2.165 Å (Co1-N3) and 2.542 Å (Co1-S2)
in 17. As expected, axial bond lengths for Co-N and Co-S are all longer than
120
corresponding average equatorial bond lengths, the differences are all about 0.10 Å for
Co-N bond lengths. However, the differences for Co-S bond lengths gradually increased
by 0.06, 0.10 and 0.20 Å. This indicated that axial Co-S bond lengths are becoming
elongated, presumably with decreasing donating abilities, from 15 to 16 and finally to 17.
Surprisingly, this trend caused all equatorial bond lengths and the other axial bond length
to dramatically decrease. The same trend was also observed in decreasing average C-S
bond lengths 1.719 Å in 15, 1.706 Å in 16 and 1.684 Å in 17. Bite angles of S-Co-S also
slightly decreased from 74.77º in 15 to 74.58º in 16 to 73.29º in 17, which followed the
decreasing bond lengths trend. The biggest steric effect in 16 led to the biggest trigonal
distortion (τ = 0.65), with the smallest distortion angle (τ = 0.54) due to the smallest
steric effect in 17.
Comparing the trigonal bipyramidal complex TpPh,MeCoS2CNPh2 (16) with
TpPh,MeNiS2CNPh2 (8) (τ = 0.65 in 16 and 0.61 in 8), one can conclude that axial bond
lengths were more affected in contrast to equatorial bond lengths within constrained N3S2
ligand field. Notwithstanding temperature differences, M-Sax/Seq bond lengths (M = Ni
and Co) from Ni-Sax/Seq (2.421/2.341 Å) to Co-Sax/Seq (2.460/2.356 Å) slightly increased
by 0.039/0.015 Å; axial M-N and average equatorial M-N bond lengths from Ni-Nax
(2.107 Å) and Ni-Neq (2.060 Å) to Co-Nax (2.177 Å) and Co-Neq (2.089 Å) increased by
0.070 and 0.029 Å, respectively. All Co-N and Co-S bond lengths in 16 are longer than
the corresponding values in 8, consistent with the bigger ionic radius of Co2+ compared to
Ni2+. However, shorter bond lengths are expected in oxidized Ni3+N3S2 complexes. The
barely changed geometry between 16 and 8 with a difference of the one electron on metal
121
ion indicates a small energy barrier to oxidation, without extra energy to rearrange the
geometry.
122
Figure 30. Perspective view of the molecular structure of complex 15 TpPh,MeCoS2CNEt2
with the atom labeling scheme. The thermal ellipsoids are scaled to enclose 30%
probability.
123
Figure 31. Perspective view of the molecular structure of complex 16 TpPh,MeCoS2CNPh2
with the atom labeling scheme. The thermal ellipsoids are scaled to enclose 30%
probability.
124
Figure 32. Perspective view of the molecular structure of complex 17 TpPh,MeCoS2COEt
with the atom labeling scheme. The thermal ellipsoids are scaled to enclose 30%
probability.
125
Table 15. Selected bond lengths (Å) and angles (º) for complexes 15, 16 and 17.
Complex 15
Co(1)-N(5)
2.083(2)
Co(1)-N(1)
2.100(2)
Co(1)-N(3)
2.196(2)
Co(1)-S(1)
2.3623(7)
Co(1)-S(2)
2.4261(8)
S(1)-C(31)
1.729(3)
S(2)-C(31)
1.709(3)
N(7)-C(31)
1.327(3)
N(5)-Co(1)-N(1)
94.09(8)
N(5)-Co(1)-N(3)
83.92(9)
N(1)-Co(1)-N(3)
88.68(8)
N(5)-Co(1)-S(1)
135.36(6)
N(1)-Co(1)-S(1)
130.23(7)
N(3)-Co(1)-S(1)
99.95(6)
N(5)-Co(1)-S(2)
97.80(7)
N(1)-Co(1)-S(2)
96.92(6)
N(3)-Co(1)-S(2)
173.99(6)
S(1)-Co(1)-S(2)
74.77(2)
C(31)-S(1)-Co(1)
85.60(9)
C(31)-S(2)-Co(1)
84.02(9)
Co(1)-N(1)
2.068(2)
Co(1)-N(5)
2.110(2)
Co(1)-N(3)
2.177(2)
Co(1)-S(1)
2.3558(6)
Co(1)-S(2)
2.4595(6)
S(2)-C(31)
1.691(2)
S(1)-C(31)
1.721(2)
N(7)-C(31)
1.356(3)
N(1)-Co(1)-N(5)
97.23(7)
N(1)-Co(1)-N(3)
86.37(7)
N(5)-Co(1)-N(3)
85.24(7)
N(1)-Co(1)-S(1)
127.21(6)
N(5)-Co(1)-S(1)
135.40(5)
N(3)-Co(1)-S(1)
99.58(5)
N(1)-Co(1)-S(2)
97.19(5)
N(5)-Co(1)-S(2)
98.85(5)
N(3)-Co(1)-S(2)
174.16(5)
S(1)-Co(1)-S(2)
74.58(2)
C(31)-S(2)-Co(1)
82.54(7)
C(31)-S(1)-Co(1)
85.17(7)
Co(1)-N(5)
2.0631(15)
Co(1)-N(1)
2.0668(14)
Co(1)-N(3)
2.1646(15)
Co(1)-S(1)
2.3385(5)
Co(1)-S(2)
2.5424(6)
S(1)-C(31)
1.697(2)
S(2)-C(31)
1.670(2)
O(1)-C(31)
1.329(2)
N(5)-Co(1)-N(1)
95.69(6)
N(5)-Co(1)-N(3)
89.94(6)
N(1)-Co(1)-N(3)
84.76(6)
N(5)-Co(1)-S(1)
123.89(4)
N(1)-Co(1)-S(1)
139.88(5)
N(3)-Co(1)-S(1)
100.11(4)
N(5)-Co(1)-S(2)
96.64(5)
N(1)-Co(1)-S(2)
98.03(4)
N(3)-Co(1)-S(2)
172.54(4)
S(1)-Co(1)-S(2)
73.29(2)
C(31)-S(1)-Co(1)
86.08(7)
C(31)-S(2)-Co(1)
80.17(8)
Complex 16
Complex 17
126
Paramagnetic electron configurations are expected for trigonal bipyramidal and
square pyramidal Ni2+ (S = 1) and Co2+ (S = 3/2) complexes. Square planar Ni2+
complexes are diamagnetic (S = 0). Since scorpionate ligands have k2/k3- coordination
modes which were demonstrated for Ni2+ in the solid state already, properties of the
complexes may be complicated due to potential coordination equilibria in solution.
Rearrangement mechanisms give rise to symmetrically simple resonances attributed to
ligands in 1H NMR spectra.164-166 Paramagnetic shifting of nuclear resonances consists of
both contact and dipolar shifts.167-171 Ground states for Ni2+ and Co2+ in octahedral ligand
fields are 3A2g and 4T1g, respectively. Anisotropy in the g-values is possible in distorted or
lower symmetry Co2+ complexes, which leads to both dipolar and contact contributions,
but contact shifts are predominant in corresponding Ni2+ complexes. The latter results
from transfer of unpaired spin density onto ligands through metal-centered σ- or πbonding molecular orbitals.165 In tetrahedral ligand fields, Ni2+ and Co2+ ground states are
3
T1 and
4
A2, and significant
anisotropy in g-values occurs only in Ni2+
complexes.164,165,169
Consistent with a paramagnetic (S = 1) ground state, Ni2+ complexes 1-4
displayed shifted resonances in 1H NMR spectra (Figure 18). Nevertheless, these are
readily interpreted given the assigned formulations. Despite the low static symmetry of
the complexes, the TpMe,Me ligand gives rise to only four resonances common in all the
spectra (Table 9), consistent with dynamic equivalence of the three pyrazole rings. Thus,
rotation of the dithioacid relative to the scorpionate face must be facile. The borohydride
and 3-methyl resonances are relatively broad and shifted somewhat upfield, while the 5-
127
methyl signal is sharper and shifted only slightly downfield. In contrast, the 4-proton
attached directly to the aromatic pyrazole ring is shifted considerably downfield. Other
resonances assignable to the organic substituents on the dithioacid chelates were also
observed. For example, an O-methyl signal was observed at 27.1 ppm in the spectrum of
1. The N,N-diethyl resonances of the dithiocarbamate complex 3 were shifted downfield
to a greater extent than the O-ethyl resonances of the xanthate complex 2, consistent with
the greater basicity of the former; corresponding attenuation of the pyrazole resonances
was also observed. These observations are consistent with a contact shift mechanism,
with significant delocalization of spin density onto the scorpionate and dithioacid ligands.
Compared with TpMe,MeNi2+ complexes, chemical shifts for substituted 3-Ph on
pyrazole ring in TpPh,MeNi2+ complexes fall in range 4-10ppm and well resolved for
ortho-, meta-, para- protons (Figure 3, Table 2), instead of broad upfield 3-Me peak. Due
to this substituted 3-Ph group, chemical shifts for 4-H on pyrazole moved upfield about
10 ppm for dithiocarbamato and 4 ppm for orgnoxanthato TpPh,MeNi2+ compared to
corresponding TpMe,MeNi2+ complexes. Chemical shifts for B-H were hardly affected with
only about 1 ppm difference as the similar difference for protons of 5-Me in two different
scorpionate ligands ligated complexes. Equivalent pyrazole proton peaks were also
observed in lower symmetry heteroscorpionate supported complexes.172-175 Meanwhile,
unequivalent magnetic resonences assigned in heteroscorpionate complexes, too.176
Magnetic moments measured by Evans NMR method support spin crossover
behavior in solution for TpPh,MeNi2+ and TpMe,MeNi2+ complexes (Table 5). For example,
µeff = 2.52µB and µeff = 2.49µB for TpPh,MeNiS2CNEt2 and TpPh,MeNiS2CNPh2,
128
respectively, obviously smaller than spin only value of 2.83µB for an S = 1 ground state.
The obtained experiment data are the average of minor S = 0 and major S = 1 spin
isomers. Larger values, µeff = 2.75µB and µeff = 2.76µB were observed for
TpMe,MeNiS2CNEt2 and TpMe,MeNiS2CNPh2. µeff = 2.71µB
was determined both in
TpMe,MeNiS2COEt and TpPh,MeNiS2COEt. This agree well with the conclusion in chapter
III, that less basic dithioacids prefer to form pentacoordinate N3S2 ligand field.
Nevertheless, a limiting value of µeff = 3.37 µB was determined for TpMe,MeNiS2COMe in
the solid state at 300 K, where axial base dissociation is blocked.
Similar paramagnetic chemical shifts were observed in both tetrahedral
TpPh,MeMCl (M = Ni2+, Co2+) (Figure 33, Table 2 and Table 16). However, the series of
1
H NMR spectra for pentacoordinate TpPh,MeCo2+ complexes (Figure 33, Table 16)
displayed significant differences compared with corresponding TpPh,MeNi2+ analogues.
The opposite shifting directions for B-H proton peaks in dithio acids added Co2+N3S2
complexes vary from the downfield range 81.9 ~ 113.8 ppm while in corresponding
Ni2+N3S2 complexes ranging upfield -8.3 ~ -9.5 ppm. Meanwhile, ortho protons on 3-Ph
in pyrazole of scorpionate ligand greatly moved to very upfield -47.8 ~ -71.1 ppm, while
the meta and para positions were nearly unshifted compared to down field shifts of 4.0 ~
4.6 ppm in Ni2+N3S2 complexes. These differences reflect dipolar contributions arising
from low-symmetry Co2+. Assuming the direction of magnetic field z axis passes through
nearly 3-fold molecular H-B-Co axis, protons falling within an angle range smaller than
54.7º off z axis will have positive downfield dipolar shifts; protons occupying a position
in a bigger angle experience an upfield shift.164
129
In all, compared with the similar geometry of TpPh,MeCo2+ and TpPh,MeNi2+
complexes in solution, one can conclude dipolar shifts greatly dominated in some certain
proton peaks such as B-H and ortho pheny protons in TpPh,MeCo2+ complexes due to the
anisotropy in the g-values in a low symmetry molecule.165,166,169 In the case of octahedral
Ni2+ occupying a 3A2g ground state and tetrahedral Co2+ with a 4A2 ground state,
significant g-value anisotropy will not be expected.165,169 Magnetic moments measured
by Evans method indicated high-spin Co2+ (S = 3/2) in solution (Table 5) consistent with
solved solid structures. The obtained experiment values are bigger than the spin only
value (3.87µB) due to spin-orbit coupling (SOC).177
130
Figure 33. 1H NMR spectra (CDCl3, 295 K) of 15-17 and TpPh,MeCoCl (bottom to top,
respectively). TpPh,MeCoS2CNEt2 (15), TpPh,MeCoS2CNPh2 (16), TpPh,MeCoS2COEt (17).
Table 16. Selected chemical shifts (ppm) for TpPh,MeCo2+ complexes in CDCl3 at 295 K.
