ACTA UNIVERSITATIS PALACKIANAE OLOMUCENSIS
FACULTAS RERUM NATURALIUM 2002
CHEMICA 41
COBALT AND NICKEL COMPLEXES
WITH MALEONITRILEDITHIOLATE
AND SELECTED N,P-LIGANDS
Jiří Kameníček*, Pavlína Solichová, Kateřina Mrkvová
Department of Inorganic and Physical Chemistry, Palacký University, Křížkovského 10,
771 47 Olomouc, Czech Republic
e-mail: [email protected]
Received May 31, 2002
Accepted July 25, 2002
Abstract
The new complex compounds of composition [Ni(en)2(mnt)] (I), [Ni(1,2-dap)2
(mnt)].H2O (II), [Ni(n-phen)(mnt)] (III), [Ni2(4,4’-bpy)4(mnt)2Cl(H2O)2].2H2O (IV),
[Ni(dpp)(mnt)].H2O (V); [Co(phen)(mnt)].H2O (VI), [Co(dppe)(mnt)].2H2O (VII)
and (Me3PhN)2[Ni(mnt)2] (VIII) (en = ethylenediamine, 1,2-dap = 1,2-diamino2–
propane, n-phen = 5-nitro-1,10-phenanthroline, bpy = bipyridine, mnt = maleonitriledithiolate, dppe = 1,2-bis(diphenylphosphino)ethane, dppp = 1,3-bis(diphenyl+
phosphino)propane, Me3PhN = trimethylphenylammonium) have been synthesized
and studied by common physico-chemical measurements. For compound VIII, the
X-ray structure was solved, which confirms the nearly square coordination around the
central atom in the NiS4 chromophore.
Key words: Cobalt(II), Nickel(II) maleonitriledithiolates, synthesis, X-ray structure, physico-chemical study.
Introduction
Recently, some literature information on cobalt and nickel complexes with
1,2-dithiolates has been made available. An overall review of all these compounds is
* Author for correspondence
17
1
given in literature . These compounds exhibit interesting properties and technical
2
applications (superconductors, pesticides, Q-switching dyes for IR spectroscopy)
3
and, moreover, they are able to stabilize higher oxidation states of the central atom .
Most papers deal with compounds containing aromatic 1,2-dithiolates and N,P-ligands
4, 5
in the coordination sphere . As to aliphatic dithiolate complexes, compounds con6
taining maleonitriledithiolates as ligands were studied preferably , but little attention
was paid to the derivatives with mixed ligands, containing for instance bidentate
N,N and P,P-donors in the coordination sphere.
The aim of this work was the synthesis and physico-chemical study of new nickel
and cobalt coordination compounds with maleonitriledithiolate and selected, mostly
bidentate nitrogen and phosphorus donor ligands.
Materials and methods
CoCl2.6H2O, NiCl2.6H2O, methanol and ether were from LACHEMA Brno, remaining reagents were products from FLUKA, all of “p. a.” purity.
The content of cobalt and nickel was determined by chelatometric titration on
7
murexid as indicator . Phosphorus was estimated by gravimetric analysis as
8
(NH4)3PO4.12MoO3.6H2O. C, H, N, S analyses were performed on an EA 1108
instrument (FISONS). Magnetic susceptibilities were measured by the Faraday method
using Co[Hg(NCS)4] as a calibrant on a laboratory- designed instrument with a LeyboldHeraeus cryostat and a Sartorius 4434 MP-8 microbalance. Diamagnetic corrections
were made using Pascal constants9. Conductivities were measured with a Conductivity
Meter OK 102/1 (Radelkis Budapest) at 25 °C. Diffuse-reflectance electronic absorption
spectra (45 000–11 000 cm–1) were carried out on a Specord M 40 and IR spectra
(4000–400 cm–1) were recorded on a Specord M 80 (Carl Zeiss, Jena) using nujol
mulls. Thermal analysis was performed on a Derivatograph Q 1500 D with gradient
5 °C/min. X-ray structure analysis was measured using a diffractometer KUMA KM-4
with k-axis and computed by standard SHELX-program package10, 11.
