Electrochemical synthesis and characterization of cobalt(II), cobalt(III), and nickel(II) complexes with pyrimidine-2-thionato ligands

Article abstract of DOI:10.1002/zaac.200600387

The electrochemical oxidation of anodic metal (cobalt and nickel) in acetonitrile solutions of the appropriate pyrimidine-2-thione derivatives (RpymSH, where R = 4-CF₃, 4,6-CF₃Me, 4,6-MePh, 4,6-CF ₃Ph, 4,6-Ph₂) afforded complexes of composition [M(RpymS)₂], M = Co, Ni or [Co(RpymS)₃]. When 2,2′-bipyridine (bipy) or 1,10-phenanthroline (phen) was added to the electrolytic cell, adducts of cobalt(II) and nickel(II) compounds with these coligands were obtained: [M(RpymS)₂bipy] and [M(RpymS) ₂phen]. All of the compounds were characterized by microanalysis, electronic, vibrational spectroscopy and FAB mass spectrometry, and, in the cases of the compounds [Co(RpymS)₃], by ¹H and ¹³C, NMR spectroscopy. The compound [Co(4-CF₃pymS) ₃] was also characterized by X-ray diffraction. The crystal structure consists of monomeric molecules in which the central CoS₃N ₃ unit has a slightly distorted octahedral coordination with the ligands adopting a meridional disposition.

Full text of DOI:10.1002/zaac.200600387

DOI: 10.1002/zaac.200600387
Electrochemical Synthesis and Characterization of Cobalt(II), Cobalt(III), and
Nickel(II) Complexes with Pyrimidine-2-thionato Ligands
a
a,
a
a
a
b
´
´
´
A. Rodrıguez , J. A. Garcıa-Vazquez *, J. Romero , A. Sousa-Pedrares , A. Sousa , and J. Castro
a
´
´
Santiago de Compostela/Spain, Departamento de Quımica Inorganica, Universidad de Santiago de Compostela
b
´
´
Vigo/Spain, Departamento de Quımica Inorganica, Universidad de Vigo
Received December 21st, 2006.
Dedicated to Professor Joachim Strähle on the Occasion of his 70th Birthday
Abstract. The electrochemical oxidation of anodic metal (cobalt
and nickel) in acetonitrile solutions of the appropriate pyrimidine-
2-thione derivatives (RpymSH, where R ϭ 4-CF3, 4,6-CF3Me, 4,6-
MePh, 4,6-CF3Ph, 4,6-Ph2) afforded complexes of composition
[M(RpymS)2], M ϭ Co, Ni or [Co(RpymS)3]. When 2,2Ј-bipyridine
(bipy) or 1,10-phenanthroline (phen) was added to the electrolytic
cell, adducts of cobalt(II) and nickel(II) compounds with these coli-
gands were obtained: [M(RpymS)2bipy] and [M(RpymS)2phen].
All of the compounds were characterized by microanalysis, elec-
tronic, vibrational spectroscopy and FAB mass spectrometry, and,
in the cases of the compounds [Co(RpymS)3], by 1H and 13C, NMR
spectroscopy. The compound [Co(4-CF3pymS)3] was also characte-
rized by X-ray diffraction. The crystal structure consists of mono-
meric molecules in which the central CoS3N3 unit has a slightly
distorted octahedral coordination with the ligands adopting a meri-
dional disposition.
Keywords: Electrochemical synthesis; Cobalt and Nickel complexes;
Pyrimidine-thionate; Crystal structure
1 Introduction
Much of the interest in metal-sulfur chemistry results from
the potential relevance of the resulting compounds to active
sites in metalenzymes and also to their ability to adopt va-
rious nuclearities of significant structural complexity [1Ϫ3].
This latter characteristic is a consequence of the tendency
of thiolates to bridge metal centres. However, the aggrega-
tion process may be limited by providing steric constraints
through appropriate ligand design or the introduction of
coligands to block a number of coordination sites [4].
As part of our continued interest in heterocyclic thione
compounds, we report here the electrochemical synthesis of
cobalt and nickel complexes with pyrimidine-2-thione li-
gands (Scheme 1) using an electrochemical procedure in
which the metal is the anode of a cell containing the ligand
in solution. The electrochemical procedure used in this
work is a simple and successful route for the synthesis of
metal complexes with heterocyclic thiones [5]. In a similar
way to other heterocyclic thiones, such as pyridine-2-thione,
these ligands are very versatile in terms of their coordina-
tion modes; they can act as neutral monodentate systems
Scheme 1
through sulfur (η1-S) [6]; through one of the nitrogen atoms
(η1-N) [7]; as a neutral bridging ligand through sulfur (µ2-
S) [8]; a neutral ϪSN chelating ligand [9]; anionic S-mono-
dentate (η1-S) [10]; an ϪN,S chelating ligand [11]; a bi-
nuclear bridging ligand µ2-(S,N)(η1-S, η1-N) [12] or µ2-
(S,N)(η2-S) [13]; a binuclear triple bridging ligand µ2-
(S,N)(η2-S, η1-N) [14] or µ2-(S,N)(η2-N,S, NЈ, η2-S) [15] or
a trinuclear triple bridging ligand µ3-(S,N)(η2-S, η1-N) [16].
Moreover, the presence in the ligands used in this work of
different substituents on the pyrimidine ring (Scheme 1) al-
lows the possibility of investigating whether the nature, po-
sition and number of substitutents has any influence on the
coordinative behaviour of these ligands and, consequently,
on the structure of the corresponding metal-heterocyclic
thionate complexes. In addition, we are interested in incor-
porating coligands such as 1,10-phenanthroline and 2,2Ј-
bipyridine into the coordination sphere of cobalt and nickel
to assess whether its presence can lead to novel structures.
´
´
´
´
* Professor Dr. Jose Arturo Garcıa-Vazquez
´
Departamento de Quımica Inorganica
Universidad de Santiago de Compostela
E-15782-Santiago de Compostela/ Spain
Fax: 981547103
E-mail: qijagv@usc.es
Z. Anorg. Allg. Chem. 2007, 633, 763Ϫ770
 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
763

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A. Rodrıguez, J. A. Garcıa-Vazquez, J. Romero, A. Sousa-Pedrares, A. Sousa, J. Castro
Table 1 Analytical data for cobalt and nickel complexes. Theoretical values are given in brackets.
