Dinuclear complexes with bis (benzenedithiolate) ligands

Article abstract of DOI:10.1002/1521-3765(20020315)8:6<1327::AID-CHEM1327>3.0.CO;2-N

As a part of a broader study directed towards helical coordination compounds with benzenedithiolate donors, we have synthesized the bis(benzenedithiol) ligands 1,2-bis(2,3-dimercaptobenzamido)ethane (H₄-1) and 1,2-bis(2,3-dimercaptophenyl)ethan

Full text of DOI:10.1002/1521-3765(20020315)8:6<1327::AID-CHEM1327>3.0.CO;2-N

FULL PAPER
Dinuclear Complexes with Bis(benzenedithiolate) Ligands
Han Vinh Huynh,[a] Christian Schulze-Isfort,[a] Wolfram W. Seidel,[a] Thomas L¸gger,[a]
Roland Frˆhlich,[b] Olga Kataeva,[b] and F. Ekkehardt Hahn*[a]
Dedicated to Professor Kenneth N. Raymond on the occasion of his 60th birthday
Abstract: As a part of a broader study
directed towards helical coordination
compounds with benzenedithiolate do-
nors, we have synthesized the bis(ben-
zenedithiol) ligands 1,2-bis(2,3-dimer-
captobenzamido)ethane (H4-1) and 1,2-
bis(2,3-dimercaptophenyl)ethane (H4-
2). Both ligands form dinuclear com-
plexes with NiII, NiIII and, after air-
oxidation, CoIII ions under equilibrium
[NiII (2)2] (14) were characterized by
redox potential on the type of the ligand.
The substitution of 14À for 24À on nickel
(À785 mV for 11b versus À1130 mV for
14, relative to ferrocene) affects the
redox potential to a similar degree as
the substitution of nickel for cobalt
(À1160 mV for [Co2(1)2]2À/[Co2(1)2]4À,
relative to ferrocene). The redox waves
display a markedly less reversible be-
havior for complexes with the shorter
bridged ligand 24À compared to those of
14À.
2
X-ray diffraction. In all complexes, two
square-planar [Ni(S2C6H3R)2] units are
linked in a double-stranded fashion by
the carbon backbone and they assume a
coplanar arrangement in
a stairlike
manner. Cyclic voltammetric investiga-
tions show a strong dependence of the
Keywords: cobalt ¥ cyclic voltam-
metry ¥ helicates ¥ nickel ¥ S ligands
conditions. Complexes (NEt4)4[NiII (1)2]
2
(11b), (NEt4)2[NiIII2(1)2] (13), and Na4-
containing binding groups with two different donor atoms
(e.g. aminophenoles) have been described;[9] however, sur-
prisingly, no helicates with thiolate donor functions are known
so far. This phenomenon can be rationalized in terms of the
obstacles encountered during the ligand synthesis, such as the
air sensitivity of benzene-1,2-dithiols and the often discour-
aging search for suitable equilibrium conditions for the
complex synthesis.
We have launched a systematic investigation aimed at the
incorporation of benzenedithiolate binding units into ligands
to result in helicate formation. Our interest was not only
triggered by the novelty of such ligands, but also by the
remarkable electronic and magnetic properties of benzene-
1,2-dithiolate complexes in general. A triple-stranded helicate
with nitrogen or oxygen donors, for example Fe2L3 where L ˆ
bis(catecholate) ligand, usually contains two chiral metal
atoms that are coordinated in an octahedral fashion. This does
not hold for tris(benzenedithiolate) complexes in which the
benzenedithiolate binding units can be coordinated in an
octahedral or trigonal-prismatic fashion depending on the
metal oxidation state.[10] This unique behavior of benzenedi-
thiolate complexes reveals the intriguing opportunity to
develop dinuclear coordination compounds in which the
helicity might be switched on or off by electron transfer that
causes a change in the coordination geometry at the metal
center from achiral D3h to chiral Oh. Similar arguments hold
for bis(benzenedithiolate) complexes that can adopt a square-
Introduction
The ability of polydentate ligands to form helical coordination
compounds by self-assembly with metal ions is an intriguing
field of modern metal-based supramolecular chemistry. The
first triple-stranded helical complex [Fe2(RA)3] (RA ˆ rho-
dothurulic acid), was isolated and characterized as early as
1978 by Raymond et al.,[1] almost 10 years before Lehn et al.[2]
introduced the term helicate. Although [Fe2(RA)3] contained
only oxygen donors (three hydroxamate groups for each
FeIII), the early helicate chemistry was dominated by nitrogen
donor ligands.[3] Later, Raymond et al.,[4] Albrecht and
Kotila,[5] and Stack et al.[6] developed triple-stranded helicates
based on di(catechol) ligands. Today, a large number of
helicates that are based on di(catechol) ligands have been
reported[7] and even supramolecular clusters different from
helicates can be obtained with such ligands.[8] Even helicates
[a] Prof. Dr. F. E. Hahn, Dipl.-Chem. H. V. Huynh,
Dipl.-Chem. C. Schulze-Isfort, Dr. W. W. Seidel, Dr. T. L¸gger
Anorganisch-chemisches Institut
Westf‰lische Wilhelms-Universit‰t M¸nster
Wilhelm-Klemm-Strasse 8, 48149 M¸nster (Germany)
Fax : (‡49)251-8333108
E-mail: fehahn@uni-muenster.de
[b] Dr. R. Frˆhlich, O. Kataeva
Organisch-chemisches Institut
Westf‰lische Wilhelms-Universit‰t M¸nster
Corrensstrasse 40, 48149 M¸nster (Germany)
Chem. Eur. J. 2002, 8, No. 6
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1327

F. E. Hahn et al.
FULL PAPER
pyramidal or tetrahedral coordination geometry, depending
on the oxidation state of the metal atom. This has already
been demonstrated with MnIII and MnII complexes.[11]
syntheses for 6, which involve multiple lithiation of benzene-
1,2-dithiol followed by reaction with CO2 and S-alkyla-
tion,[12b, 15] suffer from the use of expensive n-butyllithium as
well as low yields. In our search for a more efficient route to 6,
we found lithium 2,3-bis(isopropylmercapto)benzene (5) to
be an excellent precursor for the synthesis of 6. Compound 5
can be prepared by ortho-lithiation of 1,2-di(isopropylmer-
capto)benzene (4)[16] with one equivalent n-butyllithium in the
presence of TMEDA.[17] Compound 4 was obtained from o-
dichlorobenzene and sodium isopropylmercaptane in DMF.