Syntheses of complexes
Compound I was prepared by mixing water solution (10 cm3) of NiCl2.6H2O
(1 mmol) with ethylenediamine (1 mmol) followed by the reaction with water solution
(15 cm3) of Na2(mnt) (1 mmol). After 2 h stirring the yellow precipitate formed was
filtered, washed with water and ether, dried under an infra-lamp at 30 °C and stored in
a dessicator with KOH. Yield 60 %.
Complex II was synthesized similarly using Ni(1,2-dap)2Cl2 as starting material.
Yield 50 %.
Complex III formed by combination of ethanol-water (3 : 1; 15 cm3) solutions of
Na2(mnt) (2.5 mmol) and Ni(NO3)2.6H2O (1.25 mmol) with n-phen (2.5 mmol) and
Ni(NO3)2.6H2O (1.25 mmol). The mixture was stirred for 3 h and the resulting substance was filtered, washed with water, dried at room temperature and and stored in
a dessicator with KOH. Yield 55 %.
18
Compound IV was prepared similarly by the reaction of Na2(mnt) (1 mmol),
4,4’-bpy (2 mmol) and NiCl2.6H2O (1 mmol); in the case of V, the ethanolic solutions
were used. Yields 50 %, 40 %, respectively.
Complexes VI, VII were obtained analogously by reaction of the same molar ratio
of components: phen, CoCl2.6H2O and Na2(mnt); dppe, CoCl2.6H2O, respectively (in
the case of dppe, the solution in ethanol-chlorophorm 1 : 1 was used for better
solubility). Yields 55 %.
3
Compound VIII was synthesized by mixing water solutions (10 cm ): Na2(mnt)
(2.5 mmol), (Me3PhN)Cl (2.5 mmol) and slow addition of NiCl2.6H2O (1.25 mmol, in
3
5 cm water). The resulting orange crystals suitable for X-ray analysis were recrystallized from ethanol-acetonitrile mixture (1 : 1).
Results and discussion
Analytical data for synthesized complexes are given in Table 1; the selected physico-chemical results are listed in Table 2.
A) Nickel complexes (I–V)
As for I, II we can conclude that both compounds exhibit probably a distorted
octahedral coordination with NiS2N4 chromophore, although the meff-values are very
low (see Table 2). This conclusion is supported also by the results of electronic
spectroscopy – maxima at 18 000 and 19 000 cm–1 can be assigned to the 3A2g ® 3T1g(F)
and maxima at 21 000, 26 000 and 27 000 cm-1 to the 3A2g ® 3T1g(P) transitions for
Ni(II) in the octahedral coordination. Bands over 30 000 cm–1 belong probably to
CT-transitions12. The values of molar conductivity show that both complexes are nonelectrolytes13, which is in accord with the conclusions above. For compound I, the
thermal analysis was performed (begin of decomposition at 166 °C, end at 700 °C; exoeffect at 300 °C due to oxidation; final product of decomposition is NiO – Dmcalc./found =
= 76.6/75.8 %, no thermal stable intermediate was recorded).
Complex III with n-phen exhibits meff = 2.13 BM, which is very difficult to explain –
for a coordination number four it cannot be assumed as a tetrahedron (meff =
= 3.5–4.2 BM) and a square polyhedron is diamagnetic. Maybe this compound
contains analytically non-detectable paramagnetic species or possess a square-tetrahedron equilibrium, which was recently described14. Unlike octahedral I, II this
sample exhibits no transitions between 21 000–27 000 cm–1; the maximum at 17 000 cm–1
can be assigned to the 1A1g ® 1A2g transition, typical of Ni(II) in the square coordination. The complex is non-electrolyte in dimethylformamide solution.
Very interesting results were obtained for complex IV. The meff value (3.15 BM;
2.23 BM per one nickel atom) cannot be simply interpreted. Therefore, the low
temperature dependence of magnetic susceptibility was measured (see Fig. 1).
A significant decreasing of effective magnetic moment indicates probably an antiferromagnetic interaction between nickel atoms in a binuclear complex. This result
19
can be interpreted most likely by the formation of the dimer species with spin values
1
2
/2, /2 or we can assume the formation of a polymeric octahedral coordination.
Complex V containing bidentate P, P-ligand is diamagnetic; this fact together with
spectroscopy results indicates categorically to the square coordination with NiS2P2
chromophore.
Results of IR-spectroscopy confirm the presence of some characteristic vibra15
tions for all synthesized compounds (see Table 2).