Complex
Colour
M. W.
%C
(g/mol)
%N
%H
%S
Yield/%
[Co(4-CF3pymS)3]
[Co(4,6-CF3MepymS)3]
[Co(4,6-MePhpymS)2]
Brown/Green
Green
Pale brown
Brown
Pale brown
Grey
Pale pink
Brown
Orange
Brown
Brown
Brown
Dark green
Brown
Brown
Brown
Brown
Green
Pale green
Brown
Brown
Brown
Brown
596.35
638.43
461.46
635.67
659.69
569.41
725.59
749.04
585.61
759.81
765.82
445.02
601.21
625.23
461.22
617.10
641.10
569.16
725.35
749.37
587.08
741.55
767.15
30.02(30.21)
33.79(33.86)
56.79(57.26)
60.20(60.46)
61.12(61.90)
46.34(46.41)
52.06(52.97)
53.91(54.47)
64.28(65.63)
66.09(66.39)
68.14(69.01)
32.8(32.39)
44.26(43.95)
45.38(46.11)
58.98(57.29)
62.60(62.23)
63.24(63.64)
47.42(46.43)
52.89(52.99)
53.31(54.50)
65.08(65.41)
67,84(68.03)
68.95(68.83)
13.91(14.09)
13.02(13.16)
12.26(12.14)
13.52(13.22)
12.46(12.74)
10.16(9.84)
11.88(11.58)
11.43(11.22)
9.38(9.57)
9.65(11.06)
10.94(10.97)
11.72(12.59)
14.10(13.98)
12.90(13.44)
13.10(12.15)
12.96(13.62)
12.51(13.11)
9.97(9.84)
1.02(1.01)
1.75(1.89)
3.97(3.97)
4.23(4.44)
4.78(4.28)
3.12(2.12)
3.51(2.78)
2.27(2.69)
3.51(3.79)
4.79(4.25)
4.27(3.95)
2.16(1.81)
2.86(2.68)
2.38(2.58)
4.57(3.93)
4.12(4.25)
4.00(4.09)
3.39(2.13)
3.73(2.78)
3.71(2.69)
3.97(4.12)
4.32(4.08)
4.64(4.20)
15.98(16.13)
15.27(15.07)
13.58(13.89)
9.81(10.09)
9.82(9.72)
11.16(11.26)
8.23(8.84)
8.56(8.54)
10.82(10.95)
8.36(8.44)
79
58
61
70
64
74
63
70
68
70
54
57
69
59
53
55
67
79
84
93
76
66
70
[Co(4,6-MePhpymS)2bipy](H2O)
[Co(4,6-MePhpymS)2phen](H2O)
[Co(4,6-CF3PhpymS)2]
[Co(4,6-CF3PhpymS)2bipy]
[Co(4,6-CF3PhpymS)2phen]
[Co(4,6-Ph2pymS)2]
[Co(4,6-Ph2pymS)2bipy](H2O)
[Co(4,6-Ph2pymS)2phen]
[Ni(4,6-CF3MepymS)2]
[Ni(4,6-CF3MepymS)2bipy]
[Ni(4,6-CF3MepymS)2phen]
[Ni(4,6-MePhpymS)2]
[Ni(4,6-MePhpymS)2bipy]
[Ni(4,6-MePhpymS)2phen]
[Ni(4,6-CF3PhpymS)2]
[Ni(4,6-CF3PhpymS)2bipy]
[Ni(4,6-CF3PhpymS)2phen]
[Ni(4,6-Ph2pymS)2]
8.36(8.37)
14.17(14.41)
10.37(10.67)
10.08(10.26)
13.70(13.90)
9.73(10.36)
9.53(9.97)
10.87(11.27)
8.72(8.84)
8.95(8.56)
11.06(11.59)
11.51(11.21)
9.28(9.54)
10.27(11.33)
10.85(10.95)
10.25(10.89)
8.31(8.65)
8.51(8.34)
[Ni(4,6-Ph2pymS)bipy]
[Ni(4,6-Ph2pymS)2phen]
[M(RpymS)2] (M ϭ Co, Ni); in these compounds an addi-
tional neutral ligand is not incorporated into the coordina-
tion sphere of the metal atom.
The experimental conditions for the synthesis of these
compounds are summarized in Table 2.
The Electrochemical Efficiency values (Table 2) Ϫ defi-
ned as the number of moles of metal dissolved per Faraday
of charge Ϫ are approximately 0.5 mol.FϪ1 regardless of
whether the metal atom in the complex is in oxidation state
II or III. This observation indicates anodic oxidation pro-
cesses leading to the production of CoII or NiII species. This
fact, along with the evolution of hydrogen at the cathode,
is compatible with the following equations:
2 Results and Discussion
The anodic oxidation of cobalt and nickel in an electroche-
mical cell containing solutions of different ligands RpymSH
in acetonitrile gave a series of complexes. The analytical
data for these compounds are given in Table 1 and are con-
sistent with the formulae [M(RpymS)2] (M ϭ Co, Ni) or
[Co(RpymS)3], depending on the nature of the ligand. In
these formulae RpymS represents the anion of the corre-
sponding heterocyclic thione. The compounds are air stable
and moderately soluble in organic solvents such as dichlo-
romethane and ethanol.
The presence in the pyrimidine ring of substituents that
do not cause too great a steric impediment, e.g. 4-trifluoro-
methylpyrimidine-2-thione and 4,6-methyltrifluoromethyl-
pyrimidine-2-thione, leads to CoIII complexes of the type
[Co(RpymS)3]. On the other hand, the use of ligands
with greater steric hindrance, such as 4,6-methylphenylpyri-
Cathode: 2 RpymSH ϩ 2eϪ Ǟ 2 RpymSϪ ϩ H2
Anode: M Ǟ M2ϩ ϩ 2eϪ
Overall M ϩ 2 RpymSH Ǟ [M(RpymS)2] ϩ H2
Overall M ϩ 2 RpymSH ϩ L Ǟ [M(RpymS)2L] ϩ H2
L ϭ bipy or phen
midine-2-thione,
4,6-phenyltrifluoromethylpyrimidine-2-
thione and 4,6-diphenylpyrimidine-2-thione, gave CoII com-
plexes with the general formula [Co(RpmyS)2]. This is pro-
bably due to the greater steric hindrance produced by the
two substituents on the ligand in positions close to the do-
nor atoms.
In those cases where the final product is a compound in
which the cobalt atom is in oxidation state III, one can
envisage a subsequent oxidation in solution of the initial
cobalt(II) compound by another RpymSH molecule in or-
der to generate the final species.