Reaction of 5 with dry CO2 followed by hydrolysis gave nearly
quantitatively the desired product 6, which can be readily
purified by recrystallization from diethyl ether/hexane. The
bridging of two molecules 6 by standard methods[12b] with 1,2-
ethylenediamine under formation of two stable amide bonds
gave 1,2-bis[2,3-di(isopropylmercapto)benzamido]ethane (7).
Cleavage of the four S alkyl bonds in 7 with sodium/
naphthalene[12b] and hydrolysis finally afforded the bis(benze-
nedithiol) H4-1 as an off-white powder.
We have recently reported the synthesis of chelate com-
plexes with tripodal tris(benzenedithiolate) and bis(benzene-
dithiolate) ligands based on 2,3-dimercaptobenzoic acid.[12] To
obtain dinuclear complexes, these ligands had to be substi-
tuted with shorter bridging units between the benzene-1,2-
dithiol units to disable chelate formation. This led to the
synthesis of the ligands H4-1 and H4-2 in which the benzene-
dithiol units are linked by a short diamide bridge or an alkyl
chain, respectively. The difference in the type of bridge causes
The poor solubility in most organic solvents of bis(benze-
nedithiol) ligands with a diamide bridge, such as H4-1, is a
limiting factor for the study of their coordination chemistry.
To overcome this limitation, we designed and synthesized
ligand H4-2, the first example of an alkyl-bridged bis(benze-
nedithiol) ligand (Scheme 2). The synthesis of such ligands is
similar to the method employed by Albrecht et al. for the
preparation of alkyl-bridged bis(catechol) ligands.[5b] The key
step in the synthesis of H4-2 is the reaction of the lithiated
species 5 with paraformaldehyde to afford the benzyl alcohol
8. Treatment of 8 with PBr3 leads to the benzyl bromide 9,
which can undergo a Wurtz-type coupling reaction to give 10.
Finally, formation of H4-2 is accomplished by reductive
cleavage of the four S isopropyl bonds with sodium/naph-
thalene as described.[12b] As expected, and in contrast to
diamide-bridged H4-1, H4-2 is highly soluble in most common
organic solvents, such as tetrahydrofuran, dichloromethane,
chloroform, and methanol.
not only steric differences, but we also hoped it would cause
electronic consequences at the donor centers.
Herein, we report on the synthesis of the ligands H4-1 and
H4-2 as well as an improved method for the preparation of 2,3-
bis(isopropylmercapto)benzoic acid (6).[12a] An initial study of
the coordination chemistry of 14À and 24À with NiII, NiIII, and
CoIII ions is presented. Nickel[13] and cobalt[14] are known to
adopt a square-planar coordination geometry in bis(benzene-
dithiolate) complexes in the ‡2 and ‡3 oxidation states,
respectively. Therefore, no hel-
ical triple-stranded complexes
M2L3 (L ˆ bis(benzenedithio-
late)) were expected. Instead it
was assumed, that the ligands
1
4À and 24À form double-strand-
ed dinuclear complexes with
NiII, NiIII, and CoIII. In addition
we wished to study the effect of
the different bridging units in
1
4À and 24À on the properties of
the resulting complexes.
Results and Discussion
Preparation of the ligands: The
key step in the synthesis of
diamide compounds of type
H4-1 is the preparation of 2,3-
bis(isopropylmercapto)benzoic
acid (6) (Scheme 1). Published
Scheme 1. Synthesis of ligand H4-1.
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Chem. Eur. J. 2002, 8, No. 6

Dinuclear Complexes with Bis(benzenedithiolate) Ligands
1327 1335
Scheme 2. Synthesis of ligand H4-2.
Preparation of the complexes: Usually, benzenedithiolato
complexes are prepared by a simple metathesis reaction of
highly reactive alkali metal benzenedithiolates and metal
halides by salt elimination. However, the topology of the
ligands 14À and 24À also allows the formation of oligonuclear
species or even complex polymers. Therefore, a fast complex
formation reaction under kinetic control is undesirable. An
alternative to the use of alkali metal benzenedithiolates
turned out to be the ligand-transfer reaction between
titanocene benzenedithiolato complexes and tetrachlorome-
talates.[12b, 18] We have recently described the synthesis of
mononuclear bis(benzenedithiolato) cobaltate(iii) complexes
by means of this reaction.[12b,c] During our efforts to optimize
the reaction pathway to dinuclear double-stranded bis(ben-
zenedithiolato) nickelate complexes we found that both the
use of alkali benzenedithiolates as well as the ligand-transfer
reaction lead to the desired complexes when elevated reaction
temperatures and long reaction times are employed.
Scheme 3. Preparation of complexes 11a, 11b, and 13.
The dark red nickel(ii) complex Na4[Ni2(2)2] (14) was
prepared from Na4-2 and NiCl2 in methanol by salt elimi-
nation, as described for 11a (Scheme 4). Upon mixing of both
Treatment of NiCl2 or NiCl2 ¥ 6H2O with H4-1 in a 1:1
stoichiometry in the presence of four equivalents of LiOMe in
methanol under reflux conditions afforded a brown solution
of Li4[Ni2(1)2] (11a). Complex (NEt4)4[Ni2(1)2] (11b) was
isolated after metathesis with NEt4Cl as a brown air-sensitive
microcrystalline salt (Scheme 3). Complex 11b can also be
prepared by a ligand-transfer reaction between the neutral
dinuclear bis(titanocene) complex [(Cp2Ti)2(1)] (12) and
(NEt4)2[NiCl4] in an acetonitrile/tetrahydrofuran solvent
mixture under reflux conditions. The reaction can be moni-
tored visually: the color change of the reaction mixture from
dark green (12) to dark brown indicated the formation of 11b.