TpPh,MeCoCl
15
16
17
B-H
-23.6
113.8
103.9
81.9
4-H
74.1
97.4
49.2
53.1
5-Me
12.4
50.6
48.7
43.3
3-Ph,meta
8.6
3.6
4.5
6.8
3-Ph,para
8.2
5.3
2.2
5.0
3-Ph,ortho
18.1
-71.1
-64.7
-47.8
131
The electronic spectra of the Co2+N3S2 complexes are shown in Figure 34. The ππ* transitions for phenyl group from 3-substituted pyrazole ring observed in Co2+
complexes share the similar range to that observed for corresponding Ni2+ complexes.
This trend is also true for 4-coordinated tetrahedral TpPh,MeMCl (M = Ni2+ and Co2+),
which indicated that π- π* transitions were hardly affected by exchanging metal ions even
in different geometries (Table 1 and Table 17). The ligand field bands in Co2+N3S2
complexes vary from 533 ~ 628nm, combining with observed extinction coefficients (ε =
0.1) suggested a 5-coordinate geometry, which compare with reported values.164 Possibly
due to more electron donating ability of -S2CNEt2 than -S2CNPh2 and -S2COEt, an
additional weak d-d transition could be identified. This difference also leads to a red shift
from 533 to 540 to 585nm, respectively. The 4-coordinate ligand field band observed in
TpPh,MeCo2+Cl ranging from 598 to 663nm are more intense and close to reported
values.164,178 Sulfur to metal charge transfer, LMCT, were observed within a narrower
range 390 ~ 401nm compared to Co2+ in a N3OS ligand field.164
Meanwhile, these series of Co2+, d7, complexes are high spin (S = 3/2) while the
oxidized native NiSOD supports a low spin Ni3+ d7 state (S = 1/2). Electron paramagnetic
resonace (EPR) spectroscopy was employed to study oxidized NiSOD, which effectively
probed geometrical and electronic configuration information at the metal center.6,7,20 The
Co2+N3S2 complexes are isoelectronic to oxidized Ni3+N3S2 complexes,. Although the
native oxidized NiSOD possesses a low spin Ni3+ (S = 1/2) while our modeling Co2+N3S2
complexes consist of a high spin Co2+ (S = 3/2), and these complexes are stable during
various instrumental time scales.
132
50
-1
ε (mM cm
-1
)
40
30
20
X 10
10
0
300
400
500
600
700
800
900
Wavelength (nm)
Figure 34. UV-Visible-NIR spectra (CH2Cl2, 295 K) of TpPh,MeCoS2CNEt2 (blue),
TpPh,MeCoS2CNPh2 (green), and TpPh,MeCoS2COEt (red).
133
Table 17. Wavelength(nm) and molar extinction coefficient (mM-1cm-1) for TpPh,MeCo2+
complexes in DCM.
CH2Cl2, λmax, nm; ε, mM-1cm-1
TpPh,MeCoCl
241; 41.2
383; 0.2
535; 0.1
598; 0.4
634; 0.6
663; 0.5
15
242; 49.9
390; 0.8
533; 0.1
628; 0.1
-
-
16
239; 36.1
288; 14.3
401; 0.7
540; 0.1
-
-
17
238; 47.2
343; 2.9
391; 0.8
585; 0.1
-
-
134
X-band, low temperature EPR spectra of 15, 16 and 17 are displayed (Figure 3537) (EPR spectra recorded by Dr. Aidan McDonald and Prof. Lawrence Que, Jr.
University of Minnesota). The obtained EPR spectra were similar to those of other 5coordinate Co2+ complexes.164,179-181 The observed transitions are assigned to ms = ± ½
and ms = ± 3/2 Kramer doublets,164 and are consistent with low symmetry and rhombic
distortion,181 as also observed by 1H NMR. The well resolved eight lines at lower
magnetic field indicated an interaction between unpaired electrons and a
59
Co (I = 7/2)
hyperfine coupling.183 This kind of coupling was also observed in other low/high spin
low symmetry Co2+ complexes.164,170,171,179,180,183-187 The trigonal bipyramidal ligand field
and magnetic moment obtained in solution suggested a high spin Co2+ ion indicating a
high spin d7 electron configuration and 2:1:2 d orbital splitting. Meanwhile, a proposed
1:1:1:1:1 ligand field splitting in a N3S2 coordination environment was also reported.182
In all, the EPR spectra indicate quite pronounced anisotropy in the g values in the
synthetic low symmetry, high spin Co2+N3S2 complexes, which further supports a 5coordinate environment and a corresponding electron configuration.
135
Figure 35. EPR spectrum of 15.
136
Figure 36. EPR spectrum of 16.
137
Figure 37. EPR spectrum of 17.
138
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147
APPENDIX A
Crystal structure data of complex 1 TpMe,MeNiS2COMe.
148
Table 1. Crystal data and structure refinement for complex 1 TpMe,MeNiS2COMe.
Empirical formula
C17H25BN6NiOS2
Formula weight
463.07
Temperature
296(2) K
Wavelength
0.71073 Å
Crystal system
Monoclinic
Space group
P21/n
Unit cell dimensions
a = 7.8167(11) Å
α = 90°
b = 18.939(3) Å
β = 91.004(2)°
c = 14.405(2) Å
γ = 90°
Volume
2132.1(5) Å3
Z
4
Calculated density
1.443 g/cm3
Absorption coefficient
1.126 cm-1
F(000)
968
Crystal size
0.45 x 0.30 x 0.20 mm
Theta range for data collection
1.78 to 28.28°
Limiting indices
-7 ≤ h ≤ 10, -25 ≤ k ≤ 24, -11 ≤ l ≤ 19
Reflections collected / unique
15044 / 5042 [R(int) = 0.0291]
Completeness to θ = 28.28°
95.2 %
Absorption correction
Semi-empirical from equivalents
Max. and min. transmission
0.8061 and 0.6312
Refinement method
Full-matrix least-squares on F2
Data / restraints / parameters
5042 / 0 / 265
Goodness-of-fit on F2
1.068
Final R indices [I > 2σ(I)]
R1 = 0.0354, wR2 = 0.0939
R indices (all data)
R1 = 0.0380, wR2 = 0.0964
Extinction coefficient
0.0178(10)
Largest diff. peak and hole
0.624 and -0.514 e/Å3
149
Table 2. Atomic coordinates ( x104) and equivalent isotropic displacement parameters
(Å2 x 103) for complex 1 TpMe,MeNiS2COMe. U(eq) is defined as one third of the trace of
the orthogonalized Uij tensor.
x
y
z
U(eq)
Ni(1)
9444(1)
2142(1)
2126(1)
28(1)
N(1)
7303(2)
2712(1)
1908(1)
30(1)
N(3)
10644(2)
2488(1)
985(1)
29(1)
N(5)
10440(2)
2988(1)
2851(1)
26(1)
S(1)
10515(1)
1183(1)
2981(1)
42(1)
S(2)
8294(1)
1047(1)
1343(1)
51(1)
B(1)
9338(2)
3649(1)
1421(1)
26(1)
C(1)
4890(3)
1980(1)
2441(2)
49(1)
C(2)
5612(2)
2615(1)
1987(1)
33(1)
C(3)
4743(2)
3189(1)
1607(1)
36(1)
C(4)
5970(2)
3643(1)
1290(1)
31(1)
C(5)
5759(3)
4316(1)
773(2)
43(1)
C(8)
12280(3)
1480(1)
364(2)
53(1)
C(9)
11644(2)
2220(1)
330(1)
35(1)
C(10) 11990(2)
2738(1)
323(1)
39(1)
C(11) 11181(2)
3340(1)
-30(1)
33(1)
C(12) 11110(3)
4056(1)
-458(1)
46(1)
C(13) 11698(2)
2578(1)
4363(1)
38(1)
C(14) 11206(2)
3132(1)
3668(1)
30(1)
C(15) 11453(2)
3858(1)
3748(1)
36(1)
C(16) 10812(2)
4153(1)
2937(1)
32(1)
C(17) 10763(3)
4907(1)
2647(2)
47(1)
C(18) 9512(2)
672(1)
2165(1)
33(1)
C(19) 9066(3)
-481(1)
1545(2)
51(1)
N(2)
7516(2)
3352(1)
1486(1)
27(1)
N(4)
10375(2)
3182(1)
762(1)
27(1)
N(6)
10200(2)
3621(1)
2401(1)
26(1)
O(1)
9813(2)
-12(1)
2230(1)
50(1)
150
APPENDIX B
Crystal structure data of complex 3 TpMe,MeNiS2CNEt2.
151
Table 1. Crystal data and structure refinement for complex 3 TpMe,MeNiS2CNEt2.
Empirical formula
C20H32BN7NiS2
Formula weight
504.17
Temperature
293(2) K
Wavelength
0.71073 Å
Crystal system
orthorhombic
Space group
P212121
Unit cell dimensions
a = 7.9253(4) Å
α = 90°
b = 11.2651(7) Å
β = 90°
c = 28.3464(16) Å
γ = 90°
Volume
2530.7(2) Å3
Z
4
Density (calculated)
1.323 g/cm3
Absorption coefficient
9.53 cm-1
F(000)
1064
Crystal size
0.22 x 0.32 x 0.40 mm
θ range for data collection
2.31 to 27.50°
Index ranges
-8 ≤ h ≤ 10, -14 ≤ k ≤ 14, -36 ≤ l ≤ 36
Reflections collected
15529
Independent reflections
5575 [R(int) = 0.0344]
Completeness to θ = 27.50°
96.8 %
Refinement method
Full-matrix least-squares on F2
Data / restraints / parameters
5575 / 4 / 308
Goodness-of-fit on F2
1.039
Final R indices [I > 2σ(I)]
R1 = 0.0394, wR2 = 0.0972
R indices (all data)
R1 = 0.0426, wR2 = 0.0995
Absolute structure parameter
0.069(12)
Largest diff. peak and hole
0.598 and -0.371 e/Å3
152
Table 2. Atomic coordinates (x 104) and equivalent isotropic displacement parameters
(Å2 x 103) for complex 3 TpMe,MeNiS2CNEt2. U(eq) is defined as one third of the trace
of the orthogonalized Uij tensor.
x
y
z
U(eq)
Ni(1)
7885(1)
2041(1)
1330(1)
35(1)
S(1)
7480(1)
4129(1)
1354(1)
60(1)
S(2)
6780(1)
2473(1)
2103(1)
56(1)
N(1)
5846(2)
1183(2)
1066(1)
41(1)
N(2)
6169(2)
150(2)
833(1)
43(1)
N(3)
9020(2)
1890(2)
677(1)
39(1)
N(4)
8931(2)
784(2)
484(1)
41(1)
N(5)
9078(2)
490(2)
1526(1)
42(1)
N(6)
8885(2)
-439(2)
1221(1)
43(1)
N(7)
5588(4)
4691(2)
2101(1)
69(1)
C(1)
4161(3)
1321(3)
1076(1)
50(1)
C(2)
3414(3)
348(3)
856(1)
61(1)
C(3)
4686(3)
-369(3)
708(1)
55(1)
C(4)
9855(3)
2574(3)
371(1)
46(1)
C(5)
10310(3)
1893(3)
-22(1)
54(1)
C(6)
9722(3)
781(3)
60(1)
48(1)
C(7)
9911(4)
79(3)
1899(1)
56(1)
C(8)
10233(4)
-1117(3)
1839(1)
68(1)
C(9)
9569(4)
-1437(3)
1408(1)
57(1)
C(10) 3332(3)
2371(3)
1287(1)
68(1)
C(11) 4610(5)
-1528(3)
451(2)
82(1)
C(12) 10163(4)
3859(3)
448(1)
63(1)
C(13) 9874(5)
-312(4)
-235(1)
74(1)
C(14) 10414(5)
861(4)
2305(1)
77(1)
C(15) 9579(5)
-2598(3)
1159(2)
82(1)
C(16) 6520(3)
3874(2)
1885(1)
46(1)
C(17) 5422(6)
5893(3)
1919(1)
82(1)
C(18) 3924(8)
6068(5)
1615(2)
114(2)
153
C(19) 4315(7)
4341(5)
2476(2)
59(2)
C(20) 5074(8)
4422(5)
2959(2)
66(2)
C(19') 5437(13)
4604(9)
2620(3)
61(3)
C(20') 3654(14)
4122(11)
2662(6)
85(4)
B(1)
-230(2)
746(1)
41(1)
8011(4)
154
APPENDIX C
Crystal structure data of complex 5 TpPh,MeNiS2CNEt2-red.
155
Table 1. Crystal data and structure refinement for complex 5 TpPh,MeNiS2CNEt2-red.