The presence in the electrochemical cell of additional ni-
trogen ligands like 2,2Ј-bipyridine (bipy) or 1,10-phenan-
throline (phen) generally gave mixed CoII and NiII comple-
xes. The analytical data of these compounds (Table 1) are
consistent with the formulae [M(RpymS)2bipy] and
[M(RpymS)2phen], respectively. However, in some cases the
presence of these additional ligands in the electrochemical
cell did not lead to the formation of mixed complexes and
the products had the composition [Co(RpymS)3] or
1
[Co(RpymS)2] ϩ RpymSH Ǟ [Co(RpymS)3] ϩ /2 H2
This type of behaviour has already been observed in the
synthesis of cobalt(III) compounds with other ligands [17].
764
www.zaac.wiley-vch.de
 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2007, 763Ϫ770

Cobalt(II), Cobalt(III), and Nickel(II) Complexes with Pyrimidine-2-thionato Ligands
Table 2 Experimental conditions for the electrochemical synthesis of cobalt and nickel complexes.
Reaction
Ligand
(mg)
Coligand
(mg)a
Metal
dissolved (mg)
Time
(h)
Initial
Electrochemical
Efficiency (Ef)
Voltaje(V)b
Co ϩ 4-CF3pymSH
Co ϩ 4,6-CF3MepymSH
Co ϩ 4,6-MePhpymSH
150
200
150
150
150
100
100
100
150
150
150
200
200
007
150
150
150
100
100
100
150
150
150
Ϫ
Ϫ
Ϫ
17
25
21
20
20
12
11
11
17
15
16
32
28
27
19
21
22
12
11
11
17
18
11
1.48
2.09
1.90
1.90
1.90
1.05
1.05
1.05
1.52
1.52
1.52
2.76
2.50
2.50
1.90
1.90
1.90
1.05
1.05
1.05
1.50
1.52
1.05
10
15
8
24
8
8
10
8
5
6
7
23
37
29
5
10
7
0.52
0.54
0.50
0.48
0.48
0.52
0.46
0.46
0.51
0.45
0.48
0.53
0.51
0.49
0.46
0.50
0.52
0.51
0.48
0.47
0.51
0.54
0.48
Co ϩ 4,6-MePhpymSH ϩ bipy
Co ϩ 4,6-MePhpymSH ϩ phen
Co ϩ 4,6-CF3PhpymSH
Co ϩ 4,6-CF3PhpymSH ϩ bipy
Co ϩ 4,6-CF3PhpymSH ϩ phen
Co ϩ 4,6-Ph2pymSH
Co ϩ 4,6-Ph2pymSH ϩ bipy
Co ϩ 4,6-Ph2pymSH ϩ phen
Ni ϩ 4,6-CF3MepymSH
Ni ϩ 4,6-CF3MepymSH ϩ bipy
Ni ϩ 4,6-CF3MepymSH ϩ phen2
Ni ϩ 4,6-MePhpymSH
Ni ϩ 4,6-MePhpymSH ϩ bipy
Ni ϩ 4,6-MePhpymSH ϩ phen
Ni ϩ 4,6-CF3PhpymSH
Ni ϩ 4,6-CF3PhpymSH ϩ bipy
Ni ϩ 4,6-CF3PhpymSH ϩ phen
Ni ϩ 4,6-Ph2pymSH
57
73
Ϫ
30
35
Ϫ
45
56
Ϫ
60
50
Ϫ
57
73
Ϫ
30
35
Ϫ
8
8
8
5
7
6
Ni ϩ 4,6-Ph2pymSH ϩ bipy
Ni ϩ 4,6-Ph2pymSH ϩ phen
44
56
a Plus [NEt4]ClO4 (ca. 20 mg).
b Voltage to produce current of 10 mA.
2.1 Description of the molecular structure of [Co(4-
CF3-pymS)3]
Table 3 Summary of Crystal Data for [Co(4-CF3pymS)3].
Empirical Formula
Formula weight
Temperature
Colour; Habit
Crystal System
Space Group
C15H6CoF9N6S3
596,37
293.10 K
green, prismatic
monoclinic
P21/c
The crystal structure of the complex [Co(4-CF3-pymS)3] is
shown in Figure 1 along with the atom numbering scheme.
Crystallographic data and a selection of bond angles and
distances for this complex are given in Tables 3 and 4.
There are three independent molecules in the asymmetric
unit and the angles and distances differ slightly between
these three molecules (Table 4).
˚
Unit Cell Dimensions
a ϭ 23.0701(12) A
˚
b ϭ 11.1850(6) A
˚
c ϭ 25, 8817(13) A
β ϭ 96.8860(10)°
6630.3(6)
3
˚
Volume, A
It can be seen from Figure 1 that the compound consists
of discrete molecules in which the metal atom is coordi-
nated to three monoanionic ligands in a chelate fashion
through one of the nitrogen atoms and the sulfur atom to
give an octahedral CoN3S3 environment around the cobalt
centre.
The arrangement of the nitrogen and sulfur atoms
around the metal atom is such that the meridional isomer
is obtained. It can be seen that this disposition is maintai-
ned in solution, a situation confirmed by 1H and 13C NMR
spectroscopy. This isomer is also found in other metal tri-
schelates described in the literature, e.g. the pyridine-2-thio-
nates [Co(pyS)3] [18] and [Co(3-Me3SipyS)3] [19], but is dif-
ferent to that observed for the pyrimidine derivative
[Co(4,6-Me2-pymS)3] [20] in which a facial conformation
is found.
Z
12
dcalc, g cmϪ3
Absorption coefficient
F(000)
1.792 g cmϪ3
1.152 mmϪ1
3528
Crystal size /mm
0.54 x 0.37 x 0.17
0.71073
4.871
1.72 to 28.00 deg.
Ϫ30ՅhՅ23
Ϫ14ՅkՅ14
˚
λ, A (MoKα radiation)
ν (MoKα), mmϪ1
Theta range for data collection
Index ranges
Ϫ34ՅlՅ26
35543
Reflections collected
Independent reflections
Max. and min. Transmission
Data/ restraints / parameters
Goodness of fit on F2
Final R indices [I >2sigma(I)]
R indices (all data)
14569 (Rint ϭ 0.0133)
0.8283 and 0.5752
14569/ 0 / 919
0.883
R1 ϭ 0.0571, wR2 ϭ 0.1253
R1 ϭ 0.1404, wR2 ϭ 0.1478
Ϫ3
˚
Largest diff.peak and hole
0.860 and Ϫ0.579 e.A
In molecule 1, as in the other two molecules, the equato-
rial plane is formed by one of the nitrogen atoms from one
of the heterocyclic thiones and three sulfur atoms from the
three pyrimidine-2-thionate ligands Ϫ although these four
atoms are not exactly coplanar. If we consider the best
plane that includes these four atoms, N(31) and S(11) oc-
cupy trans positions and are located below the plane at
˚
Ϫ0.1548 and Ϫ0.2314 A, respectively, while the S(12) and
S(13) atoms are located above the plane by ϩ0.1677 and
˚
ϩ0.2185 A, respectively. The cobalt atom is very close to
the aforementioned plane and is only 0.005 A below it.