Aerial oxidation of 11b, as indicated by a color change from
dark brown to intense green, led to the NiIII complex
(NEt4)2[Ni2(1)2] (13). Complexes 11b and 13 are only soluble
in N,N-dimethylformamide or N,N-dimethylacetamide, re-
spectively. Both compounds can be crystallized by vapor
diffusion of benzene (11b) and diethyl ether (13) in a
concentrated N,N-dimethylformamide solution.
Scheme 4. Preparation of complexes 14 and 15.
reagents, a dark red precipitate was observed which dissolved
again when the reaction mixture was heated to reflux. This
behavior again proves the necessity to ensure equilibrium
conditions during complex synthesis. Exposure of a methanol
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F. E. Hahn et al.
FULL PAPER
solution of 14 to air resulted in a color change to green, which
indicated the formation of the NiIII/NiIII complex 15. Com-
plexes with the alkyl-bridged ligand 24À are more soluble than
their analogues with 14À. For example, complex 14 is freely
soluble in methanol, N,N-dimethylformamide, and acetone,
and slightly soluble in tetrahydrofuran. Red-brown crystals of
14 were grown from a concentrated acetone solution over a
period of three weeks at room temperature. Finally, the
intensely blue cobalt complex (NEt4)2[CoIII2(1)2] (16) was
prepared from 12 and (NEt4)2[CoCl4] in an acetonitrile/THF
solution followed by aerial oxidation.
Crystal structures: Complex 11b crystallized from a DMF/
benzene solution as solvate 11b ¥ C6H6 ¥ HC(O)N(CH3)2.
Complex 13 crystallized as a diethyl ether solvate. However,
‡
the NEt4 ions as well the diethyl ether solvent molecules are
highly disordered in crystals of 13. The disorder of the solvent
molecules could not be resolved. The diffraction data were
therefore refined against a model without solvent molecules
that accepted poor R indices. The diffraction data for 13 and
the derived molecular structure can therefore only be used to
establish the identity of the molecule and the overall
geometry (see the Experimental Section, crystal structure
determination). Crystals of 14 were obtained as an acetone/
water solvate 14 ¥ 4 CH3C(O)CH3 ¥ 3H2O. Figure 1 shows the
molecular structures of the nickelate anions with the diamide-
bridged ligand 14À (11b and 13). The anion of compound 14
and the stairlike arrangement of the NiS4 planes in this anion
are depicted in Figure 2.
Figure 1. Molecular structures of the nickelate anions in complexes 11b
(top) and 13 (bottom) with the crystallographic numbering scheme.
Hydrogen atoms, solvent molecules, and cations have been omitted.
Starred atoms in the anion of 13 are related to their corresponding atom by
a crystallographic inversion center. Selected bond lengths [ä] and angles
The structure analyses of all three complexes revealed
discrete dinuclear bis(benzenedithiolato) nickelate complex
‡
‡
anions along with NEt4 ions for 11b and 13 and Na ions for
14. Each complex anion contains two square-planar
[Ni(S2C6H3R)2] units with the nickel centers coordinated by
two benzenedithiolate units in a square-planar fashion. The
structural parameters of the [Ni(S2C6H3R)2] moieties are
À
À
À
À
[8]: 11b Ni1 S1 2.167(2), Ni1 S2 2.161(2), Ni1 S5 2.170(2), Ni1 S6
À
À
À
À
2.161(2), Ni2 S3 2.162(2), Ni2 S42.171(2), Ni2 S7 2.171(2), Ni2 S8
À
À
À
À
2.167(2), S1 C1 1.768(8), S2 C2 1.743(8), S3 C12 1.767(7), S4 C13
À
À
À
À
1.766(8), S5 C17 1.742(7), S6 C18 1.753(8), S7 C28 1.765(7), S8 C29
1.749(8); S1-Ni1-S2 91.31(8), S1-Ni1-S5 90.45(8), S1-Ni1-S6 172.34(11), S2-
Ni1-S5 174.10(9), S2-Ni1-S6 88.88(8), S5-Ni1-S6 90.13(8), S3-Ni2-S4
89.86(8), S3-Ni2-S7 89.49(8), S3-Ni2-S8 171.44(10), S4-Ni2-S7 174.84(9),
S4-Ni2-S8 90.74(8), S7-Ni2-S8 90.67(8), C1-S1-Ni1 105.2(3), C2-S2-Ni1
106.3(3), C12-S3-Ni2 106.8(3), C13-S4-Ni2 105.5(3), C17-S5-Ni1 105.3(3),
À
unexceptional. The average Ni S bond lengths in the nickel-
ate(ii) complexes 11b (2.166 ä) and 14 (2.175 ä) are slightly
longer than those in the oxidized nickelate(iii) complex 13
(2.152 ä) and are in good agreement with the values for the
À
C18-S6-Ni1 108.4(3), C28-S7-Ni2 106.9(2), C29-S8-Ni2 105.3(3); 13: Ni S1
recently reported complexes [Ni(S2C6H2tBu2)2]À2/À1 [19]
.
À
À
À
À
2.140(3), Ni S2 2.155(3), Ni S3 2.151(3), Ni S42.162(3), S1 C1 1.730(9),
À
À
À
S2 C2 1.742(9), S3 C9 1.736(10), S4 C10 1.756(10); S1-Ni-S3 88.52(10),
S1-Ni-S2 91.51(10), S1-Ni-S4 175.24(12), S2-Ni-S3 174.84(12), S2-Ni-S4
89.00(10), S3-Ni-S491.39(10), C1-S1-Ni 105.1(3), C2-S2-Ni 105.5(3), C9-S3-
Ni 105.3(4), C10-S4-Ni 105.4(3).