Empirical formula
C35H38BN7NiS2
Formula weight
690.36
Temperature
293(2) K
Wavelength
0.71073 Å
Crystal system
monoclinic
Space group
P21/c
Unit cell dimensions
a = 11.9864(6) Å
α = 90°
b = 22.9361(12) Å
β = 111.214(1)°
c = 13.8614(7) Å
γ = 90°
Volume
3552.6(3) Å3
Z
4
Density (calculated)
1.291 g/cm3
Absorption coefficient
6.99 cm-1
F(000)
1448
Crystal size
0.28 x 0.38 x 0.50 mm
θ range for data collection
1.81 to 27.53°
Index ranges
-15 ≤ h ≤ 13, -25 ≤ k ≤ 29, -18 ≤ l ≤ 17
Reflections collected
23868
Independent reflections
8088 [R(int) = 0.0355]
Completeness to θ = 27.53°
98.8 %
Refinement method
Full-matrix least-squares on F2
Data / restraints / parameters
8088 / 4 / 440
Goodness-of-fit on F2
1.038
Final R indices [I>2σ(I)]
R1 = 0.0379, wR2 = 0.1036
R indices (all data)
R1 = 0.0466, wR2 = 0.1111
Largest diff. peak and hole
0.342 and -0.197 e/Å3
156
Table 2. Atomic coordinates (x 104) and equivalent isotropic displacement parameters
(Å2 x 103) for complex 5 TpPh,MeNiS2CNEt2-red. U(eq) is defined as one third of the
trace of the orthogonalized Uij tensor.
x
y
z
U(eq)
Ni(1)
1578(1)
4050(1)
8030(1)
37(1)
S(1)
1514(1)
3340(1)
6945(1)
45(1)
S(2)
2640(1)
4412(1)
7174(1)
54(1)
N(1)
1650(1)
4737(1)
8852(1)
41(1)
N(2)
1874(1)
4674(1)
9886(1)
44(1)
N(3)
746(1)
3635(1)
8782(1)
40(1)
N(4)
1250(1)
3644(1)
9845(1)
40(1)
N(5)
3434(1)
3882(1)
10245(1)
50(1)
N(6)
3445(1)
3463(1)
9555(1)
48(1)
N(7)
2972(2)
3595(1)
5902(2)
66(1)
C(1)
1396(2)
5300(1)
8622(1)
45(1)
C(2)
1456(2)
5603(1)
9513(2)
52(1)
C(3)
1745(2)
5196(1)
10289(1)
50(1)
C(4)
-176(2)
3264(1)
8536(1)
41(1)
C(5)
-264(2)
3032(1)
9437(2)
49(1)
C(6)
641(2)
3284(1)
10246(1)
43(1)
C(7)
4538(2)
3471(1)
9505(2)
54(1)
C(8)
5232(2)
3894(1)
10168(2)
80(1)
C(9)
4521(2)
4144(1)
10626(3)
80(1)
C(10) 1857(3)
5282(1)
11392(2)
73(1)
C(11) 1076(2)
5535(1)
7565(1)
49(1)
C(12) 121(2)
5314(1)
6747(2)
66(1)
C(13) -156(3)
5541(1)
5758(2)
80(1)
C(14) 518(3)
5984(1)
5590(2)
84(1)
C(15) 1454(3)
6212(1)
6395(2)
81(1)
C(16) 1734(3)
5989(1)
7381(2)
64(1)
C(17) 942(2)
3214(1)
11385(2)
56(1)
C(18) -985(2)
3158(1)
7462(1)
43(1)
157
C(19) -1456(2)
3614(1)
6786(2)
55(1)
C(20) -2290(2)
3514(1)
5809(2)
68(1)
C(21) -2654(2)
2948(1)
5486(2)
73(1)
C(22) -2174(2)
2495(1)
6144(2)
69(1)
C(23) -1353(2)
2594(1)
7127(2)
55(1)
C(24) 4781(3)
4624(2)
11417(4)
145(2)
C(25) 4866(2)
3079(1)
8819(2)
59(1)
C(26) 4237(2)
2575(1)
8427(2)
72(1)
C(27) 4555(3)
2211(2)
7774(2)
94(1)
C(28) 5507(3)
2355(2)
7490(2)
102(1)
C(29) 6141(3)
2850(2)
7870(3)
107(1)
C(30) 5834(2)
3211(2)
8527(2)
85(1)
C(31) 2463(2)
3753(1)
6560(1)
46(1)
C(32) 2774(3)
3012(1)
5418(2)
74(1)
C(33) 1892(3)
3018(1)
4331(2)
86(1)
C(34) 3554(7)
4063(4)
5492(6)
67(2)
C(35) 4887(8)
4039(5)
6086(10)
158(6)
C(34') 4016(7)
3915(4)
5821(7)
79(2)
C(35') 3613(11)
4306(5)
4931(8)
213(8)
B(1)
4068(1)
10398(2)
45(1)
2276(2)
158
APPENDIX D
Crystal structure data of complex 6 Polymorph-LT-TpPh,MeNiS2CNEt2.
159
Table 1. Crystal data and structure refinement for complex 6 Polymorph-LTTpPh,MeNiS2CNEt2.
Empirical formula
C36H40BCl2N7NiS2
Formula weight
775.29
Temperature
173(2) K
Wavelength
0.71073 Å
Crystal system
Monoclinic
Space group
P21/c
Unit cell dimensions
a = 13.5916(14) Å
α = 90°
b = 17.9002(18) Å
β = 96.854(2)°
c = 15.7783(16) Å
γ = 90°
Volume
3811.3(7) Å3
Z
4
Density (calculated)
1.351 Mg/m3
Absorption coefficient
0.795 mm-1
F(000)
1616
Crystal color, morphology
Red, Block
Crystal size
0.45 x 0.25 x 0.15 mm3
Theta range for data collection
1.51 to 27.50°
Index ranges
-17 ≤ h ≤ 17, 0 ≤ k ≤ 23, 0 ≤ l ≤ 20
Reflections collected
45510
Independent reflections
8730 [R(int) = 0.0419]
Observed reflections
6817
Completeness to θ = 27.50°
99.7%
Absorption correction
Multi-scan
Max. and min. transmission
0.8901 and 0.7162
Refinement method
Full-matrix least-squares on F2
Data / restraints / parameters
8730 / 31 / 475
Goodness-of-fit on F2
1.041
Final R indices [I > 2σ(I)]
R1 = 0.0396, wR2 = 0.0989
160
R indices (all data)
R1 = 0.0595, wR2 = 0.1133
Largest diff. peak and hole
0.687 and -0.909 e.Å-3
161
Table 2. Atomic coordinates(x 104) and equivalent isotropic displacement parameters
(Å2x 103) for complex 6 Polymorph-LT-TpPh,MeNiS2CNEt2. Ueq is defined as one third
of the trace of the orthogonalized Uij tensor.
x
y
z
Ueq
Ni1
6397(1)
5210(1)
7453(1)
20(1)
B1
7678(2)
6199(2)
6340(2)
25(1)
N1
7712(1)
6436(1)
7289(1)
23(1)
N2
7218(1)
6041(1)
7852(1)
22(1)
N3
8305(2)
5496(1)
6244(1)
25(1)
N4
7920(2)
4796(1)
6305(1)
26(1)
N5
6581(1)
6079(1)
5975(1)
23(1)
N6
5908(1)
5748(1)
6441(1)
21(1)
C1
8208(2)
7014(1)
7700(2)
28(1)
C2
8042(2)
6983(2)
8545(2)
30(1)
C3
7409(2)
6378(1)
8614(2)
26(1)
C4
8772(2)
7589(2)
7265(2)
42(1)
C5
6929(2)
6161(1)
9368(2)
29(1)
C6
7497(2)
6059(2)
10152(2)
41(1)
C7
7045(3)
5875(2)
10867(2)
52(1)
C8
6038(3)
5788(2)
10809(2)
51(1)
C9
5460(3)
5900(2)
10039(2)
45(1)
C10
5906(2)
6087(2)
9318(2)
34(1)
C11
9271(2)
5460(2)
6089(2)
34(1)
C12
9509(2)
4720(2)
6043(2)
37(1)
C13
8652(2)
4323(2)
6178(2)
29(1)
C14
9903(2)
6133(2)
6007(3)
49(1)
C15
8491(2)
3507(2)
6160(2)
31(1)
C16
9253(2)
3018(2)
6015(2)
43(1)
C17
9107(3)
2258(2)
5983(3)
52(1)
C18
8185(3)
1965(2)
6083(2)
51(1)
C19
7418(3)
2437(2)
6213(2)
50(1)
C20
7565(2)
3204(2)
6253(2)
40(1)
C21
6112(2)
6325(1)
5222(2)
25(1)
162
C22
5119(2)
6157(1)
5201(2)
26(1)
C23
5016(2)
5804(1)
5974(2)
22(1)
C24
6629(2)
6722(2)
4569(2)
36(1)
C25
4081(2)
5567(1)
6280(2)
23(1)
C26
3293(2)
5342(1)
5682(2)
29(1)
C27
2393(2)
5149(2)
5946(2)
36(1)
C28
2256(2)
5183(2)
6798(2)
37(1)
C29
3030(2)
5414(2)
7398(2)
33(1)
C30
3937(2)
5599(1)
7136(2)
26(1)
S1
6885(1)
4460(1)
8530(1)
28(1)
S2
5501(1)
4209(1)
7111(1)
23(1)
C31
6146(2)
3798(1)
7988(2)
24(1)
N7
6074(2)
3093(1)
8202(1)
30(1)
C32
6659(2)
2778(2)
8967(2)
42(1)
C33
7578(3)
2386(2)
8760(2)
53(1)
C34
5408(2)
2583(2)
7676(2)
35(1)
C35
4359(2)
2595(2)
7912(2)
45(1)
Cl1
9738(3)
3883(2)
8633(4)
130(2)
C36
9330(4)
4804(2)
8476(5)
59(2)
Cl2
10370(2)
5352(2)
8399(2)
97(1)
Cl1'
9660(4)
3909(4)
9154(5)
127(2)
C36'
9554(9)
4558(4)
8324(5)
81(2)
Cl2'
10124(10)
5367(4)
8747(9)
242(4)
163
APPENDIX E
Crystal structure data of complex 7 TpPh,MeNiS2CNPh2-red.
164
Table 1. Crystal data and structure refinement for complex 7 TpPh,MeNiS2CNPh2-red.
Empirical formula
C44H39.5BN7.5NiS2
Formula weight
806.97
Temperature
293(2) K
Wavelength
0.71073 Å
Crystal system
monoclinic
Space group
C2/c
Unit cell dimensions
a = 37.626(2) Å
α = 90°
b = 9.7449(6) Å
β = 92.636(1)°
c = 22.6279(15) Å
γ = 90°
Volume
8288.0(9) Å3
Z
8
Density (calculated)
1.293 g/cm3
Absorption coefficient
6.10 cm-1
F(000)
3368
Crystal size
0.20 x 0.34 x 0.54 mm
θ range for data collection
2.15 to 27.52°
Index ranges
-48 ≤ h ≤ 48, -12 ≤ k ≤ 10, -29 ≤ l ≤ 29
Reflections collected
27803
Independent reflections
9251 [R(int) = 0.0363]
Completeness to θ = 27.52°
97.0 %
Refinement method
Full-matrix least-squares on F2
Data / restraints / parameters
9251 / 14 / 561
Goodness-of-fit on F2
1.047
Final R indices [I > 2σ(I)]
R1 = 0.0372, wR2 = 0.0940
R indices (all data)
R1 = 0.0553, wR2 = 0.1096
Largest diff. peak and hole
0.404 and -0.197 e/Å3
165
Table 2. Atomic coordinates (x 104) and equivalent isotropic displacement parameters
(Å2 x 103) for complex 7 TpPh,MeNiS2CNPh2-red. U(eq) is defined as one third of the
trace of the orthogonalized Uij tensor.