These deviations from planarity are evident in the bond
angles around the metal atom; N(31)ϪCoϪS(11),
˚
Z. Anorg. Allg. Chem. 2007, 763Ϫ770
 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
765

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A. Rodrıguez, J. A. Garcıa-Vazquez, J. Romero, A. Sousa-Pedrares, A. Sousa, J. Castro
try is undoubtedly the small size of the chelate angle, which
influences coordination of the different ligands to the co-
balt atom. The average value of the chelate angles
NϪCoϪS is 72.45(13)°. This value is similar to that found
in other complexes in which the ligand coordinates in a bi-
dentate fashion to give a five-membered ring.
Table 4 Bond lengths and angles for [Co(4-CF3pymS)3]
Co(1)-N(11)
Co(1)-N(31)
Co(1)-S(13)
S(11)-C(11)
S(13)-C(31)
Co(2)-N(41)
Co(2)-N(61)
Co(2)-S(23)
S(21)-C(41)
S(23)-C(61)
Co(3)-N(71)
Co(3)-S(31)
Co(3)-S(33)
S(32)-C(71)
N(71)-C(75)
1.907(4)
1.951(4)
2.2990(14)
1.714(5)
1.724(5)
1.897(4)
1.943(4)
2.293(2)
1.720(5)
1.709(5)
1.916(4)
2.264(2)
2.303(2)
1.712(5)
1.326(6)
Co(1)-N(21)
Co(1)-S(11)
Co(1)-S(12)
S(12)-C(21)
N(11)-C(15)
Co(2)-N(51)
Co(2)-S(21)
Co(2)-S(22)
S(22)-C(51)
Co(3)-N(91)
Co(3)-N(81)
Co(3)-S(32)
S(31)-C(91)
S(33)-C(81)
1.910(4)
2.283(2)
2.302(2)
1.719(5)
1.308(6)
1.917(4)
2.281(2)
2.304(2)
1.726(5)
1.904(4)
1.936(4)
2.2813(14)
1.719(5)
1.716(5)
The values of the three CoϪN bond distances for each
of the molecules are slightly different [1.907(4), 1.910(4) and
˚
1.951(4) A], with the longest distance corresponding to the
CoϪN(31) bond, which is in the trans position with respect
to the CoϪS(11) bond. The average value for this bond,
III
˚
1.923(4) A, is very similar to those found in a series of Co
complexes that are octahedrally coordinated by the hetero-
cyclic thiones pyridine-2-thione and pyrimidine-2-thione.
The value described above is very similar to those found
N(11)-Co(1)-N(21)
N(21)-Co(1)-N(31)
N(21)-Co(1)-S(11)
N(11)-Co(1)-S(13)
N(31)-Co(1)-S(13)
N(11)-Co(1)-S(12)
N(31)-Co(1)-S(12)
S(13)-Co(1)-S(12)
N(41)-Co(2)-N(61)
N(41)-Co(2)-S(21)
N(61)-Co(2)-S(21)
N(51)-Co(2)-S(23)
S(21)-Co(2)-S(23)
N(51)-Co(2)-S(22)
S(21)-Co(2)-S(22)
C(41)-S(21)-Co(2)
N(91)-Co(3)-N(81)
N(91)-Co(3)-S(31)
N(81)-Co(3)-S(31)
N(71)-Co(3)-S(32)
S(31)-Co(3)-S(32)
N(71)-Co(3)-S(33)
S(31)-Co(3)-S(33)
168.6(2)
94.3(2)
N(11)-Co(1)-N(31)
N(11)-Co(1)-S(11)
N(31)-Co(1)-S(11)
N(21)-Co(1)-S(13)
S(11)-Co(1)-S(13)
N(21)-Co(1)-S(12)
S(11)-Co(1)-S(12)
N(41)-Co(2)-N(51)
N(51)-Co(2)-N(61)
N(51)-Co(2)-S(21)
N(41)-Co(2)-S(23)
N(61)-Co(2)-S(23)
N(41)-Co(2)-S(22)
N(61)-Co(2)-S(22)
S(23)-Co(2)-S(22)
N(91)-Co(3)-N(71)
N(71)-Co(3)-N(81)
N(71)-Co(3)-S(31)
N(91)-Co(3)-S(32)
N(81)-Co(3)-S(32)
N(91)-Co(3)-S(33)
N(81)-Co(3)-S(33)
S(32)-Co(3)-S(33)
95.3(2)
72.68(13)
161.54(12)
96.92(13)
93.58(6)
72.25(12)
97.93(6)
167.7(2)
95.3(2)
97.74(11)
93.15(12)
72.36(12)
99.78(13)
95.60(12)
163.13(6)
165.0(2)
93.8(2)
99.38(12)
91.83(12)
72.42(12)
100.29(12)
97.99(12)
165.30(6)
94.9(2)
73.12(12)
164.77(12)
96.41(12)
98.38(6)
72.47(12)
95.74(6)
77.5(2)
˚
in [Co(pyS)3], 1.912(6)Ϫ1.923(6) A, [Co(3-Me3SipyS)3],
˚
1.86(1)Ϫ1.91(1) A
and
[Co(4,6-pymS)3],
1.975(5)Ϫ
˚
1.986(5) A (pyS ϭ pyridine-2-thionate; 3-Me3SipyS ϭ 3-tri-
methylsilylpyridine-2-thionate).
The CoϪS bond distances are also different to one ano-
˚
ther and are in the range 2.283(2)Ϫ2.302(2) A, with the
shortest distance in each molecule corresponding to the
bond trans with respect to the nitrogen atom. However,
these values are similar to those observed in the aforemen-
˚
tioned trischelates; 2.292(3)Ϫ2.313(3) A in [Co(pyS)3],
97.5(2)
˚
˚
2.241(8)Ϫ2.315(8) A
in
[Co(3-Me3SipyS)3]
and
73.06(13)
165.64(12)
72.87(13)
95.80(6)
96.71(13)
97.33(6)
97.48(14)
96.09(12)
95.97(12)
96.08(12)
72.48(12)
164.22(6)
2.252(2)Ϫ2.269(2) A in [Co(4,6-pymS)3].