À
The amide N H group in catecholamide complexes is
normally involved in a hydrogen bond to the o-oxygen atom
of the catechol.[4, 6] A similar behavior was observed in the
À
anion of 11b in which all amide N H groups point to the o-
sulfur atom of the benzenedithiolate. However, only two
(O1 ¥¥¥ S2, O1* ¥¥¥ S2*) of these hydrogen bonds was observed
entities are arranged in a stairlike manner and with exactly
coplanar NiS4 planes. The coplanarity of the NiS4 planes in the
anion of 14 in the solid state is enforced by a crystallographic
inversion center in the center of the complex anion.
The distance between the two NiS4 units in the anions of
11b and 13 is longer than in 14 owing to the longer
ethylenediamide bridges. In addition, the rigid amide func-
tions decrease the flexibility of the ligand. However, these
features were insufficient for a distortion of the NiS4 planes
away from coplanarity. Thus, both 11b and 13 exhibit a stair-
type structure similar to 14. The distance between the two
nickel atoms in 14 amounts to 6.72 ä compared to 10.89 ä for
11b and 10.96 ä for 13.
À
in the anion of 13. In any case, the N H ¥¥¥ S hydrogen bonds
are weak and packing effects in the crystal structure might be
more important for the conformation of the ligand than the
formation of hydrogen bonds.
We were particularly interested to find out whether the
dinuclear anions in 11b, 13, and 14 adopt a double-stranded
helical molecular structure. Such a double-stranded helicate
would result if the two planar NiS4 units in each nickelate
anion were not arranged in a coplanar fashion. The structure
analyses, however, showed a stairlike arrangement of the NiS4
planes in all three complexes. This is illustrated in Figure 2 for
complex 14. It can be seen that the two [Ni(S2C6H3R)2]
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Dinuclear Complexes with Bis(benzenedithiolate) Ligands
1327 1335
Figure 3. Cyclic voltammograms of 11b (––) and 14 (- - - -) in DMF.
[Ni2(1)2]2À/[Ni2(1)2]4À and [Ni2(2)2]2À/[Ni2(2)2]4À couples in
N,N-dimethylformamide. Both species show quasi-reversible
two-electron transfer waves. The anodic peak potentials
versus [Cp2Fe]0/[Cp2Fe] were recorded at À785 mV and
‡
Figure 2. Molecular structure of the nickelate anion in complex 14 (top)
and of the stair-type conformation of the nickelate anion (bottom) with the
crystallographic numbering scheme. Hydrogen atoms, solvent molecules,
and cations have been omitted. Starred atoms are related to their
corresponding atom by a crystallographic inversion center. Selected bond
À1130 mV, respectively. The difference correlates well with
the electronic structure of the bridging unit. Ligand 24À, which
contains an electron-donating alkyl bridge, creates a more
electron-rich environment than 14À, which has an electron-
withdrawing diamide bridge. Thus, complexes with 24À show a
more negative reduction potential.
À
À
À
lengths [ä] and angels [8]: Ni S1 2.1712(12), Ni S2 2.1825(11), Ni S3
À
À
À
À
2.1752(12), Ni S42.1727(12), S1 C1 1.766(4), S2 C2 1.756(4), S3 C8
À
1.768(4), S4 C9 1.757(4); S1-Ni-S2 90.77(4), S1-Ni-S3 90.25(4), S1-Ni-S4
The substitution of a diamide bridge for an alkyl bridge in
the nickelate complex anions leads to a potential shift of
approximately À350 mV. The anodic peak potential of the
cobalt complex [Co2(1)2]2À/[Co2(1)2]4À was found at
À1160 mV. The change of the metal center in isostructural
complexes from nickel to cobalt again leads to a potential shift
of À375 mV. Thus, the change from the diamide-linked ligand
178.03(5), S2-Ni-S3 178.96(5), S2-Ni-S4 87.92(4), S3-Ni-S4 91.06(4), C1-S1-
Ni 105.94(14), C2-S2-Ni 105.92(14), C8-S3-Ni 105.41(14), C9-S4-Ni
105.97(14).
The deep blue crystals of 16 were also investigated by X-ray
diffraction. The diffraction data obtained were insufficient for
a satisfactory refinement of the structural parameters since
the majority of the diffraction data were of very low intensity.
However, the data were sufficient to show that complex 16 has
a molecular structure similar to the nickel complexes 11, 13,
and 14. Complex 16 contains two slightly distorted square-
planar [CoIIIS4] units, which are bridged in a double-stranded
fashion. This coordination geometry is typical for CoIII
benzenedithiolates and has also been reported for the
mononuclear CoIII complex with the ligand 1,7-bis(dimercap-
tobenzamido)heptane.[12c]
Even dinuclear bis(benzenedithiolate) complexes with
square-planar coordination geometry are able to form helical
structures. For such a helicity in a dinuclear complex, it would
be required that the MS4 planes are arranged in a non-
coplanar fashion and are twisted around the metal metal
vector. While no such helicity was found for double-stranded
dinuclear nickelate anions with bis(benzenedithiolate) li-
gands, complexes 11b, 13, and 14 are still the first examples
of dinuclear bis(benzenedithiolato) complexes in which the
two tetracoordinated metals are linked in a double-stranded
fashion by a carbon backbone.
1
4À to the alkyl linked ligand 24À affects the NiII/NiIII potential
in a comparable way to the substitution of the metal center
from nickel to cobalt in complexes of 14À. These results
corroborate the proposal[20] that the SOMO in bis(enedithio-
late) complexes carries both metal and ligand character. The
NiIII/NiIV redox couple, reported by Sellmann et al.,[19] was not
observed. The ligands 14À and 24À generate a much less
electron-rich environment than the alkyl-substituted benze-
nedithiolates used by Sellmann. The oxidation to NiIV was
expected at potentials ꢀ ‡ 1.0 V (vs. NHE). However, no
reversible redox reactions were observed in this region. We
assume that ligand oxidation occurs at potentials above 0.8 V
(vs. NHE).