x
y
z
U(eq)
Ni(1)
1270(1)
8039(1)
890(1)
41(1)
S(1)
1655(1)
8748(1)
252(1)
50(1)
S(2)
1492(1)
6092(1)
605(1)
54(1)
N(1)
922(1)
7203(2)
1362(1)
43(1)
N(2)
574(1)
7515(2)
1221(1)
48(1)
N(3)
1060(1)
9797(2)
1006(1)
42(1)
N(4)
702(1)
9897(2)
881(1)
46(1)
N(5)
599(1)
8058(2)
126(1)
47(1)
N(6)
672(1)
9035(2)
-285(1)
49(1)
N(7)
1861(1)
6533(2)
-369(1)
51(1)
N(8)
0
6663(6)
7500
184(3)
C(1)
925(1)
6240(2)
1788(1)
48(1)
C(2)
576(1)
5925(2)
1912(1)
60(1)
C(3)
362(1)
6741(2)
1556(1)
60(1)
C(4)
1187(1)
11072(2)
1076(1)
48(1)
C(5)
908(1)
11999(2)
986(1)
60(1)
C(6)
607(1)
11237(2)
862(1)
56(1)
C(7)
599(1)
6783(2)
-126(1)
54(1)
C(8)
677(1)
6945(2)
-704(1)
56(1)
C(9)
721(1)
8362(2)
-788(1)
48(1)
C(10) -36(1)
6825(3)
1512(2)
91(1)
C(11) 1255(1)
5708(2)
2074(1)
51(1)
C(12) 1549(1)
6533(3)
2187(1)
69(1)
C(13) 1852(1)
6019(3)
2478(1)
90(1)
C(14) 1863(1)
4667(4)
2658(1)
97(1)
C(15) 1578(1)
3839(3)
2536(2)
100(1)
C(16) 1274(1)
4352(3)
2256(1)
74(1)
C(17) 236(1)
11701(3)
713(2)
88(1)
166
C(18) 1561(1)
11350(2)
1240(1)
51(1)
C(19) 1767(1)
10450(2)
1584(1)
61(1)
C(20) 2120(1)
10722(3)
1728(1)
79(1)
C(21) 2270(1)
11904(4)
1541(2)
103(1)
C(22) 2070(1)
12807(4)
1209(2)
119(1)
C(23) 1721(1)
12543(3)
1052(2)
89(1)
C(24) 522(1)
5483(2)
195(1)
73(1)
C(25) 801(1)
9116(2)
-1328(1)
51(1)
C(26) 801(1)
10533(2)
-1343(1)
70(1)
C(27) 867(1)
11231(3)
-1862(1)
79(1)
C(28) 936(1)
10537(3)
-2365(1)
74(1)
C(29) 941(1)
9136(3)
-2356(1)
82(1)
C(30) 873(1)
8427(3)
-1843(1)
69(1)
C(31) 1698(1)
7052(2)
91(1)
45(1)
C(32) 2020(1)
7419(2)
-797(1)
50(1)
C(33) 1807(1)
8273(2)
-1144(1)
60(1)
C(34) 1963(1)
9113(3)
-1554(1)
74(1)
C(35) 2324(1)
9087(3)
-1606(1)
84(1)
C(36) 2533(1)
8229(4)
-1263(1)
91(1)
C(37) 2382(1)
7382(3)
-852(1)
73(1)
C(38) 1852(3)
5063(7)
-496(7)
63(2)
C(39) 2091(2)
4229(6)
-214(6)
111(3)
C(40) 2053(3)
2829(8)
-307(7)
160(4)
C(41) 1794(4)
2302(9)
-662(5)
138(5)
C(42) 1577(5)
3203(9)
-959(6)
194(7)
C(43) 1601(3)
4602(7)
-878(5)
131(4)
C(38') 1788(6)
5100(17)
-483(15)
56(7)
C(39') 2060(4)
4150(15)
-501(7)
68(4)
C(40') 1995(4)
2761(16)
-632(9)
82(5)
C(41') 1663(5)
2470(30)
-871(16)
112(12)
C(42') 1385(5)
3261(16)
-740(9)
93(5)
C(43') 1455(4)
4611(14)
-609(8)
75(4)
C(44) 0
7789(7)
7500
136(2)
167
C(45) 0
9277(7)
7500
182(4)
B(1)
8590(2)
734(1)
49(1)
485(1)
168
APPENDIX F
Crystal structure data of Complex 8 TpPh,MeNiS2CNPh2-green.
169
Table 1. Crystal data and structure refinement for complex 8 TpPh,MeNiS2CNPh2-green.
Empirical formula
C43H38BN7NiS2
Formula weight
786.44
Temperature
173(2) K
Wavelength
0.71073 Å
Crystal system
Monoclinic
Space group
P21
Unit cell dimensions
a = 10.8662(14) Å
α = 90°
b = 13.9155(18) Å
β = 110.920(2)°
c = 13.9283(18) Å
γ = 90°
Volume
1967.2(4) Å3
Z
2
Density (calculated)
1.328 Mg/m3
Absorption coefficient
0.640 mm-1
F(000)
820
Crystal color, morphology
Green, Block
Crystal size
0.35 x 0.18 x 0.15 mm3
Theta range for data collection
1.57 to 27.50°
Index ranges
-14 ≤ h ≤ 13, -18 ≤ k ≤ 18,0 ≤ l ≤ 18
Reflections collected
23460
Independent reflections
8920 [R(int) = 0.0362]
Observed reflections
7839
Completeness to θ = 27.50°
99.7 %
Absorption correction
Multi-scan
Max. and min. transmission
0.9101 and 0.8070
Refinement method
Full-matrix least-squares on F2
Data / restraints / parameters
8920 / 1 / 490
Goodness-of-fit on F2
1.020
Final R indices [I > 2σ(I)]]
R1 = 0.0299, wR2 = 0.0642
R indices (all data)
R1 = 0.0391, wR2 = 0.0681
170
Largest diff. peak and hole
0.250 and -0.251 e.Å-3
171
Table 2. Atomic coordinates(x 104) and equivalent isotropic displacement parameters
(Å2x 103) for complex 8 TpPh,MeNiS2CNPh2-green. Ueq is defined as one third of the
trace of the orthogonalized Uij tensor.
x
y
z
Ueq
Ni1
6168(1)
3399(1)
2813(1)
24(1)
B1
5713(2)
1336(2)
3343(2)
28(1)
N1
6279(2)
1329(1)
2469(1)
28(1)
N2
6407(2)
2174(1)
2008(1)
26(1)
C1
6718(2)
584(2)
2065(2)
32(1)
C2
7153(2)
951(2)
1322(2)
35(1)
C3
6948(2)
1942(2)
1310(2)
28(1)
C4
6716(2)
-436(2)
2405(2)
42(1)
C5
7242(2)
2667(2)
644(2)
30(1)
C6
8477(2)
2671(2)
562(2)
44(1)
C7
8801(3)
3356(3)
-26(2)
57(1)
C8
7892(3)
4030(2)
-553(2)
58(1)
C9
6654(3)
4024(2)
-497(2)
51(1)
C10
6323(2)
3339(2)
93(2)
37(1)
N3
6700(2)
1855(1)
4283(1)
25(1)
N4
7244(2)
2706(1)
4138(1)
26(1)
C11
7207(2)
1588(2)
5278(2)
29(1)
C12
8114(2)
2267(2)
5791(2)
30(1)
C13
8129(2)
2957(2)
5064(2)
27(1)
C14
6758(2)
710(2)
5663(2)
40(1)
C15
8941(2)
3825(2)
5215(2)
29(1)
C16
9377(2)
4165(2)
4446(2)
39(1)
C17
10068(2)
5024(2)
4583(2)
45(1)
C18
10371(2)
5537(2)
5483(2)
48(1)
C19
9988(2)
5182(2)
6263(2)
45(1)
C20
9281(2)
4334(2)
6130(2)
36(1)
N5
4404(2)
1878(1)
2967(1)
27(1)
N6
4351(2)
2834(1)
2702(1)
26(1)
172
C21
3179(2)
1539(2)
2810(2)
31(1)
C22
2312(2)
2281(2)
2431(2)
33(1)
C23
3064(2)
3082(2)
2375(2)
27(1)
C24
2924(2)
531(2)
3049(2)
45(1)
C25
2537(2)
4046(2)
2011(2)
30(1)
C26
1336(2)
4313(2)
2084(2)
38(1)
C27
765(3)
5194(2)
1726(2)
45(1)
C28
1399(3)
5825(2)
1296(2)
47(1)
C29
2585(3)
5575(2)
1216(2)
41(1)
C30
3150(2)
4682(2)
1554(2)
35(1)
S1
7018(1)
4583(1)
2029(1)
34(1)
S2
5985(1)
4881(1)
3662(1)
28(1)
C31
6580(2)
5370(2)
2805(2)
27(1)
N7
6694(2)
6329(1)
2706(1)
28(1)
C32
7115(2)
6735(2)
1926(2)
27(1)
C33
6362(2)
6624(2)
898(2)
38(1)
C34
6779(2)
7033(2)
160(2)
44(1)
C35
7935(2)
7542(2)
441(2)
44(1)
C36
8683(3)
7660(2)
1465(2)
45(1)
C37
8274(2)
7255(2)
2216(2)
34(1)
C38
6259(3)
6991(2)
3336(2)
35(1)
C39
7089(3)
7211(2)
4309(2)
59(1)
C40
6622(5)
7846(2)
4885(2)
86(1)
C41
5374(5)
8217(2)
4474(3)
80(1)
C42
4588(4)
7999(2)
3507(3)
70(1)
C43
5020(3)
7383(2)
2920(2)
47(1)
173
APPENDIX G
Crystal structure data of complex 9 TpPh,MeNiS2COEt.
174
Table 1. Crystal data and structure refinement for complex 9 TpPh,MeNiS2COEt.
Empirical formula
C36H37.5BN7.5NiOS2
Formula weight
724.88
Temperature
293(2) K
Wavelength
0.71073 Å
Crystal system
monoclinic
Space group
P21/n
Unit cell dimensions
a = 12.1934(6) Å
α = 90°
b = 24.2633(13) Å
β = 114.995(1)°
c = 13.8899(7) Å
γ = 90°
Volume
3724.5(3) Å3
Z
4
Density (calculated)
1.293 g/cm3
Absorption coefficient
6.72 cm-1
F(000)
1516
Crystal size
0.20 x 0.32 x 0.40 mm
θ range for data collection
2.02 to 27.51°
Index ranges
-15 ≤ h ≤ 13, -31 ≤ k ≤ 31, -17 ≤ l ≤ 16
Reflections collected
24968
Independent reflections
8388 [R(int) = 0.0378]
Completeness to θ = 27.51°
98.0 %
Refinement method
Full-matrix least-squares on F2
Data / restraints / parameters
8388 / 5 / 457
Goodness-of-fit on F2
1.022
Final R indices [I > 2σ(I)]
R1 = 0.0434, wR2 = 0.1190
R indices (all data)
R1 = 0.0533, wR2 = 0.1278
Largest diff. peak and hole
0.529 and -0.331 e/Å3
175
Table 2. Atomic coordinates (x 104) and equivalent isotropic displacement parameters
(Å2 x 103) for complex 9 TpPh,MeNiS2COEt. U(eq) is defined as one third of the trace of
the orthogonalized Uij tensor.
x
y
z
U(eq)
Ni(1)
1777(1)
1072(1)
3297(1)
36(1)
S(1)
-232(1)
755(1)
2203(1)
53(1)
S(2)
958(1)
1735(1)
1913(1)
56(1)
O(1)
-1341(1)
1474(1)
746(1)
61(1)
N(1)
1539(1)
1340(1)
4597(1)
39(1)
N(2)
2473(2)
1214(1)
5561(1)
42(1)
N(3)
2508(1)
345(1)
4028(1)
40(1)
N(4)
3364(2)
389(1)
5053(1)
41(1)
N(5)
3528(1)
1383(1)
3892(1)
40(1)
N(6)
4138(1)
1340(1)
4974(1)
41(1)
C(1)
643(2)
1536(1)
4825(2)
43(1)
C(2)
1006(2)
1534(1)
5916(2)
55(1)
C(3)
2164(2)
1326(1)
6363(2)
50(1)
C(4)
2379(2)
-196(1)
3800(2)
42(1)
C(5)
3140(2)
-494(1)
4684(2)
50(1)
C(6)
3753(2)
-117(1)
5459(2)
45(1)
C(7)
4158(2)
1741(1)
3584(2)
43(1)
C(8)
5149(2)
1937(1)
4472(2)
51(1)
C(9)
5115(2)
1675(1)
5335(2)
45(1)
C(10) 2977(3)
1213(2)
7510(2)
76(1)
C(11) -551(2)
1712(1)
4007(2)
46(1)
C(12) -681(2)
2130(1)
3295(2)
59(1)
C(13) -1823(3)
2290(1)
2565(2)
74(1)
C(14) -2836(3)
2033(2)
2542(3)
83(1)
C(15) -2723(2)
1626(2)
3247(3)
79(1)
C(16) -1589(2)
1462(1)
3986(2)
62(1)
C(17) 4711(2)
-206(1)
6559(2)
64(1)
C(18) 1566(2)
-414(1)
2749(2)
47(1)
176
C(19) 1682(3)
-260(1)
1836(2)
62(1)
C(20) 927(3)
-480(2)
861(2)
79(1)
C(21) 54(3)
-853(2)
790(3)
86(1)
C(22) -62(3)
-1014(2)
1691(3)
91(1)
C(23) 693(3)
-799(1)
2666(2)
73(1)
C(24) 5953(2)
1720(1)
6488(2)
61(1)
C(25) 3827(2)
1868(1)
2455(2)
47(1)
C(26) 3847(2)
2413(1)
2145(2)
65(1)
C(27) 3550(3)
2537(2)
1093(3)
82(1)
C(28) 3277(3)
2130(2)
357(3)
90(1)
C(29) 3272(3)
1589(2)
653(2)
81(1)
C(30) 3539(2)
1460(1)
1700(2)
60(1)
C(31) -294(2)
1344(1)
1547(2)
47(1)
C(32) -1413(3)
1976(2)
139(3)
82(1)
C(33) -2684(4)
2051(2)
-621(3)
130(2)
B(1)
3654(2)
961(1)
5593(2)
41(1)
N(7)
6340(8)
-19(5)
-528(7)
297(6)
C(34) 6383(7)
270(4)
115(7)
238(5)
C(35) 6381(5)
661(3)
899(6)
184(3)
N(8)
10015(6)
6460(13)
185(7)
C(36) 853(18)
10014(11)
5703(15)
127(9)
C(37) -309(19)
9973(14)
4770(20)
152(12)
1732(13)
177
APPENDICES H and I
Crystal structure data of allogons 10, 11 TpPh,MeNiS2CNMe2-LT.