The bidentate 4-trifluoropyrimidine-2-thionate ligands
are planar, within the margins of error, with a maximum
˚
deviation of 0.03 A. However, as mentioned above, the three
independent molecules in the unit cell are not completely
equivalent. For example, the sulfur atoms in molecule 1 are
essentially in the plane of the pyrimidine ring to which they
are bonded, with the maximum deviation of the sulfur
atoms from the best plane of the pyrimidine being
S(12)ϪCoϪS(13) and N(11)ϪCoϪN(21) have values that
are significantly different to the ideal value of 180°
[161.54(13), 165.30(6) and 168.6(2)°, respectively]. One of
the main causes of this distortion from the regular geome-
˚
0.028(6) A. The cobalt atom is in the plane of one of these
Figure 1 Molecular structure of [Co(4-CF3-pymS)3]
766
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Z. Anorg. Allg. Chem. 2007, 763Ϫ770

Cobalt(II), Cobalt(III), and Nickel(II) Complexes with Pyrimidine-2-thionato Ligands
˚
Table 5 Magnetic and UV-Vis. Spectroscopic data for CoII
single complexes.
rings [0.011(6) A] but is out of the planes of the other two
˚
rings, with deviations of ϩ0.273(6) and Ϫ0.124(6) A. The
planes of these rings are almost perpendicular to one ano-
ther, with interplanar angles of 82.2(1), 82.8(1) and 77.2(1)°.
However, in the case of molecule 2 only one of the sulfur
atoms is located in the plane of the pyrimidine ring to which
Complex
4A2
Ǟ
4T1 (F) 4A2
)
Ǟ
4T1 (P) 4A2
)
Ǟ
4T2
µ
ν2 (cmϪ1
ν3 (cmϪ1
ν1 (calc.)(cmϪ1
)
(BM)
[Co(4,6-Me2,5-EtpymS)2] 8650, 9852
14880
15720
15150
16390
5835
6046
5827
5463
4.45
4.35
4.16
4.65
[Co(4,6-Ph2pymS)2]
[Co(4,6-PhMepymS)2]
[Co(4,6-CF3PhpymS)2]
9671
8665, 9940
9140
˚
it is bonded [0.025(6) A], with the other two sulfur atoms
displaced from the plane of the ring to which they are
˚
bonded [0.081(7) and 0.104(6) A]. The cobalt centre, in a
similar way to that in molecule 1, is in the plane of one of
˚
Table 6 Magnetic and UV-Vis. Spectroscopic data for CoII
mixed complexes.
the rings [0.043(6) A] and out of the planes of the other
˚
two [Ϫ0.077(7) and 0.124(6) A]. The interplanar angles are
closer to perpendicular than those in molecule 1, with va-
lues of 85.3(1), 79.9(1) and 89.4(1)°. In molecule 3, two of
the sulfur atoms are in the plane of the ring to which they
4
4
4
4
4
Complex
4T1g(F) Ǟ T2g T1g(F) Ǟ A2g T1g(F) Ǟ T1g(P) µ
(ν1) (cmϪ1
)
(ν2) (cmϪ1
)
(ν3) (cmϪ1
)
(MB)
˚
are bonded [Ϫ0.001(1) and Ϫ0.021(7) A] and the other is
[Co(4,6-Ph2pymS)2bipy]
[Co(4,6Ph2pymS)2phen]
[Co(4,6-PhMepymS)2bipy] 10000
[Co(4,6-PhMepymS)2phen] 9750
9520
8900
15625
15528
15625
15430
832,
21230
20790
21413
21230
20534
21270
4.98
4.64
5.02
4.92
5.33
4.70
˚
out of the plane [0.070(7) A]. The Co(3) atom is in the plane
˚
of one of the ligands [0.043(6) A] and out of the planes of
˚
the other two [Ϫ0.065(7) and 0.099(7) A]. The angles bet-
[Co(4,6-CF3PhpymS)bipy] 78901592318
[Co(4,6-CF3PhpymS)phen] 8820
ween these planes are 82.9(2), 84.2(2) and 87.1(1)°. In all
three molecules the four-membered chelate rings (Co, S, N
and C) are essentially planar, with the maximum deviation
Electronic spectra and magnetic moments
˚
with respect to the best plane being 0.042(2) A.
˚
The diffuse electronic reflectance spectra of the CoIII com-
plexes contain bands at 15150 cmϪ1 and 20870 cmϪ1 for
[Co(4-CF3pymS)3] and at 15870 and 20080 cmϪ1 for
[Co(4,6-MeCF3pymS)3]. These bands are characteristic of
low spin CoIII complexes in which the metal is in an octahe-
The SϪC [1.709(5)Ϫ1.726(5) A] bond distances in the py-
rimidine-2-thionate ligands are intermediate between the
values observed in the free ligands 4,6-dimethylpyrimidine-
2-thione [21] and 1-phenyl-4,6-dimethylpyrimidine-2-thione
˚
˚
[22] [1.692(2) A and 1.686(4) A, respectively], which exist in
the thione form in the solid state, and the values of
dral environment [29]. The first of these bands is attributed
˚
˚
1
1.781(2) A and 1.782(3) A found in the bis-pyrimidyl-2-2Ј-
disulfide [23] and bis-(4,6-dimethylpyrimidyl)-2,2Ј-disulfide
[24], which possess a simple CϪS bond; this suggests that
the ligand is coordinated in a form that is closer to the
pyrimidine-2-thionate than to the thione form.
to the transition A1g
A1g
Ǟ
1T1g and the second to the
Ǟ
1T1g transition. The magnetic moments of the
[CoL3] complexes show that these compounds are essenti-
ally diamagnetic and are consistent with their being low
spin d6 octahedral complexes.
The diffuse electronic reflectance spectra of complexes
(Table 5) with the formula [Co(RpymS)2] are characteristic
of species with the metal atom in a distorted tetrahedral
environment [29]. The spectra show two d-d bands, one
close to 15000 cmϪ1 and the other a broad multiplet bet-
ween 8600Ϫ9950 cmϪ1. The band in the visible region was
2.2 Spectroscopic data
IR Spectra
4
4
assigned to the transition A2 Ǟ T1(P) (ν3) and the multi-
component band in the infrared region to the transition 4A2
Ǟ 4T1(F) (ν2). The transition 4A2 Ǟ 4T2 (ν1) was not obser-
ved but its position was calculated (ca. 5800 cmϪ1) on the
basis of the band assigned as ν3 and taking ν2 as the centre
of the multiple band according to the procedure described
by Lever [29]. The magnetic moments of these compounds
are between 4.16 and 4.65 BM and this is in the expected
range for CoII complexes with tetrahedral environments.