The fact that each species exhibits only one redox wave
leads to the assumption that no strong intramolecular
interaction of the nickel centers exist in the dinuclear
complexes. Consequently, no mixed-valence species were
observed. However, a thorough analysis of the cyclic voltam-
mograms discloses slight differences between the couple 11b/
13 with the longer diamide bridge and the couple 14/15 with
the shorter ethylene bridge. The difference of the peak
potentials, DE, is close to ideal reversibility for 11b/13
(70 mV). The nickel centers behave as independent mono-
nuclear complexes. In contrast, DE for 14/15 amounts to
162 mV, which might indicate a slight nickel nickel inter-
action in complexes 14 and 15.
Electronic properties of the complexes: Cyclic voltammetric
and UV/Vis studies were carried out to investigate how the
bridging itself and how the type of bridge in the ligands
influences the electronic properties of the metal centers.
Figure 3 depicts the cyclic voltammograms (CV) for the
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F. E. Hahn et al.
FULL PAPER
organic layers were dried over MgSO4 and filtered. Evaporation of the
solvent and vacuum distillation yielded 4 as a colorless oil (15.27 g,
67.45 mmol, 95% based on 1,2-dichlorobenzene). 1H NMR (CDCl3,
The UV/Vis spectra of the nickel(ii/iii) complexes with
ligand 14À and 24À data are depicted in Figure 4. The spectra of
the NiII complexes 11b and 14 are similar to each other and
À
À
200 MHz, 258C): d ˆ 7.33 (dd, 2H; Ar H), 7.14(dd, 2H; Ar H), 3.48 (m,
3J ˆ 6.4Hz, 2H; SCH), 1.33 (d, 3J ˆ 6.4Hz, 12H; CH 3); 13C NMR (CDCl3,
À
50.32 MHz, 258C): d ˆ 137.5, 130.6, 126.3 (Ar C), 36.8 (SCH), 22.8
(CH3) cmÀ1; MS (70 eV, EI): m/z (%): 226 (60) [M] , 184(25) [ M À
‡
‡
‡
‡
C3H6] , 142 (100) [M À 2C3H7] , 108 (10) [M À 2C3H7 À H2S] , 97 (16)
‡
‡
‡
[C5H5S] , 78 (46) [C6H6] , 41 (81) [C3H5] ; elemental analysis calcd (%) for
C12H18S2 (226.39): C 63.66, H 8.01, S 28.32; found: C 63.92, H 7.91, S 28.26.
Lithium 2,3-bis(isopropylmercapto)benzene (5): A sample of n-butyllithi-
um (8.8 mL of a 2.5m solution in hexane, 22 mmol) was added dropwise to a
solution of TMEDA (3.3 mL, 22 mmol) and 1,2-bis(isopropylmercapto)-
benzene (4) (5.0 g, 22 mmol) in hexane (200 mL) at 08C. After 30 min, the
ice bath was removed and the stirring was continued at ambient temper-
ature for 3 h to result in the formation of an off-white slurry. The lithium
salt was used directly without further purification for the synthesis of 6.
2,3-Bis(isopropylmercapto)benzoic acid (6): Dry CO2 was bubbled through
a slurry of 5 (22 mmol) in hexane at 08C for 2 h. After evaporation of the
solvent, the residue was dissolved in water and acidified with hydrochloric
acid (37%) to pH 2. The aqueous solution was extracted with diethyl ether
(3 Â 50 mL) and the combined organic layers were dried over MgSO4.
Volatiles were removed in vacuo to afford a yellow solid. The product was
recrystallized from diethyl ether/hexane to yield an off-white powder
(5.65 g, 20.90 mmol, 95% based on 4). 1H NMR (CDCl3, 200 MHz, 258C):
Figure 4. UV/Vis spectra of complexes 11b, 13, 14, and 15 in DMF.
show the typical p p* benzene ring absorptions of the ligand
at ꢀ300 nm. Both nickel(ii) complexes also show intense
bands at l ˆ 465 nm (11b) and 385 nm (14). The spectra of the
oxidized nickel complexes 13 and 15 are also very similar to
each other and show, in addition to p p* benzene ring
absorptions ꢀ300 nm, an additional very intense band at l ˆ
860 nm for 13 and 875 nm for 15, respectively. This absorption
is typical for bis(benzenedithiolate) complexes in their
oxidized form. However, its assignment is discussed contro-
versially.[19, 21] The smaller energy gap of 15 compared to that
of 13 for this transition is interestingly correlated with the
shift to a more negative redox potential from 11b/13 to 14/15.
The UV/Vis data for complex 16 are typical for square-
planar Co(benzenedithiolate) complexes. Spectra of similar
complexes have been reported.[12c, 22]
3
3
À
d ˆ 12.24(brs, 1H; CO H), 7.66 (dd, J ˆ 3.6 Hz, J ˆ 2.4Hz, 1H; Ar H),
2
7.33 7.43 (m, 2H; Ar H), 3.54(m, 2H; SCH), 1.38 (d, 3J ˆ 6.6 Hz, 6H;
À
CH3), 1.27 (d, 3J ˆ 6.6 Hz, 6H; CH3); 13C NMR (CDCl3, 50.32 MHz, 258C):
À
d ˆ 171.3 (CO2H), 146.1, 137.8, 129.9, 129.4, 128.8, 126.1 (Ar C), 40.4
(SCH), 36.1 (SCH), 22.8 (CH3), 22.4(CH 3); IR (KBr pellet): nÄ ˆ 2658, 2561
(br, O H), 1701 (s, C O) cmÀ1; MS (70 eV, EI): m/z (%): 270 (100) [M] ,
‡
À
ˆ
‡
‡
228 (9) [M À C3H6] , 209 (21) [M À H2O À C3H7] ; elemental analysis calcd
(%) for C13H18O2S2 (270.40): C 57.74, H 6.71, S 23.71; found: C 58.00, H
6.73, S 23.24.