178
Table 1. Crystal data and structure refinement for allogons 10, 11 TpPh,MeNiS2CNMe2LT.
Empirical formula
C33H34BN7NiS2
Formula weight
662.31
Temperature
123(2) K
Wavelength
0.71073 Å
Crystal system
Triclinic
Space group
P-1
Unit cell dimensions
a = 12.0040(12) Å
α = 91.034(1)°
b = 12.5359(12) Å
β = 101.353(1)°
c = 24.678(2) Å
γ = 116.788(1)°
Volume
3225.9(5) Å3
Z
4
Density (calculated)
1.364 Mg/m3
Absorption coefficient
0.766 mm-1
F(000)
1384
Crystal color, morphology
Green, Block
Crystal size
0.40 x 0.38 x 0.30 mm3
Theta range for data collection
1.70 to 27.50°
Index ranges
-15 ≤ h ≤ 15,-16 ≤ k ≤ 16, 0 ≤ l ≤ 31
Reflections collected
38246
Independent reflections
14519 [R(int) = 0.0282]
Observed reflections
11726
Completeness to θ = 27.50°
98.0%
Absorption correction
Multi-scan
Max. and min. transmission
0.8027 and 0.7492
Refinement method
Full-matrix least-squares on F2
Data / restraints / parameters
14519 / 0 / 803
Goodness-of-fit on F2
1.040
Final R indices [I > 2σ(I)]
R1 = 0.0373, wR2 = 0.0849
179
R indices (all data)
R1 = 0.0525, wR2 = 0.0934
Largest diff. peak and hole
0.548 and -1.473 e.Å-3
180
Table 2. Atomic coordinates(x 104) and equivalent isotropic displacement parameters
(Å2x 103) for allogons 10, 11 TpPh,MeNiS2CNMe2-LT. Ueq is defined as one third of the
trace of the orthogonalized Uij tensor.
x
y
z
Ueq
Ni1A
5092(1)
7425(1)
3892(1)
36(1)
B1A
2913(2)
7121(2)
4444(1)
24(1)
N1A
3898(2)
6795(2)
4803(1)
24(1)
N2A
5065(2)
7097(2)
4682(1)
23(1)
N3A
3655(2)
8422(1)
4303(1)
21(1)
N4A
4627(2)
8710(1)
4031(1)
21(1)
N5A
2213(2)
6237(2)
3905(1)
24(1)
N6A
2895(2)
5904(2)
3618(1)
30(1)
C1A
3839(2)
6302(2)
5287(1)
27(1)
C2A
4986(2)
6298(2)
5487(1)
28(1)
C3A
5740(2)
6810(2)
5103(1)
24(1)
C4A
2676(2)
5847(2)
5525(1)
36(1)
C5A
7083(2)
7064(2)
5156(1)
25(1)
C6A
7562(2)
6412(2)
5497(1)
31(1)
C7A
8833(2)
6667(2)
5575(1)
37(1)
C8A
9651(2)
7558(2)
5312(1)
36(1)
C9A
9190(2)
8214(2)
4978(1)
33(1)
C10A 7924(2)
7978(2)
4904(1)
28(1)
C11A 3518(2)
9409(2)
4419(1)
24(1)
C12A 4408(2)
10355(2)
4214(1)
25(1)
C13A 5092(2)
9893(2)
3977(1)
21(1)
C14A 2557(2)
9393(2)
4723(1)
32(1)
C15A 6175(2)
10573(2)
3718(1)
24(1)
C16A 6245(2)
11596(2)
3474(1)
32(1)
C17A 7275(3)
12283(2)
3243(1)
41(1)
C18A 8231(2)
11966(2)
3244(1)
41(1)
C19A 8178(2)
10959(2)
3485(1)
37(1)
C20A 7160(2)
10277(2)
3722(1)
30(1)
C21A 972(2)
5769(2)
3623(1)
28(1)
181
C22A 843(2)
5114(2)
3141(1)
32(1)
C23A 2056(2)
5217(2)
3155(1)
29(1)
C24A -12(2)
5965(3)
3836(1)
46(1)
C25A 2409(2)
4627(2)
2740(1)
37(1)
C26A 1820(3)
4469(3)
2176(1)
54(1)
C27A 2072(3)
3835(3)
1789(1)
65(1)
C28A 2897(3)
3363(3)
1952(1)
59(1)
C29A 3490(3)
3523(2)
2506(1)
49(1)
C30A 3251(2)
4154(2)
2897(1)
38(1)
S1A
5123(1)
7637(1)
2982(1)
36(1)
S2A
6206(1)
6463(1)
3717(1)
30(1)
C31A 5855(2)
6739(2)
3041(1)
26(1)
N7A
6121(2)
6309(2)
2619(1)
32(1)
C32A 5700(3)
6500(2)
2049(1)
44(1)
C33A 6781(3)
5570(2)
2696(1)
42(1)
Ni1B
8744(1)
7695(1)
1191(1)
23(1)
B1B
6292(2)
7763(2)
590(1)
26(1)
N1B
7275(2)
8151(2)
223(1)
26(1)
N2B
8357(2)
8012(2)
381(1)
26(1)
N3B
6872(2)
8590(2)
1149(1)
25(1)
N4B
7972(2)
8674(1)
1486(1)
24(1)
N5B
5958(2)
6455(2)
716(1)
24(1)
N6B
6917(2)
6180(2)
955(1)
25(1)
C1B
7210(2)
8513(2)
-293(1)
28(1)
C2B
8242(2)
8579(2)
-476(1)
29(1)
C3B
8942(2)
8252(2)
-47(1)
27(1)
C4B
6167(2)
8797(2)
-576(1)
36(1)
C5B
10092(2)
8114(2)
-50(1)
29(1)
C6B
10897(2)
8737(2)
-400(1)
34(1)
C7B
11968(2)
8596(2)
-416(1)
41(1)
C8B
12270(3)
7845(2)
-86(1)
44(1)
C9B
11484(3)
7222(3)
261(1)
46(1)
C10B 10407(2)
7353(2)
277(1)
39(1)
182
C11B 6439(2)
9250(2)
1399(1)
29(1)
C12B 7279(2)
9780(2)
1907(1)
32(1)
C13B 8215(2)
9397(2)
1948(1)
27(1)
C14B 5233(2)
9316(2)
1145(1)
41(1)
C15B 9270(2)
9692(2)
2450(1)
27(1)
C16B 10294(2)
10834(2)
2584(1)
44(1)
C17B 11176(3)
11150(3)
3092(1)
53(1)
C18B 11059(2)
10333(2)
3464(1)
42(1)
C19B 10037(3)
9207(2)
3342(1)
52(1)
C20B 9143(3)
8886(2)
2834(1)
47(1)
C21B 4802(2)
5476(2)
642(1)
26(1)
C22B 5002(2)
4539(2)
834(1)
29(1)
C23B 6329(2)
5006(2)
1024(1)
26(1)
C24B 3559(2)
5482(2)
403(1)
34(1)
C25B 7031(2)
4342(2)
1249(1)
29(1)
C26B 6521(3)
3460(2)
1595(1)
37(1)
C27B 7152(3)
2799(2)
1795(1)
48(1)
C28B 8279(3)
3003(2)
1653(1)
48(1)
C29B 8782(3)
3858(2)
1304(1)
42(1)
C30B 8157(2)
4524(2)
1101(1)
33(1)
S1B
9705(1)
7048(1)
1942(1)
33(1)
S2B
10927(1)
9247(1)
1448(1)
33(1)
C31B 11032(2)
8420(2)
1982(1)
27(1)
N7B
12059(2)
8810(2)
2401(1)
34(1)
C32B 12137(2)
8122(2)
2865(1)
42(1)
C33B 13191(2)
9969(2)
2429(1)
55(1)
183
APPENDIX J
Crystal structure data of complex 12 TpPh,MeNiS2CNMe2-RT.
184
Table 1. Crystal data and structure refinement for complex 12 TpPh,MeNiS2CNMe2-RT.
Empirical formula
C33H34BN7NiS2
Formula weight
662.31
Temperature
293(2) K
Wavelength
0.71073 Å
Crystal system
triclinic
Space group
P1
Unit cell dimensions
a = 12.1442(8) Å
α = 90.556(1)°
b = 12.6611(9) Å
β = 102.357(1)°
c = 25.0582(17) Å
γ = 116.994(1)°
Volume
3328.3(4) Å3
Z
4
Density (calculated)
1.322 g/cm3
Absorption coefficient
7.43 cm-1
F(000)
1384
Crystal size
0.58 x 0.40 x 0.20 mm
θ range for data collection
1.92 to 27.68°
Index ranges
-15 ≤ h ≤ 14, -16 ≤ k ≤ 15, -32 ≤ l ≤ 30
Reflections collected
23405
Independent reflections
14697 [R(int) = 0.0325]
Completeness to θ = 27.68°
94.5 %
Refinement method
Full-matrix least-squares on F2
Data / restraints / parameters
14697 / 1 / 849
Goodness-of-fit on F2
1.029
Final R indices [I > 2σ(I)]
R1 = 0.0500, wR2 = 0.1373
R indices (all data)
R1 = 0.0632, wR2 = 0.1496
Largest diff. peak and hole
1.344 and -1.030 e/Å3
185
Table 2. Atomic coordinates (x 104) and equivalent isotropic displacement parameters
(Å2 x 103) for complex 12 TpPh,MeNiS2CNMe2-RT. U(eq) is defined as one third of the
trace of the orthogonalized Uij tensor.