In the mixed Co(II) complexes [Co(RpymS)2L] the solid
state ultraviolet spectra are characteristic of species with di-
storted octahedral environments around the metal atom
[29]. The complexes show three bands (Table 6). One of
these bands is in the region 9000 cmϪ1 and this can be assi-
The IR spectra of the complexes do not contain bands due
to ν(NϪH), which in the free ligands appear between 3200
and 3100 cmϪ1. This fact shows that deprotonation of the
NH group has occurred during the synthesis and, therefore,
that the ligand is coordinated in the thionato form.
This conclusion is supported by the shift to lower wave-
numbers of the strong bands for ν(CϭC) and ν(CϭN),
which appear at 1600Ϫ1550 and 1570Ϫ1525 cmϪ1 in the
free ligands, on going from the free ligands to the comple-
xes. In addition, bands attributable to the ring breathing
vibration at ca. 1000 and 630 cmϪ1 are observed. These
shifts provide evidence that the nitrogen atom is bound to
the metal atom [25, 26]. In addition, the mixed complexes
show bands that are typical for coordinated 2,2Ј-bipyridine
[27] (770 and 730 cmϪ1) and 1,10-phenanthroline [27, 28]
(1530Ϫ1505, 840 and 720 cmϪ1).
4
4
gned to the transition T1g(F) Ǟ T2g (ν1). Another band
is observed between 15000 and 16000 cmϪ1 [due to the
4
4T1g(F) Ǟ A2g transition (ν2)] and a third band is seen
Z. Anorg. Allg. Chem. 2007, 763Ϫ770
 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
767

´
´
´
A. Rodrıguez, J. A. Garcıa-Vazquez, J. Romero, A. Sousa-Pedrares, A. Sousa, J. Castro
Table 7 Magnetic and UV-Vis. Spectroscopic data for NiII single
Table 8 Magnetic andUV-Vis. Spectroscopic data or NiII mixed
complexes.
complexes.
3T1(F) Ǟ 3A2
(ν2)/cmϪ1
3T1(F) Ǟ 3T1(P) 3T1(F) Ǟ 3T2 µ (MB)
Complex
3A2g
Ǟ Ǟ Ǟ
3T1g(F) A2g 3T2g A2g 3T1g(P) µ (MB)
3
3
Complex
(ν3)/cmϪ1
(ν1)/calc. cmϪ1
(ν1)/cmϪ1
(ν2)/cmϪ1
(ν3)/cmϪ1
[Ni(4,6-CF3MepymS)2] 8780, 9960
[Ni(4,6-PhMepymS)2] 8800, 9900
[Ni(4,6-CF3PhpymS)2] 8626
15390
15150
15674, 17513
4320
4306
3957
4030
3.39
3.0
[Ni(4,6-CF3MepymS)2bipy] 10504
[Ni(4,6-CF3MepymS)2phen] 10406
16340
16103
15060
16100
15923
15640
15430
15620
21050
22173
23000
24875
21050
22170
23860
19900
2.98
3.17
2.98
2.93
3.05
[Ni(4,6-Ph2pymS)2bipy]
[Ni(4,6-Ph2pymS)2phen]
10000
10780
[Ni(4,6-Ph2pymS)2]
7645, 8779, 9794 13220, 14750
3.27
[Ni(4,6-PhMepymS)2bipy] 10764
[(Ni(4,6-PhMepymS)2phen] 10406
[Ni(4,6-CF3PhpymS)2bipy] 9940
[Ni(4,6-CF3PhpymS)2phen] 10000
between 20500 and 21500 cmϪ1 [assigned to the transition
4T1g(F) Ǟ 4T1g(P) (ν3)]. These bands are all consistent with
the metal atom being in an octahedral environment. The
magnetic moments of these complexes at room temperature
are in the range 4.64Ϫ5.33 BM. These values are as ex-
pected for octahedral CoII complexes (4.70Ϫ5.20 BM).
The diffuse reflectance spectra of all the homoleptic com-
plexes of nickelII (Table 7), [Ni(RpymS)2], are very similar
and show bands at around 9000 cmϪ1 (ν2) and 15000 cmϪ1
(ν3). These bands are in the ranges expected for pseudote-
trahedral NiII complexes [29] and can be assigned to the
transitions 3T1(F) Ǟ 3A2 (ν2) and 3T1(F) Ǟ 3T1(P) (ν3),
respectively. The spin allowed d-d transition of lowest
3.03
ligand. This demonstrates that the ligands in the complexes
are not equivalent. This situation suggests that these com-
plexes have the same structure in solution as they do in the
solid state, i.e. an octahedral environment around the metal
centre with the ligands arranged in such a way that the me-
ridional isomer is formed Ϫ as found by X-ray diffraction
for the complex [Co(4-CF3pymS)3].
Mass Spectra
3
3
energy, T1(F) Ǟ T2 (ν1), was not observed. However, the
position of this band was calculated and gave a value of
4030 to 4320 cmϪ1, which is consistent with the range ex-
pected for tetrahedral nickel(II) complexes. The magnetic
moments of these complexes, measured at room tempera-
ture, are between 3.00 and 3.43 BM and these are characte-
ristic of Ni2ϩ complexes with a tetrahedral geometry.
The electronic spectra of the mixed nickel(II) complexes
are shown in Table 8 and are consistent with systems having
an octahedral symmetry [29]. The solid state electronic
spectra of these complexes show three bands in the ranges
9940Ϫ10780, 15430Ϫ16340 and 19900Ϫ24875 cmϪ1. These
bands are consistent with octahedral Ni2ϩ complexes and
The cobalt and nickel complexes were also characterized by
mass spectrometry using the positive ion FAB technique
(m/z) in 3-nitrobenzyl alcohol (NBA) as matrix. The FAB
spectra of the cobalt(III) compounds show the molecular
ion with the appropriate isotope distribution, e.g. at m/z 638
for [Co(4-Me,6-CF3pymS)3], along with peaks due to the
fragments produced by the loss of one (m/z 445) and two
thionate ligands (m/z 252). For the [CoL2] complexes the
FAB spectra contain peaks due to the molecular ions and,
in some cases, peaks corresponding to the loss of one li-
gand molecule.