1,2-Bis[2,3-di(isopropylmercapto)benzamido]ethane (7): The preparation
of this compound by bridging of two molecules of 6 was carried out as
previously described[12] from 6 (1.0 g, 3.70 mmol) and 1,2-ethylenediamine
(0.106 g, 1.77 mmol). The product was isolated as a white powder (887 mg,
1.57 mmol, 85% based on 1,2-ethylenediamine). 1H NMR ([D6]DMSO,
À
200 MHz, 258C): d ˆ 8.21 (brs, 2H; CONH), 7.36 (d, 4H; Ar H), 7.10 (m,
2H; Ar H), 3.60 (m, 3J ˆ 6.3 Hz, 2H; SCH), 3.38 (m, 3J ˆ 6.5 Hz, 2H;
À
SCH), 3.34(s, 4H; CH 2), 1.30 (d, 3J ˆ 6.5 Hz, 12H; CH(CH3)2), 1.11 (d, 3J ˆ
6.3 Hz, 12H; CH(CH3)2); 13C NMR ([D6]DMSO, 50.32 MHz, 258C): d ˆ
À
168.2 (CONH), 145.5, 144.6, 128.8, 127.8, 126.4, 123.2 (Ar C), 34.7
(CH(CH3)2), 22.9 (CH(CH3)2), 22.3 (CH(CH3)2), one of the CH(CH3)2
Experimental Section
signals and the CH2 signal are hidden by the solvent peaks; IR (KBr pellet):
À
À
ˆ
nÄ ˆ 3355, 3257 (s, N H), 2960, 2923, 2863 (m, SC H), 1677 (s, C O), 1550
(s, N H), 1638, 1571, 1519 (m, Ar C C), 1442 (m, CH2) cmÀ1; MS (70 eV,
À
À ˆ
Materials and methods: If not stated otherwise, all manipulations were
performed in an atmosphere of dry argon by means of standard Schlenk
techniques. Solvents were dried by standard methods and freshly distilled
prior to use. N,N,N',N'-tetramethylethylenediamine (TMEDA) was puri-
fied by vacuum distillation from Na/benzophenone. 1H and 13C NMR
spectra were recorded on a Bruker AC200 NMR spectrometer. Elemental
analyses (C,H,N,S) were performed at the Westf‰lische Wilhelms-Uni-
versit‰t M¸nster on a Vario ELIII CHNS elemental analyzer. Mass spectra
were obtained with a Varian MAT212 (EI), Micromass Quattro LC-Z
(ESI), and DANI 8521/Finnigan MATIDT800 (GC-MS) spectrometers. IR
spectra were recorded on a Bruker Vektor22 spectrometer. UV/Vis spectra
were measured on a Varian Cary50 spectrometer. Cyclic voltammetric data
were acquired on a ECO/Metrohm PGSTAT30 potentiometer with a
platinum working electrode, an Ag/AgCl double-junction electrode (3m
KCl solution) as the reference electrode, and NBu4BF4 as the supporting
electrolyte. The complex salts (NEt4)2[NiCl4][23] and (NEt4)2[CoCl4][24] were
prepared as published.
‡
‡
EI): m/z (%): 564(46) [ M] , 521 (100) [M À iPr] , 253 (21), 211 (29), 43 (3);
elemental analysis calcd (%) for C28H40N2O2S4 (564.87): C 59.54, H 7.14, N
4.96, S 22.70; found: C 59.35, H 7.00, N 4.81, S 22.73.
1,2-Bis(2,3-dimercaptobenzamido)ethane (H4-1): Compound 7 (1.094g,
1.94mmol) and naphthalene (1.242 g, 9.70 mmol) were dissolved in
tetrahydrofuran (60 mL) and pieces of sodium (450 mg, 19.57 mmol) were
added. The mixture was stirred for 12 h at ambient temperature and then
methanol (10 mL) was added dropwise. After 10 min, the solvent was
removed in vacuo, the residue was dissolved in degassed water (20 mL),
and the mixture was filtered. The aqueous filtrate was washed with diethyl
ether (3 Â 10 mL) and acidified with hydrochloric acid (37%) to afford a
white solid. The precipitate was filtered off and washed with water (2 Â
20 mL) and diethyl ether (2 Â 10 mL). Drying in vacuo yielded H4-1 as an
off-white powder (462 mg, 1.16 mmol, 60% based on 7). 1H NMR
([D7]DMF, 200 MHz, 258C): d ˆ 8.00 (brs, 2H; CONH), 6.83 (dd, 2H;
À
À
À
Ar H), 6.71 (dd, 2H; Ar H), 6.32 (t, 2H; Ar H), 5.17 (brs, 4H; SH), 2.87
1,2-Bis(isopropylmercapto)benzene (4): This compound was prepared
(m, 4H; CH2); 13C NMR ([D7]DMF, 50.32 MHz, 258C): d ˆ 170.0 (CONH),
À
135.1, 134.0, 132.0, 126.3, 125.4 (Ar C), 40.0 (CH2); IR (KBr pellet): nÄ ˆ
similarly to
a
previously reported method.[16] 1,2-Dichlorobenzene
À
À
À
ˆ
(10.72 g, 8 mL, 71.00 mmol) was added dropwise to a suspension of sodium
isopropylmercaptane (35 g, 356 mmol) in N,N-dimethylformamide
(200 mL). The mixture was stirred for three days at 1008C and was then
allowed to cool to ambient temperature. It was then poured into water
(500 mL) and extracted with diethyl ether (3 Â 50 mL). The combined
3285 (s, N H), 3057, 2945 (w, Ar H) , 2528 (m, S H), 1633 (s, C O), 1572
(s, N H), 1536 (s, Ar C C), 1442 (m, CH2) cmÀ1; MS (70 eV, EI): m/z (%):
À
À ˆ
‡
‡
396 (31) [M] , 364(3) [ M À SH] , 228 (100), 199 (45), 168 (87), 78 (9), 34
(87); elemental analysis calcd (%) for C16H16N2O2S4 (396.55): C 48.46, H
4.07, N 7.06, S 32.34; found: C 48.43, H 4.37, N 6.80, S 31.96.