x
y
z
U(eq)
Ni(1)
1269(1)
7303(1)
3819(1)
44(1)
Ni(2)
5078(1)
7706(1)
1153(1)
48(1)
S(1)
-911(1)
5793(1)
3579(1)
77(1)
S(2)
292(1)
7926(1)
3068(1)
69(1)
S(3)
4921(1)
7423(1)
2069(1)
58(1)
S(4)
3789(1)
8536(1)
1294(1)
68(1)
N(1)
2008(1)
6312(1)
3529(1)
48(1)
N(2)
3114(1)
6412(1)
3865(1)
49(1)
N(3)
3092(1)
8804(1)
4040(1)
45(1)
N(4)
4046(1)
8532(1)
4283(1)
47(1)
N(5)
1691(1)
7016(1)
4628(1)
49(1)
N(6)
2757(1)
6861(1)
4778(1)
50(1)
N(7)
-2097(2)
6238(2)
2651(1)
74(1)
N(8)
7059(1)
9001(1)
1390(1)
53(1)
N(9)
7764(1)
8734(1)
1105(1)
50(1)
N(10) 5418(1)
6312(1)
984(1)
44(1)
N(11) 6358(1)
6587(1)
707(1)
46(1)
N(12) 4990(1)
7934(1)
326(1)
46(1)
N(13) 6135(1)
8205(1)
204(1)
48(1)
N(14) 3815(1)
8657(2)
2364(1)
64(1)
C(1)
1752(2)
5591(1)
3076(1)
51(1)
C(2)
2685(2)
5230(2)
3120(1)
64(1)
C(3)
3528(2)
5751(2)
3616(1)
59(1)
C(4)
4727(2)
5682(2)
3871(1)
88(1)
C(5)
684(2)
5279(2)
2580(1)
55(1)
C(6)
-217(4)
4071(3)
2422(2)
64(1)
C(7)
-1101(4)
3740(4)
1922(2)
81(2)
C(8)
-1154(4)
4621(6)
1591(3)
100(3)
186
C(9)
-261(6)
5729(5)
1754(2)
103(2)
C(10) 667(4)
6089(4)
2234(2)
76(2)
C(6')
-491(7)
4391(6)
2524(3)
111(3)
C(7')
-1423(8)
4036(7)
2021(4)
138(4)
C(8')
-1129(7)
4621(7)
1585(3)
102(3)
C(9')
-43(6)
5676(7)
1639(3)
87(2)
C(10') 882(6)
5935(7)
2146(3)
88(2)
C(11) 3675(2)
9967(1)
3973(1)
50(1)
C(12) 4996(2)
10436(2)
4169(1)
55(1)
C(13) 5192(1)
9505(2)
4359(1)
51(1)
C(14) 6433(2)
9505(2)
4612(1)
71(1)
C(15) 2981(2)
10623(2)
3743(1)
57(1)
C(16) 1878(2)
10461(2)
3880(1)
67(1)
C(17) 1267(2)
11128(2)
3671(1)
91(1)
C(18) 1744(3)
11951(2)
3333(1)
107(1)
C(19) 2849(3)
12154(2)
3197(1)
108(1)
C(20) 3483(2)
11487(2)
3399(1)
78(1)
C(21) 1132(2)
6776(1)
5051(1)
51(1)
C(22) 1826(2)
6437(2)
5470(1)
57(1)
C(23) 2834(2)
6491(1)
5285(1)
54(1)
C(24) 3863(2)
6191(2)
5557(1)
73(1)
C(25) 5(2)
6929(2)
5063(1)
56(1)
C(26) -783(2)
6302(2)
5402(1)
69(1)
C(27) -1834(2)
6455(2)
5418(1)
89(1)
C(28) -2114(2)
7221(3)
5113(1)
93(1)
C(29) -1341(2)
7852(3)
4780(1)
103(1)
C(30) -296(2)
7700(2)
4754(1)
83(1)
C(31) -1044(2)
6611(2)
3054(1)
55(1)
C(32) -3223(3)
5114(3)
2637(2)
138(2)
C(33) -2180(2)
6903(2)
2186(1)
94(1)
C(34) 7882(2)
9731(2)
1845(1)
59(1)
C(35) 9110(2)
9912(2)
1851(1)
67(1)
C(36) 9008(2)
9282(2)
1382(1)
60(1)
187
C(37) 10021(2)
9167(2)
1171(1)
90(1)
C(38) 7527(2)
10295(2)
2252(1)
74(1)
C(39) 8106(3)
10413(3)
2810(1)
117(1)
C(40) 7860(3)
11049(4)
3194(1)
154(2)
C(41) 7073(3)
11509(3)
3037(2)
148(2)
C(42) 6486(3)
11400(3)
2487(2)
116(1)
C(43) 6717(2)
10784(2)
2099(1)
87(1)
C(44) 4948(1)
5144(1)
1034(1)
47(1)
C(45) 5593(2)
4670(2)
793(1)
55(1)
C(46) 6470(1)
5601(2)
591(1)
51(1)
C(47) 7400(2)
5599(2)
285(1)
70(1)
C(48) 3878(2)
4478(1)
1288(1)
52(1)
C(49) 3805(2)
3472(2)
1535(1)
72(1)
C(50) 2773(3)
2794(2)
1758(1)
95(1)
C(51) 1841(3)
3111(2)
1746(1)
95(1)
C(52) 1897(2)
4106(2)
1508(1)
82(1)
C(53) 2910(2)
4781(2)
1278(1)
62(1)
C(54) 4312(2)
8204(1)
-97(1)
47(1)
C(55) 5034(2)
8672(2)
-483(1)
57(1)
C(56) 6173(2)
8663(2)
-282(1)
54(1)
C(57) 7316(2)
9087(2)
-520(1)
73(1)
C(58) 2978(2)
7953(1)
-149(1)
49(1)
C(59) 2163(2)
7052(2)
95(1)
58(1)
C(60) 900(2)
6805(2)
25(1)
69(1)
C(61) 442(2)
7463(2)
-304(1)
79(1)
C(62) 1235(2)
8347(2)
-558(1)
81(1)
C(63) 2494(2)
8607(2)
-481(1)
64(1)
C(64) 4135(1)
8253(2)
1963(1)
51(1)
C(65) 4204(2)
8474(2)
2935(1)
85(1)
C(66) 3110(2)
9336(2)
2261(1)
93(1)
B(1)
3711(2)
7239(2)
4413(1)
50(1)
B(2)
7092(2)
7870(2)
570(1)
50(1)
188
APPENDIX K
Crystal structure data of complex 13 (CF3COO)BpPh,MeNiS2CNPh2.
189
Table 1. Crystal data and structure refinement for complex 13
(CF3COO)BpPh,MeNiS2CNPh2.
Empirical formula
C35H29BF3N5NiO2S2
Formula weight
742.27
Temperature
293(2) K
Wavelength
0.71073 Å
Crystal system
triclinic
Space group
P1
Unit cell dimensions
a = 11.1443(8) Å
α = 87.510(1)°.
b = 12.4491(9) Å
β = 84.068(1)°.
c = 13.6203(9) Å
γ = 70.055(1)°.
Volume
1766.7(2) Å3
Z
2
Density (calculated)
1.395 g/cm3
Absorption coefficient
7.22 cm-1
F(000)
764
Crystal size
0.12 x 0.24 x 0.40 mm
θ range for data collection
2.13 to 27.55°
Index ranges
-13 ≤ h ≤ 14, -15 ≤ k ≤ 16, -17 ≤ l ≤ 17
Reflections collected
12493
Independent reflections
7832 [R(int) = 0.0364]
Completeness to θ = 27.55°
95.9 %
Refinement method
Full-matrix least-squares on F2
Data / restraints / parameters
7832 / 6 / 472
Goodness-of-fit on F2
1.026
Final R indices [I > 2σ(I)]
R1 = 0.0438, wR2 = 0.1119
R indices (all data)
R1 = 0.0568, wR2 = 0.1216
Largest diff. peak and hole
0.365 and -0.215 e/Å3
190
Table 2. Atomic coordinates (x 104) and equivalent isotropic displacement parameters
(Å2 x 103) for complex 13 (CF3COO)BpPh,MeNiS2CNPh2.U(eq) is defined as one third of
the trace of the orthogonalized Uij tensor.
x
y
z
U(eq)
Ni(1)
1469(1)
3144(1)
2486(1)
39(1)
S(1)
543(1)
2423(1)
3725(1)
53(1)
S(2)
-547(1)
3849(1)
2183(1)
47(1)
F(1)
326(6)
720(8)
1394(11)
157(7)
F(2)
1441(13)
-972(13)
1788(12)
201(8)
F(3)
1372(8)
-425(12)
320(6)
136(4)
F(1')
1571(14)
-1073(12)
851(16)
174(8)
F(2')
491(18)
623(14)
730(20)
207(14)
F(3')
834(14)
-96(18)
2085(7)
141(6)
O(1)
2400(2)
1277(1)
990(1)
54(1)
O(2)
3548(2)
-488(2)
1487(2)
100(1)
N(1)
2055(2)
3763(1)
1302(1)
42(1)
N(2)
2903(2)
3009(2)
640(1)
44(1)
N(3)
3202(2)
2297(1)
2733(1)
40(1)
N(4)
3985(2)
1675(1)
1956(1)
42(1)
N(5)
-1934(2)
2857(2)
3405(2)
55(1)
C(1)
1724(2)
4801(2)
869(2)
45(1)
C(2)
2360(2)
4704(2)
-81(2)
51(1)
C(3)
3100(2)
3574(2)
-204(2)
49(1)
C(4)
3967(3)
3004(2)
-1072(2)
70(1)
C(5)
877(2)
5841(2)
1386(2)
46(1)
C(6)
6(3)
6709(2)
866(2)
61(1)
C(7)
-760(3)
7694(2)
1335(2)
73(1)
C(8)
-672(3)
7851(2)
2312(3)
77(1)
C(9)
183(3)
7008(2)
2840(2)
73(1)
C(10) 952(3)
6011(2)
2371(2)
59(1)
C(11) 3890(2)
2044(2)
3525(1)
43(1)
C(12) 5102(2)
1255(2)
3250(2)
52(1)
191
C(13) 5132(2)
1046(2)
2267(2)
48(1)
C(14) 6205(3)
276(2)
1594(2)
69(1)
C(15) 3415(2)
2579(2)
4492(2)
47(1)
C(16) 2507(3)
3666(2)
4616(2)
58(1)
C(17) 2112(3)
4146(3)
5538(2)
71(1)
C(18) 2625(3)
3551(3)
6362(2)
82(1)
C(19) 3517(4)
2480(3)
6254(2)
89(1)
C(20) 3918(3)
1990(3)
5335(2)
71(1)
C(21) 2588(3)
217(2)
1246(2)
63(1)
C(22) 1398(4)
-100(3)
1209(3)
89(1)
C(23) -823(2)
3019(2)
3150(2)
45(1)
C(24) -3019(2)
3347(2)
2829(2)
61(1)
C(25) -2974(3)
2928(3)
1907(2)
80(1)
C(26) -4022(5)
3396(4)
1357(3)
105(1)
C(27) -5074(4)
4252(5)
1730(4)
113(2)
C(28) -5119(4)
4665(4)
2657(4)
119(2)
C(29) -4073(3)
4213(4)
3219(3)
95(1)
C(30) -2056(2)
2098(2)
4228(2)
61(1)
C(31) -2543(4)
2537(3)
5136(3)
100(1)
C(32) -2693(5)
1781(4)
5904(3)
124(2)
C(33) -2349(4)
647(4)
5726(3)
106(1)
C(34) -1845(4)
230(3)
4829(3)
95(1)
C(35) -1690(3)
954(3)
4059(2)
75(1)
B(1)
1741(2)
934(2)
45(1)
3493(3)
192
APPENDIX L
Crystal structure data of complex 14 TpPh,MeNi(pz)(OOCCF3).
193
Table 1. Crystal data and structure refinement for complex 14 TpPh,MeNi(pz)(OOCCF3).
Empirical formula
C42H38BF3N8NiO2
Formula weight
813.32
Temperature
293(2) K
Wavelength
0.71073 Å
Crystal system
triclinic
Space group
P1
Unit cell dimensions
a = 12.091(1) Å
α = 104.659(2)°
b = 12.525(1) Å
β = 94.539(2)°
c = 15.520(1) Å
γ = 118.055(2)°
Volume
1951.8(3) Å3
Z
2
Density (calculated)
1.384 g/cm3
Absorption coefficient
5.59 cm-1
F(000)
844
Crystal size
0.30 x 0.42 x 0.48 mm
θ range for data collection
1.94 to 27.57°
Index ranges
-14 ≤ h ≤ 15, -14 ≤ k ≤ 16, -19 ≤ l ≤ 20
Reflections collected
13950
Independent reflections
8720 [R(int) = 0.0268]
Completeness to θ = 27.57°
96.5 %
Refinement method
Full-matrix least-squares on F2
Data / restraints / parameters
8720 / 0 / 531
Goodness-of-fit on F2
1.057
Final R indices [I > 2σ(I)]
R1 = 0.0468, wR2 = 0.1246
R indices (all data)
R1 = 0.0566, wR2 = 0.1349
Largest diff. peak and hole
0.837 and -0.427 e/Å3
194
Table 2. Atomic coordinates (x 104) and equivalent isotropic displacement parameters
(Å2 x 103) for complex 14 TpPh,MeNi(pz)(OOCCF3). U(eq) is defined as one third of the
trace of the orthogonalized Uij tensor.
x
y
z
U(eq)
Ni(1)
7842(1)
5685(1)
7169(1)
36(1)
F(1)
4641(3)
1634(3)
6936(2)
138(2)
F(2)
5378(3)
1433(3)
8098(3)
129(2)
F(3)
4427(3)
2456(4)
8223(4)
173(2)
F(1')
4241(17)
2292(18)
7436(15)
64(6)
F(2')
5170(20)
1270(20)
7222(19)
89(8)
F(3')
4920(20)
1930(20)
8432(15)
78(7)
O(1)
6527(2)
4053(2)
7384(1)
50(1)
O(2)
7266(2)
3900(2)
8694(1)
70(1)
N(1)
6731(2)
6199(2)
6523(1)
40(1)
N(2)
7015(2)
6383(2)
5712(1)
39(1)
N(3)
9552(2)
7066(2)
7000(1)
38(1)
N(4)
9422(2)
7340(2)
6215(1)
38(1)
N(5)
7811(2)
4484(2)
5941(1)
39(1)
N(6)
8037(2)
5034(2)
5264(1)
39(1)
N(7)
8143(2)
6880(2)
8456(1)
39(1)
N(8)
8110(2)
6481(2)
9194(1)
40(1)
C(1)
5771(2)
6450(2)
6644(2)
44(1)
C(2)
5430(2)
6753(2)
5901(2)
49(1)
C(3)
6228(2)
6711(2)
5327(2)
45(1)
C(4)
6286(3)
6971(3)
4441(2)
61(1)
C(5)
5272(2)
6502(2)
7483(2)
52(1)
C(6)
4918(3)
7425(3)
7790(2)
70(1)
C(7)
4497(3)
7550(4)
8596(3)
91(1)
C(8)
4444(3)
6788(4)
9105(3)
97(1)
C(9)
4763(3)
5870(4)
8808(2)
89(1)
C(10) 5161(2)
5710(3)
7990(2)
65(1)
C(11) 10735(2)
7963(2)
7514(1)
39(1)
195
C(12) 11360(2)
8832(2)
7056(2)
46(1)
C(13) 10501(2)
8408(2)
6238(2)
43(1)
C(14) 10664(3)
8952(3)
5470(2)
61(1)
C(15) 11231(2)
7948(2)
8408(1)
44(1)
C(16) 12212(3)
9073(3)
9058(2)
62(1)
C(17) 12672(3)
9070(4)
9908(2)
80(1)
C(18) 12169(4)
7948(4)
10106(2)
83(1)
C(19) 11217(3)
6826(3)
9463(2)
71(1)
C(20) 10750(2)
6817(3)
8618(2)
54(1)
C(21) 7685(2)
3329(2)
5576(2)
43(1)
C(22) 7814(2)
3139(2)
4679(2)
50(1)
C(23) 8057(2)
4241(2)
4505(1)
44(1)
C(24) 8335(3)
4583(3)
3659(2)
62(1)
C(25) 7522(2)
2413(2)
6068(2)
50(1)
C(26) 6684(3)
1104(3)
5596(2)
74(1)
C(27) 6586(4)
196(3)
5981(3)
98(1)
C(28) 7320(4)
579(4)
6853(3)
97(1)
C(29) 8157(3)
1851(4)
7313(3)
80(1)
C(30) 8266(3)
2774(3)
6918(2)
59(1)
C(31) 8367(2)
7407(2)
9976(1)
42(1)
C(32) 8573(2)
8464(2)
9732(2)
46(1)
C(33) 8429(2)
8095(2)
8787(1)
42(1)
C(34) 8557(2)
8920(2)
8205(2)
51(1)
C(35) 8408(2)
7219(2)
10870(1)
44(1)
C(36) 8425(3)
6170(3)
10995(2)
58(1)
C(37) 8474(3)
6027(3)
11851(2)
66(1)
C(38) 8519(3)
6939(3)
12594(2)
64(1)
C(39) 8505(3)
7973(3)
12480(2)
72(1)
C(40) 8446(3)
8117(3)
11627(2)
62(1)
C(41) 6483(2)
3532(2)
7982(2)
51(1)
C(42) 5220(3)
2242(3)
7790(2)
74(1)
B(1)
6376(2)
5430(2)
39(1)
8205(2)
196
APPENDIX M
Crystal structure data of complex 15 TpPh,MeCoS2CNEt2.