In the majority of the mass spectra of the mixed comple-
xes [Co(RpymS)2bipy] and [Co(RpymS)2phen], the molecu-
lar ion peak was not observed. However, peaks due to lower
mass species were observed and these correspond to frag-
ments formed by the loss of different groups. For example,
it is worth highlighting the peak arising from the loss of
one of the thiolate ligands and the peak corresponding to
[CoL].
3
3
can be assigned to the following transitions: A2g Ǟ T2g
3
3
3
3
(ν1), A2g Ǟ T1g(F) (ν2) and A2g Ǟ T1g(P) (ν3), respec-
tively. The magnetic moments (2.93 to 3.17 MB) are also
indicative of octahedral nickel(II) complexes. All of the data
suggest that these complexes are monomeric and the coor-
dination number six is achieved through the chelate N,S
thionate ligands, with the bipyridine or phenanthroline li-
gands also acting in a chelate fashion. Analogous octahe-
dral structures to those proposed here have also been found
by X-ray diffraction on the complexes [Ni(pyS)2bipy] [30]
and [Ni(pymS)2bipy] [31].
In some cases the spectra of the complexes [Ni(RpymS)2]
contain the expected molecular ion peak [Mϩ] along with
other lower mass peaks due to fragments resulting from the
loss of different groups. Of these peaks it is worth highligh-
ting the one due to the loss of one ligand molecule from
the molecular ion.
The spectra of the mixed complexes [Ni(RpymS)2bipy]
and [Ni(RpymS)2phen] contain a molecular ion peak along
with peaks corresponding to the loss of one [Ni(RpymS)L]
and two [NiL] of the thionate ligands.
NMR Spectra
The diamagnetic nature of the complexes [Co(RpymS)3] al-
lowed nuclear magnetic resonance spectra to be acquired
1
1
(both H and 13C). The H NMR spectra of the complexes
do not contain a signal for the NH proton of the free li-
gand, which shows that the ligands are deprotonated in the
complexes. The 1H and 13C spectra of these complexes show
three signals for each proton and carbon atom, one for each
3 Experimental Section
Acetonitrile, 1,1,1-trifluoro-2,4-pentanedione, thiourea, benzoyl-
acetone, trans-benzylideneacetophenone, 1,1,1-trifluoroacetone,
768
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Z. Anorg. Allg. Chem. 2007, 763Ϫ770

Cobalt(II), Cobalt(III), and Nickel(II) Complexes with Pyrimidine-2-thionato Ligands
benzaldehyde, sodium, 4-trifluoromethylpyrimidine-2-thione, 1,10-
phenanthroline, 2,2Ј-bipyridine, ethanol and methanol were
commercial products and were used as supplied. Cobalt and nickel
(Aldrich) were used as 2 ϫ 2 cm plates.
trifluoro-4-phenyl-3-buten-2-one (1 g, 5 mmol) was added. The
mixture was heated under reflux for a further 24 h. The solvent was
removed and the resulting solid was added to water (50 mL). The
solution was acidified with AcOH and the resulting orange solid
was filtered off. Anal.: C, 51.40; N, 11.02; H, 2.81; S, 12.39 %. Calc.
for C11F3H7N2S: C, 51.50; N, 10.93; H, 2.75; S, 12.51 %.
IR (KBr/cmϪ1): 3450Ϫ3500 (νN-H), 1650 (νCϭN). 1H NMR (300 MHz,
DMSO-d6): δ ϭ 13.0 (s, 1H, NH); 7.8 (s, 1H, H5); 7.6 (m, Ph) ppm. 13C
NMR (300 MHz, DMSO-d6): 169.30 (s, C2); 167.31 (q, C4); 110.42 (s, C5);
163.85 (s, C6); 118.54 (q, CF3); 122.98Ϫ135.32 (phenyl ring) ppm. MS
(m/z): 257.2 (Mϩ); 511 (M2ϩ).
Preparation of ligands
[4,6-CF3MepymSH]. This compound was obtained by reacting
thiourea (2.428 g, 32 mmol) and 1,1,1-trifluoro-2,4-pentanedione
(5 g, 32 mmol) in ethanol. Concentrated hydrochloric acid (1 mL)
was added in order to catalyse the reaction. The mixture was heated
under reflux for 2 h and the resulting yellow solid was filtered off.
Anal.: C: 36.39; N: 14.26; H: 2.60, S: 16.08 %. Calc. for
C6F3H5N2S: C 37.11; N 14.43; H 2.60; S 16.51 %.
Preparation of complexes
The complexes were obtained using an electrochemical method
[33]. The cell was a 100 ml tall-form beaker fitted with a rubber
bung through which the electrochemical leads entered. An acetoni-
trile solution of the ligand containing about 20 mg of tetraethyl-
ammonium perchlorate as a current carrier was electrolysed using
a platinum wire as the cathode and the cobalt plate as the sacrificial
anode. Direct current was obtained from a purpose-built d.c. power
supply. Applied voltages of 5Ϫ15 volts allowed sufficient current
flow for smooth dissolution of the metal. The current was kept at
10 mA for the time previously calculated. Hydrogen was evolved at
the cathode. The cell can be summarized as:
IR (KBr/cmϪ1): 1615 (νCϭN), 3100Ϫ3400 (νCϭN, νC-H). 1H NMR (CDCl3,
ppm): δ ϭ 14.40 (s, 1H, NH), H5, 7.19 (s, 1H, H5); Me, 2.39 (s, 3H, CH3);
Ϫ
13C NMR (300 MHz, DMSO-d6): δ ϭ 181.00 and 172.13 (s, C2); 155.86
and 153.72 [q, C4; 2J(13C-19F) ϭ 35 Hz]; 104.89 (s, C5); 163.61 (s, C6); 119.27
and 119.67 [q, CF3; 1J(13C-19F) ϭ 275 Hz]; 23.45 and 18.46 (s, CH3) ppm.
Mass spectrum (FAB): MS (m/z): 195 (Mϩ), 124 (Mϩ Ϫ CF3).
[4,6-PhMepymSH]. This ligand was obtained using a similar me-
thod to the previous compound. The precursors were benzoylace-
tone (15 g, 92.5 mmol) and thiourea (11.01 g, 144 mmol). Concen-
trated hydrochloric acid (30 mL) was added to the reaction mixture.
The product was a yellow dusty solid. Anal.: C, 66.94; N, 15.24,
H, 5.35, S, 16.01 %. Calc. for C11H10N2S: C, 65.34; N, 13.86; H,
4.95, N: 15.84 %.