Fig. 1. Temperature dependence meff for [Ni2(4,4’-bpy)4(mnt)2Cl(H2O)2].2H2O
Table 1. Elemental analyses
Compound
Ni(Co)
I
II
III
IV
V
VI
VII
VIII
20
[Ni(en)2(mnt)]
[Ni(1,2-dap)2(mnt)].H2O
[Ni(n-phen)(mnt)]
[Ni2(4,4’-bpy)4(mnt)2Cl(H2O)2].2H2O
[Ni(dpp)(mnt)].H2O
[Co(phen)(mnt)].H2O
[Co(dppe)(mnt)].2H2O
(Me3PhN)2[Ni(mnt)2]
18.4/18.0
16.1/15.9
13.8/13.4
10.4/10.2
9.3/9.4
14.8/14.6
9.3/9.0
9.6/10.0
C
30.1/29.7
32.9/33.2
45.3/46.0
51.0/50.2
59.2/59.3
48.3/48.0
56.9/56.7
51.1/51.2
Calcd./found %
H
N
5.0/4.7
6.1/5.6
1.7/2.1
3.6/3.3
4.5/4.2
2.5/2.6
4.4/3.8
4.6/4.3
26.3/26.8
23.0/22.9
16.5/16.7
14.9/14.3
4.5/4.5
14.1/13.9
4.4/4.5
13.7/13.6
P
S
–
–
–
–
9.8/9.5
–
9.8/9.5
–
20.1/19.3
17.6/17.6
15.1/15.4
11.3/10.7
10.1/9.1
16.1/15.3
10.1/10.6
21.0/21.4
Table 2. Physico-chemical properties of synthesized complexes
Cmpd.
I
II
III
IV
V
VI
VII
VIII
Color
lMa
meff /BM
[Scm2/mol] (295 K) n(C – S)
orange
orange
brown
brown
brown
green
brown
orange
26.5
29.1
28.2
–
–
22.8
–
–
2.41
2.43
2.13
3.15b
diam.
3.19
2.16
diam.
834 w
832 m
828 m, 844 s
830 s, 858 m
816 s, 842 s
844 s
828 m, 858 s
842 w, 868 m
IR [cm–1]
d(C – P) n(N – H) n(C – Har)
1250 w
1249 m
760 s
742 m
1100 m
1100 s
766 m
UV/VIS
[.103 cm–1]
19.0
18.0
17.0
19.0
18.0
15.0
15.0
12.0
26.0
21.0
–
25.0
–
22.0
20.0
21.0
30.0
27.0
30.0
30.0
27.5
37.0
36.0
34.0
36.0
26.0 37.0
a
Measured in dimethylformamide;
2.23 BM per one central atom
The conductivity measurements for IV, V, VII, VIII were not performed due to low solubility.
b
B) Cobalt complexes
Samples VI, VII are paramagnetic with meff = 3.19 and 2.16 BM. From this fact and
from stoichiometry it follows that both complexes are probably square planar (for
tetragonal coordination, three unpaired electron are necessary), although the first
value of meff seems to be very high (but a similar case was recently described in the
literature16). This assumption is supported also by the results of electron spectroscopy;
the conductivity measurements were performed only for VI (non-electrolyte) due to
low solubility.
C) X-ray crystallography
The crystal and molecular structure of (Me3PhN)2[Ni(mnt)2] (VIII) (see Fig. 2)
was solved by heavy atom method and refined anisotropically by the full-matrix leastsquare procedure on F2; the hydrogen atoms were refined isotropically. The most
important crystallographic parameters are given in Table 3; the selected bond distances and angles are collected in Table 4, possible hydrogen bonds (according17) in
Table 5.
It was confirmed that the coordination polyhedron of nickel is a square; the
deviations of C1, C2 carbon atoms of ring from NiS4 plane are less than 0.03 Å and
also carbon and nitrogen atoms from cyanide group C3, C4, N1, N2 are approximately
co-planar to this plane (deviations less than 0.1 Å). The calculated bond distances and
angles in the chromophore are in good accordance with the values obtained for similar
structures in the literature18, 19. The Me3PhN+ group is out of the coordination sphere
of central atom; three possible hydrogen bonds between C8, C11 and C12 of this
group and nitrogen atoms N1, N2 from cyanide were found in the structure.