1332
¹ WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002
0947-6539/02/0806-1332 $ 17.50+.50/0
Chem. Eur. J. 2002, 8, No. 6

Dinuclear Complexes with Bis(benzenedithiolate) Ligands
1327 1335
À
127.6, 126.2 (Ar C), 35.9 (CH2); IR (KBr pellet): nÄ ˆ 3048, 3036 (w,
2,3-Di(isopropylmercapto)benzyl alcohol (8): Dry paraformaldehyde
(663 mg, 22.1 mmol) was added slowly to an off-white slurry of 5 (22 mmol)
in hexane. The mixture was stirred for two days and carefully quenched
with water (30 mL) at 08C. After acidification with hydrochloric acid
(37%), the aqueous layer was separated and extracted with diethyl ether
(3 Â 30 mL). The combined organic phases were dried over MgSO4, and
after removal of the solvent and column chromatography (SiO2, Et2O/
petrol ether, 1:3), 8 was obtained as a colorless oil (2.82 g, 11 mmol, 50%
based on 4). 1H NMR (CDCl3, 200 MHz, 258C): d ˆ 7.17 7.28 (m, 3H;
À À
À
À
Ar C H), 2943, 2926, 2855 (m, C H), 2549 (m, S H), 1440, 717
‡
(C H) cmÀ1; MS (70 eV, EI): m/z (%): 310 (100) [M] , 276 (6) [M À
À
‡
H2S] , 138 (5), 69 (9), 43 (3); elemental analysis calcd (%) for C14H14S4
(310.50): C 54.15, H 4.54, S 41.30; found: C 54.35, H 4.46, S 41.37.
[(Cp2Ti)2(1)](12) : The complex was prepared by a published method[12b,c]
from H4-1 (400 mg, 1.01 mmol) and [Cp2TiCl2] (500 mg, 2.01 mmol). The
compound was isolated as a dark green powder (530 mg, 0.71 mmol, 71%).
1
À
H NMR (CDCl3, 200 MHz, 258C): d ˆ 7.51 (m, 2H; Ar H), 7.34(brs, 2H;
À
Ar H), 4.83 (s, 2H; CH2), 3.50 (m, 2H; SCH), 2.92 (s, 1H; OH), 1.37 (d,
3
3
À
À
CONH), 7.24(d, J ˆ 7.6 Hz, 2H; Ar H), 7.17 (d, J ˆ 7.6 Hz, 2H; Ar H),
5.96 (s, 20H; C5H5), 3.74(d, 3J ˆ 5.0 Hz, 4H; CH2); 13C NMR (CDCl3,
50.32 MHz, 258C): d ˆ 169.0 (CONH), 158.6, 152.5, 136.1, 131.6, 125.1,
3J ˆ 7.2 Hz, 6H; CH3), 1.22 (d, 3J ˆ 7.2 Hz, 6H; CH3); 13C NMR (CDCl3,
À
50.32 MHz, 258C): d ˆ 146.2, 144.9, 130.4, 129.9, 125.8, 124.4 (Ar C), 64.3
(CH2), 38.9 (SCH), 35.8 (SCH), 23.0 (CH3), 22.6 (CH3); IR (KBr pellet):
À
124.6 (Ar C), 113.3 (C5H5), 39.5 (CH2); IR (KBr pellet): nÄ ˆ 3107 (m,
À
À
À
nÄ ˆ 3606, 3473 (s, O H), 3048 (w, Ar H), 2965, 2927, 2867 (m, SC H), 1560
N H), 1637, 1518 (s, C O), 815 (s, C5H5), 728 (m, Ar H) cmÀ1; elemental
analysis calcd (%) for C36H32N2O2S4Ti2 (748.66): C 57.76, H 4.31, N 3.74, S
17.13; found: C 57.66, H 4.28, N 3.52, S 16.81.
À
ˆ
À
(w, Ar C C), 782 (m, Ar H) cmÀ1; MS (70 eV, EI): m/z (%): 256 (81)
À ˆ
À
‡
‡
‡
‡
[M] , 239 (47) [M À OH] , 213 (27) [M À C3H7] , 181 (52) [M À SC3H7] ,
‡
153 (100) [M À SC3H7 À CO] ; elemental analysis calcd (%) for C13H20OS2
‡
‡
Complexes X4[Ni2(1)2](11a , X ˆ Li ) and (11b, X ˆ NEt4 ): A solution of
H4-1 (580 mg, 1.46 mmol) and LiOCH3 (6 mmol, 6 mL of a 1m solution in
MeOH) in MeOH (15 mL) was added dropwise to a solution of NiCl2
(190 mg, 1.46 mmol) in MeOH (15 mL). The mixture was heated to reflux
for 2 h. After the mixture had been cooled to ambient temperature, the
solvent was removed in vacuo. The brown residue was washed with diethyl
ether (2 Â 10 mL) and dried under vacuum to give complex 11a (yield:
605 mg, 0.65 mmol, 89% based on H4-1). Complex 11a was dissolved in
N,N-dimethylformamide and NEt4Cl (950 mg) was added. Vapor diffusion
of benzene into this concentrated solution yielded crystals of (NEt4)4-
[Ni2(1)2] ¥ C6H6 ¥ DMF (11b ¥ C6H6 ¥ DMF), which were suitable for X-ray
(256.42): C 60.89, H 7.86, S 25.01; found: C 60.47, H 7.86, S 24.66.