M(ϩ) / CH3CN ϩ RpymSH/Pt(Ϫ)
.
IR (KBr/cmϪ1): 3000Ϫ3100 (νN-H); 1650 (νCϭN). 1H NMR (DMSO-d6,
ppm): 2.37 (s, 3 H, CH3); Ph, 7.4Ϫ8 (m); 7.3 (s, 1H, H5), 13.7 (s, 1H, NH).
MS (m/z): 203 (Mϩ), 403 (M2ϩ), 187 (Mϩ Ϫ Me).
After electrolysis, the solutions were filtered and dusty solids or
brown solutions were obtained. The solids were washed with aceto-
nitrile and diethyl ether and dried at room temperature. The solu-
tions were allowed to evaporate at room temperature. Dark green
crystals suitable for X-ray diffraction studies were obtained for
[Co(4-CF3pymS)3] by recrystallization from a dichloromethane/
ethanol mixture.
[4,6-Ph2pymSH]. The synthesis of this ligand was performed using
a different route [32]. Sodium (8.83 g, 3.84 mmol) was added to
dry ethanol (300 ml). Thiourea (7.31 g, 96 mmol) was added to the
reaction mixture and, after stirring for 15 min, trans-benzylidene-
acetophenone (20 g, 96 mmol) was added. The mixture was heated
under reflux under an inert atmosphere for 24 h. The solvent was
removed under vacuum and the resulting solid was treated with
water and filtered. The solution was adjusted to pH ϭ 6 with acetic
acid to give a yellow solid. The solid was purified by column chro-
matography. Anal.: C, 72.30, N, 10.47; H, 4.47; S, 12.73 %. Calc.
for C16H12N2S; C, 72.72; N, 10.44; H, 4.11; S, 11.94 %.
Physical measurements
The C, H, N and S contents of the compounds were determined
on Carlo Erba EA 1108 and LECO CHNS-932 microanalysers. IR
spectra were recorded as KBr mulls on a Bruker IFS-66V spectro-
1
photometer. H and 13C NMR spectra were recorded on a Bruker
IR (KBr/cmϪ1): 3400Ϫ3500 (νN-H), 1600 (νCϭN). 1H NMR (DMSO-d6,
ppm): 13.5 (broad singlet, 1 H, NH); 8.4 (s, 1H, H5), Ph, 6.90Ϫ7.20 (m). MS
(m/z): 265 (Mϩ), 527 (M2ϩ).
AMX 300 spectrometer using CDCl3 or DMSO-d6 as solvents. UV-
Vis spectra were recorded in the solid state on a Hitachi-4-3200
spectrophotometer Determination of magnetic susceptibility was
carried out on a Manics DSMS magnetometer at room tempera-
ture. FAB mass spectra were recorded on a Kratos-MS-50 using
m-NBA as matrix.
[4,6-CF3PhpymSH]. This compound was prepared using a similar
synthetic route, but in this case the precursor 1,1,1-trifluoro-4-phe-
nyl-3-buten-2-one was not a commercial product. NaOH (9.93 g)
was dissolved in water and the mixture was cooled to 0 °C. Benzal-
dehyde (5.22 g, 49 mmol) and 1,1,1-trifluoroacetone (5.21 g,
49 mmol) were added to the reaction mixture. The mixture was
allowed to warm up to room temperature and stirred for 6 h. The
mixture was then heated to 65 °C for 12 h and allowed to cool
down to room temperature. The organic compounds were removed
by extraction with CH2Cl2. The combined organic layers were dried
(MgSO4) and the solvent was removed under reduced pressure to
Crystal structure determination
The data collection was taken on a SIEMENS Smart CCD area-
detector diffractometer with graphite-monochromated Mo-Kα ra-
diation. Absorption corrections were carried out using SADABS
[34]. The structure was solved by direct methods and refined by a
full matrix least squares based on F2 [35]. Hydrogen atoms were
also included in idealised positions and refined with isotropic di-
splacement parameters. Atomic scattering factors and anomalous
dispersion corrections for all atoms were taken from International
Tables for X-ray Crystallography [36]. Details of crystal data and
structural refinement are given in Table 3. ORTEP3 drawings [37],
along with the numbering schemes used, are shown in Figure 1.
1
give a colourless liquid. H NMR (CDCl3, ppm): olefinic protons:
6.8 (dd), 6.9 (dd); Ph, 7.3 (m).
The ligand [4,6-CF3PhpymSH] was obtained by reacting thiourea
(0.38 g, 4.99 mmol) and sodium (0.459 g, 19.9 mmol) in ethanol
(40 mL). The reaction mixture was heated under refluxes and 1,1,1-
Z. Anorg. Allg. Chem. 2007, 763Ϫ770
 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
769

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A. Rodrıguez, J. A. Garcıa-Vazquez, J. Romero, A. Sousa-Pedrares, A. Sousa, J. Castro
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Crystallographic data for the structure reported in this paper
have been deposited at the Cambridge Crystallographic Data Cen-
tre as supplementary publication numbers CCDC- 631154 for
Co(4-CF3pymS)3]. Copies of the data can be obtained free of
charge on application to CCDC, 12 Union Road, Cambridge
CB2 1EZ, UK [Fax: (internat.) ϩ44-1223/336-033; E-mail:
deposit@ccdc.cam.ac.uk].
[16] R. Castro, M. L. Duran, J. A. Garcıa-Vazquez, J. Romero, A.
Sousa, E. E. Castellano, J. Zukerman-Schpector, J. Chem. Soc.
Dalton Trans. 1992, 2559.
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[17] J. A. Garcıa-Vazquez, J. Romero, A. Sousa-Pedrares, M. S.
Louro, A. Sousa, J. Zubieta, J. Chem. Soc., Dalton Trans.
2000, 559; J. A. Castro, J. Romero, J. A. Garcıa-Vazquez, M.
L. Duran, A. Sousa, E. E. Castellano, J. Zukerman-Schpector,
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Polyhedron 1992, 11, 235; P. Perez-Lourido, J. Romero, J. A.
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Garcıa-Vazquez, A. Sousa, J. Zubieta, K. Maresca, Polyhedron
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Acknowledgements. We thank the Ministerio de Educacion y
1998, 17, 4457.
Cultura of Spain and the Xunta de Galicia for financial support.
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1990, 176, 57.
[19] E. Block, H. Kang, G. Ofori-Okai, J. Zubieta, Inorg. Chim.
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www.zaac.wiley-vch.de
 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2007, 763Ϫ770