21
Fig. 2. Molecule of (Me3PhN)2[Ni(mnt)2] with the atom numbering scheme. Thermal ellipsoids are drawn
at 40 % probability level.
22
Table 3. Crystal data and structure refinement for (Me3PhN)2[Ni(mnt)2]
Empirical formula
Formula weight
Temperature
Wavelength
Crystal system, space group
Unit cell dimensions
Volume
Z, Calculated density
Absorption coefficient
F(000)
Crystal size
Theta range for data collection
Index ranges
Reflections collected/unique
Completeness to 2q = 28.37°
Max. and min. transmission
Refinement method
Data/restraints/parameters
2
Goodness-of-fit on F
Final R indices [I>2s(I)]
R indices (all data)
Extinction coefficient
Largest diff. peak and hole
C26H28N6NiS4
611.49
150(2) K
0.71073 Å
–
triclinic, P 1
a = 9.132(2) Å, a = 105.45(3)°
b = 9.411(2) Å, b = 94.16(3)°
c = 10.815(2) Å, g = 118.99(3)°
3
760.9(3) Å
3
1, 1.335 Mg/m
–1
0.937 mm
318
0.30 × 0.25 × 0.25 mm
3.43 to 28.37°
–12 £ h £ 12, –12 £ k £ 6, –13 £ l £ 14
5758/3288 [R(int) = 0.0217]
85.9 %
0.7994 and 0.7663
2
Full-matrix least-squares on F
3288/0/170
0.994
R1 = 0.0362, wR2 = 0.0926
R1 = 0.0499, wR2 = 0.0982
0.026(3)
–3
0.255 and –0.295 e.Å
Table 4. Selected bond lengths [Å] and angles [°] for (Me3PhN)2[Ni(mnt)2]
Ni(1)-S(1)
Ni(1)-S(2)
S(1)-C(2)#1
S(2)-C(1)
C(1)-C(2)
C(1)-C(3)
C(2)-C(4)
C(3)-N(1)
C(4)-N(2)
2.1616(8)
2.1679(10)
1.733(3)
1.731(2)
1.347(4)
1.429(4)
1.435(3)
1.136(3)
1.132(3)
S(1)-Ni(1)-S(2)
S(1)#1-Ni(1)-S(2)
C(2)#1-S(1)-Ni(1)
C(1)-S(2)-Ni(1)
C(2)-C(1)-S(2)
C(1)-C(2)-S(1)#1
N(1)-C(3)-C(1)
N(2)-C(4)-C(2)
88.14(3)
91.86(3)
103.37(9)
103.51(9)
120.32(18)
120.90(18)
178.7(3)
177.3(3)
Symmetry transformations used to generate equivalent atoms:
#1 –x+1, –y+1, –z+1
23
Table 5. Possible hydrogen bonds for (Me3PhN)2[Ni(mnt)2]
Donor-H
Donor...Acceptor
H...Acceptor
Donor-H......Acceptor
C8 – H8
1.082(.014)
1.080
C11 – H11A
.995(.018)
1.080
C12 – H12C
1.053(.023)
1.080
C8....N1 (1)
3.438(.028)
H8...N1 (1)
2.568(.020)
2.570
H11A...N2 (2)
2.640(.047)
2.569
H12C...N2 (2)
2.476(.006)
2.451
C8 – H8...N1 (1)
136.81(.23)
136.84 (**)
C11 – H11A...N2 (2)
148.07(.25)
147.07 (**)
C12-H12C...N2 (2)
157.09(.25)
156.84 (**)
C11 ....N2 (2)
3.525(.053)
C12 ....N2 (2)
3.470(.009)
(**) Values normalized following G. A. Jeffrey & L. Lewis, Carbohydr. Res. (1978). 60, 179;
R. Taylor, O. Kennard, Acta Cryst. (1983). B39, 133.
Equivalent positions:
(1) –x+2, –y+2, –z+2
(2) x+1, +y, +z–1
Supplementary data
Material involving structure data has been deposited in the Cambridge Crystallografic Data Centre, Registry No. CCDC 192838. The data are available at
[email protected].
Acknowledgement
Authors thank the Grant Agency of the Czech Republic (grant project
No. 203/02/0436) for financial support.
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Fac. rer. nat. 2002
Chemica 41, 17–25
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