197
Table 1. Crystal data and structure refinement for complex 15 TpPh,MeCoS2CNEt2.
Empirical formula
C35H38BCoN7S2
Formula weight
690.58
Temperature
293(2) K
Wavelength
0.71073 Å
Crystal system
triclinic
Space group
P1
Unit cell dimensions
a = 11.6837(8) Å
α = 99.850(1)°
b = 12.1413(9) Å
β = 90.523(1)°
c = 25.4394(19) Å
γ = 90.403(1)°
Volume
3555.2(4) Å3
Z
4
Density (calculated)
1.290 g/cm3
Absorption coefficient
6.35 cm-1
F(000)
1444
Crystal size
0.20 x 0.36 x 0.48 cm
θ range for data collection
1.92 to 27.66°
Index ranges
-15 ≤ h ≤ 13, -15 ≤ k ≤ 15, -33 ≤ l ≤ 33
Reflections collected
25023
Independent reflections
15692 [R(int) = 0.0384]
Completeness to θ = 27.66°
94.6 %
Max. and min. transmission
0.884 and 0.750
Refinement method
Full-matrix least-squares on F2
Data / restraints / parameters
15692 / 23 / 849
Goodness-of-fit on F2
1.018
Final R indices [I > 2σ(I)]
R1 = 0.0525, wR2 = 0.1512
R indices (all data)
R1 = 0.0757, wR2 = 0.1716
Largest diff. peak and hole
0.391 and -0.323 e/Å3
198
Table 2. Atomic coordinates (x 104) and equivalent isotropic displacement parameters
(Å2 x 103) for complex 15 TpPh,MeCoS2CNEt2. U(eq) is defined as one third of the trace
of the orthogonalized Uij tensor.
x
y
z
U(eq)
Co(1) 3056(1)
3134(1)
1099(1)
44(1)
Co(2) 8172(1)
6736(1)
3985(1)
46(1)
S(1)
1053(1)
2975(1)
1187(1)
63(1)
S(2)
2658(1)
3987(1)
2012(1)
49(1)
S(3)
6162(1)
6523(1)
4002(1)
70(1)
S(4)
7631(1)
5881(1)
3083(1)
55(1)
N(1)
4373(2)
2083(2)
1276(1)
45(1)
N(2)
5362(2)
2150(2)
995(1)
46(1)
N(3)
3234(2)
2414(2)
252(1)
46(1)
N(4)
4359(2)
2167(2)
126(1)
45(1)
N(5)
4172(2)
4356(2)
917(1)
46(1)
N(6)
5147(2)
3960(2)
652(1)
48(1)
N(7)
403(2)
3964(2)
2161(1)
57(1)
N(8)
9246(2)
7920(2)
3729(1)
49(1)
N(9)
10344(2)
7910(2)
3923(1)
49(1)
N(10) 8525(2)
7668(2)
4783(1)
48(1)
N(11) 9658(2)
7968(2)
4860(1)
46(1)
N(12) 9501(2)
5650(2)
4114(1)
47(1)
N(13) 10453(2)
6187(2)
4360(1)
49(1)
C(1)
4649(2)
1586(2)
1695(1)
51(1)
C(2)
5823(3)
1341(3)
1678(1)
59(1)
C(3)
6242(2)
1712(2)
1237(1)
51(1)
C(4)
7440(2)
1671(3)
1019(2)
68(1)
C(5)
3808(3)
1380(2)
2093(1)
58(1)
C(6)
2672(3)
1126(3)
1955(2)
70(1)
C(7)
1882(4)
985(3)
2340(2)
89(1)
C(8)
2231(5)
1077(4)
2868(2)
97(2)
C(9)
3344(5)
1287(4)
3003(2)
99(1)
199
C(10) 4130(4)
1444(3)
2621(2)
76(1)
C(11) 2608(2)
1854(2)
-152(1)
46(1)
C(12) 3317(2)
1229(2)
-529(1)
52(1)
C(13) 4416(2)
1437(2)
-341(1)
47(1)
C(14) 5522(3)
975(3)
-575(1)
65(1)
C(15) 1349(2)
1960(3)
-188(1)
54(1)
C(16) 674(3)
1033(3)
-380(2)
76(1)
C(17) -513(3)
1150(4)
-435(2)
95(1)
C(18) -1005(3)
2163(5)
-306(2)
88(1)
C(19) -350(3)
3095(4)
-114(2)
79(1)
C(20) 823(2)
2990(3)
-60(1)
61(1)
C(21) 4279(2)
5472(2)
1022(1)
54(1)
C(22) 5317(3)
5796(3)
830(2)
65(1)
C(23) 5846(2)
4834(3)
599(1)
56(1)
C(24) 6972(3)
4699(3)
329(2)
73(1)
C(25) 3387(3)
6216(3)
1289(1)
60(1)
C(26) 2227(3)
5986(3)
1203(1)
66(1)
C(27) 1416(4)
6738(4)
1447(2)
86(1)
C(28) 1759(5)
7730(4)
1762(2)
99(2)
C(29) 2887(5)
7946(4)
1849(2)
106(2)
C(30) 3705(4)
7218(3)
1611(2)
83(1)
C(31) 1265(2)
3680(2)
1831(1)
48(1)
C(32) 610(3)
4541(3)
2714(1)
64(1)
C(33) 769(3)
5765(3)
2766(2)
79(1)
C(34) -793(3)
3740(4)
1987(2)
83(1)
C(35) -1272(4)
4625(5)
1704(2)
117(2)
C(36) 9284(3)
8409(2)
3297(1)
55(1)
C(37) 10410(3)
8694(3)
3201(1)
62(1)
C(38) 11059(3)
8358(2)
3597(1)
57(1)
C(39) 12331(3)
8405(3)
3677(2)
78(1)
C(40) 8229(3)
8599(3)
3000(2)
68(1)
C(41) 7197(3)
8837(3)
3265(2)
83(1)
C(42) 6209(4)
8979(4)
2977(3)
113(2)
200
C(43) 6239(7)
8913(5)
2451(3)
133(3)
C(44) 7237(8)
8698(5)
2173(3)
137(2)
C(45) 8242(5)
8548(4)
2453(2)
104(2)
C(46) 7969(2)
8240(2)
5201(1)
46(1)
C(47) 8745(2)
8905(2)
5539(1)
50(1)
C(48) 9804(2)
8708(2)
5315(1)
45(1)
C(49) 10939(2)
9202(3)
5510(1)
59(1)
C(50) 6719(2)
8160(3)
5283(1)
54(1)
C(51) 6166(3)
7161(4)
5280(2)
79(1)
C(52) 4997(3)
7131(5)
5392(2)
100(2)
C(53) 4394(3)
8076(6)
5497(2)
105(2)
C(54) 4922(4)
9089(5)
5511(2)
106(2)
C(55) 6091(3)
9146(4)
5403(2)
81(1)
C(56) 9701(2)
4546(2)
4067(1)
49(1)
C(57) 10761(3)
4386(3)
4298(1)
60(1)
C(58) 11215(2)
5431(3)
4476(1)
56(1)
C(59) 12319(3)
5765(3)
4763(2)
79(1)
C(60) 8937(2)
3658(2)
3788(1)
52(1)
C(61) 7755(3)
3759(3)
3774(1)
62(1)
C(62) 7084(3)
2913(3)
3487(2)
75(1)
C(63) 7579(4)
1958(3)
3218(2)
83(1)
C(64) 8748(4)
1836(3)
3234(2)
85(1)
C(65) 9421(3)
2679(3)
3515(2)
67(1)
C(66) 6278(2)
5974(3)
3328(1)
59(1)
C(67) 4189(3)
5698(5)
3257(2)
103(2)
C(68) 3851(4)
4645(6)
3461(2)
118(2)
B(1)
5337(2)
2695(3)
492(1)
46(1)
B(2)
10559(2)
7468(3)
4450(1)
49(1)
N(14) 5362(2)
5659(3)
3026(1)
87(1)
C(69) 5448(4)
5422(4)
2424(2)
67(2)
C(70) 5699(4)
4195(4)
2262(2)
74(2)
C(69') 5554(10)
4660(8)
2586(4)
52(4)
C(70') 5592(15)
5259(15)
2097(5)
83(5)
201
APPENDIX N
Crystal structure data of complex 16 TpPh,MeCoS2CNPh2.
202
Table 1. Crystal data and structure refinement for complex 16 TpPh,MeCoS2CNPh2.
Empirical formula
C43H38BCoN7S2
Formula weight
786.66
Temperature
293(2) K
Wavelength
0.71073 Å
Crystal system
monoclinic
Space group
P21
Unit cell dimensions
a = 10.9428(7) Å
α = 90°
b = 14.0612(8) Å
β = 110.040(1)°
c = 13.9826(8) Å
γ = 90°
Volume
2021.2(2) Å3
Z
2
Density (calculated)
1.293 g/cm3
Absorption coefficient
5.68 cm-1
F(000)
818
Crystal size
0.36 x 0.44 x 0.54 mm
θ range for data collection
2.06 to 27.55°
Index ranges
-14 ≤ h ≤ 13, -17 ≤ k ≤ 18, -17 ≤ l ≤ 18
Reflections collected
12927
Independent reflections
7370 [R(int) = 0.0268]
Completeness to θ = 27.55°
97.7 %
Refinement method
Full-matrix least-squares on F2
Data / restraints / parameters
7370 / 1 / 490
Goodness-of-fit on F2
1.014
Final R indices [I > 2σ(I)]
R1 = 0.0339, wR2 = 0.0855
R indices (all data)
R1 = 0.0365, wR2 = 0.0871
Absolute structure parameter
0.087(9)
Largest diff. peak and hole
0.184 and -0.199 e/Å3
203
Table 2. Atomic coordinates (x 104) and equivalent isotropic displacement parameters
(Å2 x 103) for complex 16 TpPh,MeCoS2CNPh2. U(eq) is defined as one third of the trace
of the orthogonalized Uij tensor.
x
y
z
U(eq)
Co(1) 3789(1)
1543(1)
2146(1)
46(1)
S(1)
3032(1)
352(1)
2988(1)
61(1)
S(2)
3995(1)
44(1)
1308(1)
52(1)
N(1)
2722(2)
2277(1)
845(1)
48(1)
N(2)
3275(2)
3127(1)
734(2)
48(1)
N(3)
3531(2)
2784(1)
2987(2)
50(1)
N(4)
3693(2)
3623(1)
2546(2)
52(1)
N(5)
5619(2)
2140(1)
2309(1)
47(1)
N(6)
5553(2)
3082(1)
2030(2)
51(1)
N(7)
3334(2)
-1377(1)
2307(2)
53(1)
C(1)
1875(2)
2053(1)
-74(2)
50(1)
C(2)
1897(2)
2752(2)
-773(2)
56(1)
C(3)
2793(2)
3412(2)
-243(2)
54(1)
C(4)
2989(2)
3014(2)
3683(2)
52(1)
C(5)
2804(3)
3998(2)
3677(2)
65(1)
C(6)
3263(3)
4362(2)
2957(2)
60(1)
C(7)
6895(2)
1899(2)
2607(2)
50(1)
C(8)
7626(3)
2689(2)
2517(2)
61(1)
C(9)
6751(3)
3419(2)
2152(2)
59(1)
C(10) 1068(2)
1186(2)
-234(2)
54(1)
C(11) 661(3)
813(2)
525(3)
72(1)
C(12) -35(3)
-34(3)
372(3)
87(1)
C(13) -345(4)
-500(3)
-530(4)
95(1)
C(14) 11(3)
-129(3)
-1301(3)
87(1)
C(15) 719(3)
713(2)
-1164(2)
69(1)
C(16) 3231(3)
4295(2)
-614(3)
77(1)
C(17) 2673(3)
2297(2)
4338(2)
56(1)
C(18) 3575(3)
1639(2)
4893(2)
67(1)
204
C(19) 3241(4)
971(3)
5495(3)
93(1)
C(20) 2004(5)
976(4)
5538(3)
103(1)
C(21) 1115(4)
1619(4)
5010(3)
107(1)
C(22) 1442(3)
2289(3)
4401(3)
84(1)
C(23) 3310(4)
5378(2)
2641(3)
77(1)
C(24) 7421(3)
945(2)
2971(2)
55(1)
C(25) 6804(3)
318(2)
3419(2)
64(1)
C(26) 7366(4)
-571(2)
3758(2)
81(1)
C(27) 8525(4)
-823(3)
3670(3)
88(1)
C(28) 9156(4)
-200(3)
3234(3)
87(1)
C(29) 8601(3)
672(2)
2880(2)
69(1)
C(30) 6992(4)
4414(2)
1874(3)
87(1)
C(31) 3442(3)
-426(1)
2196(2)
48(1)
C(32) 2923(2)
-1774(1)
3094(2)
51(1)
C(33) 3677(3)
-1688(2)
4102(2)
70(1)
C(34) 3269(3)
-2085(3)
4840(2)
81(1)
C(35) 2115(4)
-2569(3)
4576(3)
82(1)
C(36) 1351(4)
-2652(3)
3568(3)
83(1)
C(37) 1759(3)
-2264(2)
2821(2)
65(1)
C(38) 3741(3)
-2036(1)
1669(2)
63(1)
C(39) 4980(4)
-2421(2)
2060(4)
88(1)
C(40) 5380(6)
-3032(2)
1433(6)
127(2)
C(41) 4582(9)
-3259(2)
507(6)
140(3)
C(42) 3356(10)
-2890(3)
141(4)
157(3)
C(43) 2906(6)
-2259(2)
728(3)
106(2)
B(1)
3619(2)
1677(2)
52(1)
4251(3)
205
APPENDIX O
Crystal structure data of complex 17 TpPh,MeCoS2COEt.
206
Table 1. Crystal data and structure refinement for complex 17 TpPh,MeCoS2COEt.
Empirical formula
C33H33BCoN6OS2
Formula weight
663.51
Temperature
293(2) K
Wavelength
0.71073 Å
Crystal system
orthorhombic
Space group
Pbca
Unit cell dimensions
a = 12.8047(8) Å
α = 90°
b = 21.0708(14) Å
β = 90°
c = 24.3698(16) Å
γ = 90°
Volume
6575.1(7) Å3
Z
8
Density (calculated)
1.341 g/cm3
Absorption coefficient
6.85 cm-1
F(000)
2760
Crystal size
0.18 x 0.40 x 0.54 mm
θ range for data collection
2.04 to 27.52°
Index ranges
-15 ≤ h ≤ 16, -27 ≤ k ≤ 26, -31 ≤ l ≤ 31
Reflections collected
42866
Independent reflections
7509 [R(int) = 0.0472]
Completeness to θ = 27.52°
99.4 %
Refinement method
Full-matrix least-squares on F2
Data / restraints / parameters
7509 / 0 / 401
Goodness-of-fit on F2
1.053
Final R indices [I > 2σ(I)]
R1 = 0.0354, wR2 = 0.0935
R indices (all data)
R1 = 0.0517, wR2 = 0.1073
Largest diff. peak and hole
0.263 and -0.319 e/Å3
207
Table 2. Atomic coordinates (x 104) and equivalent isotropic displacement parameters
(Å2 x 103) for complex 17 TpPh,MeCoS2COEt. U(eq) is defined as one third of the trace
of the orthogonalized Uij tensor.
x
y
z
U(eq)
Co(1) 8760(1)
1575(1)
3564(1)
36(1)
S(1)
10444(1)
1181(1)
3713(1)
55(1)
S(2)
8719(1)
405(1)
3311(1)
55(1)
O(1)
10703(1)
36(1)
3387(1)
70(1)
N(1)
7327(1)
1622(1)
3953(1)
37(1)
N(2)
6715(1)
2113(1)
3772(1)
37(1)
N(3)
8956(1)
2539(1)
3854(1)
36(1)
N(4)
8144(1)
2925(1)
3698(1)
37(1)
N(5)
8238(1)
1914(1)
2819(1)
39(1)
N(6)
7484(1)
2377(1)
2850(1)
39(1)
C(1)
6727(1)
1267(1)
4286(1)
39(1)
C(2)
5726(1)
1525(1)
4304(1)
45(1)
C(3)
5738(1)
2052(1)
3980(1)
41(1)
C(4)
4882(1)
2509(1)
3855(1)
57(1)
C(5)
7126(1)
732(1)
4607(1)
43(1)
C(6)
8161(2)
695(1)
4772(1)
58(1)
C(7)
8491(2)
211(1)
5118(1)
74(1)
C(8)
7795(2)
-236(1)
5302(1)
77(1)
C(9)
6784(2)
-212(1)
5136(1)
74(1)
C(10) 6443(2)
267(1)
4795(1)
58(1)
C(11) 9653(1)
2921(1)
4099(1)
38(1)
C(12) 9298(2)
3545(1)
4093(1)
47(1)
C(13) 8337(2)
3531(1)
3839(1)
43(1)
C(14) 7583(2)
4059(1)
3736(1)
59(1)
C(15) 10621(1)
2691(1)
4360(1)
43(1)
C(16) 10623(2)
2154(1)
4687(1)
55(1)
C(17) 11542(2)
1966(2)
4948(1)
76(1)
C(18) 12440(2)
2314(2)
4881(1)
82(1)
208
C(19) 12436(2)
2850(2)
4569(1)
73(1)
C(20) 11535(2)
3041(1)
4308(1)
55(1)
C(21) 8271(1)
1728(1)
2294(1)
42(1)
C(22) 7542(2)
2067(1)
1988(1)
50(1)
C(23) 7056(1)
2470(1)
2350(1)
44(1)
C(24) 6194(2)
2935(1)
2247(1)
63(1)
C(25) 8996(2)
1232(1)
2100(1)
48(1)
C(26) 10047(2)
1241(1)
2244(1)
56(1)
C(27) 10707(2)
764(2)
2065(1)
78(1)
C(28) 10322(3)
286(2)
1742(1)
98(1)
C(29) 9292(3)
283(2)
1592(1)
98(1)
C(30) 8625(2)
750(1)
1766(1)
71(1)
C(31) 9987(2)
485(1)
3457(1)
50(1)
C(32) 10404(2)
-567(1)
3150(2)
94(1)
C(33) 11382(3)
-935(2)
3068(3)
151(2)
B(1)
2646(1)
3412(1)
39(1)
7171(2)
209
APPENDIX P
Crystal structure data of complex 18 TpPh,MeNi(THF)(CH3CN).
210
Table 1. Crystal data and structure refinement for complex 18 TpPh,MeNi(THF)(CH3CN).
Empirical formula
C40H47B2F4N7NiO2
Formula weight
814.18
Temperature
123(2) K
Wavelength
0.71073 Å
Crystal system
Monoclinic
Space group
P21/n
Unit cell dimensions
a = 11.659(2) Å
α = 90°
b = 31.333(6) Å
β = 117.911(3)°
c = 12.475(3) Å
γ = 90°
Volume
4027.0(14) Å3
Z
4
Density (calculated)
1.343 Mg/m3
Absorption coefficient
0.544 mm-1
F(000)
1704
Crystal color, morphology
Green, Block
Crystal size
0.25 x 0.25 x 0.20 mm3
Theta range for data collection
1.96 to 25.14°
Index ranges
-13 ≤ h ≤ 12,0 ≤ k ≤ 37,0 ≤ l ≤ 14
Reflections collected
19749
Independent reflections
7089 [R(int) = 0.0807]
Observed reflections
4522
Completeness to θ = 25.14°
98.6 %
Absorption correction
Multi-scan
Max. and min. transmission
0.9733 and 0.7725
Refinement method
Full-matrix least-squares on F2
Data / restraints / parameters
7089 / 0 / 509
Goodness-of-fit on F2
1.070
Final R indices [I > 2σ(I)]
R1 = 0.0747, wR2 = 0.1806
R indices (all data)
R1 = 0.1292, wR2 = 0.2148
211
Largest diff. peak and hole
1.237 and -1.210 e.Å-3
212
Table 2. Atomic coordinates(x 104) and equivalent isotropic displacement parameters
(Å2x 103) for complex 18 TpPh,MeNi(THF)(CH3CN). Ueq is defined as one third of the
trace of the orthogonalized Uij tensor.
x
y
z
Ueq
Ni1
5374(1)
1326(1)
4319(1)
19(1)
B1
4161(6)
904(2)
1848(6)
25(1)
N1
3090(4)
1089(1)
2131(4)
25(1)
N2
3431(4)
1220(1)
3294(4)
23(1)
C1
1803(5)
1147(2)
1419(5)
26(1)
C2
1293(5)
1311(2)
2134(5)
28(1)
C3
2336(5)
1345(2)
3309(5)
24(1)
C4
1134(6)
1033(2)
105(5)
34(1)
C5
2359(5)
1459(2)
4460(5)
24(1)
C6
1691(6)
1805(2)
4574(6)
37(2)
C7
1804(7)
1913(2)
5703(6)
45(2)
C8
2558(6)
1671(2)
6712(6)
41(2)
C9
3228(6)
1320(2)
6604(5)
36(1)
C10
3126(5)
1214(2)
5483(5)
29(1)
N3
5063(4)
1273(1)
1894(4)
23(1)
N4
5501(4)
1556(1)
2853(4)
22(1)
C11
5583(5)
1375(2)
1161(4)
23(1)
C12
6373(5)
1724(2)
1650(5)
24(1)
C13
6285(5)
1835(2)
2697(4)
21(1)
C14
5252(6)
1134(2)
18(5)
35(1)
C15
6865(5)
2202(2)
3490(5)
22(1)
C16
8145(5)
2311(2)
3872(5)
30(1)
C17
8705(6)
2654(2)
4642(5)
36(1)
C18
7978(6)
2891(2)
5047(5)
34(1)
C19
6686(6)
2793(2)
4646(5)
33(1)
C20
6118(5)
2453(2)
3867(5)
24(1)
N5
4973(4)
575(1)
2830(4)
23(1)
N6
5558(4)
697(1)
4036(4)
22(1)
C21
5264(5)
163(2)
2736(5)
26(1)
213
C22
6011(5)
12(2)
3887(5)
29(1)
C23
6167(5)
349(2)
4682(5)
24(1)
C24
4843(6)
-51(2)
1542(5)
34(1)
C25
6874(5)
342(2)
6026(5)
24(1)
C26
7678(5)
3(2)
6614(5)
33(1)
C27
8342(6)
-18(2)
7869(6)
41(2)
C28
8202(6)
309(2)
8554(5)
37(2)
C29
7396(6)
650(2)
7990(5)
34(1)
C30
6711(5)
663(2)
6723(5)
27(1)
N7
5166(4)
1823(1)
5231(4)
25(1)
C31
5107(5)
2086(2)
5833(5)
27(1)
C32
5048(6)
2425(2)
6607(6)
41(2)
O1
7373(3)
1391(1)
5370(3)
25(1)
C33
8326(5)
1181(2)
5104(5)
31(1)
C34
9511(6)
1164(2)
6305(7)
53(2)
C35
9478(6)
1571(2)
6896(6)
49(2)
C36
8066(5)
1664(2)
6430(5)
32(1)
B2
7592(7)
1865(3)
9242(6)
37(2)
F1
8443(5)
2066(2)
8928(4)
93(2)
F2
8262(4)
1590(2)
10214(4)
71(1)
F3
6994(4)
2173(1)
9613(3)
54(1)
F4
6677(3)
1640(1)
8286(3)
41(1)
O2
7853(7)
264(2)
1410(6)
94(2)
C37
8389(9)
-110(3)
2072(11)
96(3)
C38
9120(11)
32(4)
3322(10)
98(3)
C39
9370(10)
530(4)
3218(9)
107(4)
C40
8223(9)
635(3)
2191(9)
87(3)