2,3-Di(isopropylmercapto)benzyl bromide (9): PBr3 (0.66 g, 2.44 mmol,
230 mL) was added dropwise to a solution of 8 (1.242 g, 4.84 mmol) in
diethyl ether (10 mL) at 08C. The solution was stirred for 15 min at ambient
temperature and methanol (700 mL) was added. The mixture was diluted
with diethyl ether (60 mL) and water (50 mL). The organic layer was
separated, washed with aqueous NaHCO3 (5% solution), saturated
aqueous NaCl, and dried over MgSO4. After removal of the solvent, 9
was obtained as a pale yellow oil (1.3 g, 4.07 mmol, 84%). 1H NMR
À
(CDCl3, 200 MHz, 258C): d ˆ 7.15 7.28 (m, 3H; Ar H), 4.87 (s, 2H; CH2),
3.52 (m, 2H; SCH), 1.38 (d, 3J ˆ 6.4Hz, 6H; CH 3), 1.24(d, 3J ˆ 7.0 Hz, 6H;
CH3); 13C NMR (CDCl3, 50.32 MHz, 258C): d ˆ 145.7, 143.1, 131.8, 129.0,
diffraction studies. 1H NMR for solvent-free 11a ([D7]DMF, 200 MHz,
3
À
258C): d ˆ 10.09 (brs, 4H; CONH), 7.38 (d, J ˆ 7.3 Hz, 4H; Ar H), 7.07 (d,
À
126.8, 126.3 (Ar C), 38.8 (SCH), 35.8 (SCH), 33.0 (CH2), 23.1 (CH3), 22.6
3
3
À
À
J ˆ 7.3 Hz, 4H; Ar H), 6.47 (t, J ˆ 7.3 Hz, 4H; Ar H ), 3.25 (s, 8H; CH2);
À
À
(CH3); IR (KBr pellet): nÄ ˆ 3050 (w, Ar H), 2967, 2927, 2867 (m, SC H),
13C NMR for solvent-free 11a ([D7]DMF, 50.32 MHz, 258C): d ˆ 169.7
1559 (w, Ar C C), 594(m, Ar H) cmÀ1; MS (70 eV, EI): m/z (%): (42)
À ˆ
À
À
(CONH), 157.5, 151.5, 131.6, 128.5, 122.2, 118.8 (Ar C), 39.7 (CH2); IR
‡
‡
‡
[M] , 239 (7) [M À Br] , 197 (36) [M À BrÀ C3H6] , 153 (73) [M À BrÀ
(KBr pellet): nÄ ˆ 3203 (s, N H), 1623 (s, C O) cmÀ1; elemental analysis
calcd (%) for the solvent-free powder C32H24Li4N4Ni2O4S8 (930.19): C
41.32, H 2.60, N 6.02, S 27.57; found: C 41.66, H 2.54, N 5.97, S 27.80.
À
ˆ
‡
‡
2C3H7] , 91 (45) [C7H7] , 41 (100); elemental analysis calcd (%) for
C13H19BrS2 (319.31): C 48.90, H 6.00, S 20.08; found: C 48.84, H 5.93, S
19.93.
(NEt4)2[Ni2(1)2](13) : A solution of complex 12 (200 mg, 0.27 mmol) in
tetrahydrofuran (100 mL) was added to a solution of (NEt4)2[NiCl4]
(125 mg, 0.27 mmol) in acetonitrile (100 mL). Initially the reaction mixture
was green (both 12 and the nickel salt are green in solution). While
refluxing the mixture for 12 h, the color slowly changed from green to
brown (planar NiIIS4 complexes are brown and [Cp2TiCl2] is red). Aerial
oxidation of the reaction mixture resulted in a further color change to green
again. Volatile materials were removed under vacuum and the residue was
washed with tetrahydrofuran (2 Â 20 mL) in order to remove [Cp2TiCl2].
After drying in a vacuum, complex 13 was isolated as a dark green solid
1,2-Bis[2,3-di(isopropylmercapto)phenyl]ethane (10):
A solution of 9
(1.2 g, 3.8 mmol) in tetrahydrofuran (5 mL) was added to magnesium
(46 mg, 1.9 mmol). The mixture was stirred for 30 min at ambient temper-
ature and then heated to reflux until almost all of the magnesium had
dissolved (ꢀ2 h). Volatiles were removed in vacuo and the residue was
redissolved in dichloromethane (30 mL). The solution was washed with
saturated aqueous NaCl and dried over MgSO4. Removal of the solvent
and column chromatography (SiO2, Et2O/petroleum ether 1:2) gave 10 as
an off-white solid (790 mg, 1.65 mmol, 87%). 1H NMR (CDCl3, 200 MHz,
À
258C): d ˆ 7.07 7.21 (m, 3H; Ar H), 3.47 (m, 4H; SCH), 3.16 (s, 4H;
(81 mg, 0.07 mmol, 52%). Vapor diffusion of diethyl ether into
a
CH2), 1.39 (d, 3J ˆ 6.8 Hz, 12H; CH3), 1.23 (d, 3J ˆ 6.8 Hz, 12H; CH3);
13C NMR (CDCl3, 50.32 MHz, 258C): d ˆ 147.7, 144.9, 131.2, 128.6, 125.7,
concentrated N,N-dimethylformamide solution yielded crystals of a diethyl
ether solvate (see X-ray crystallography section) suitable for X-ray
diffraction studies. MS (ESI): m/z: 451 [M À 2NEt4]2À; elemental analysis
calcd (%) for solvent-free powder C48H64N6Ni2O4S8 (1162.93): C 49.58, H
5.55, N 7.23, S 22.05; found: C 49.80, H 5.41, N 7.44, S 21.70.
À
123.9, (Ar C), 38.9 (SCH), 37.0 (CH2), 35.6 (SCH), 23.0 (CH3), 22.6 (CH3);
À
À
IR (KBr pellet): nÄ ˆ 3051 (w, Ar H), 2958, 2923, 2863 (m, SC H), 1557 (m,
Ar C C), 1444 (s, CH2), 788 (m, Ar H) cmÀ1; MS (70 eV, EI): m/z (%):
À ˆ
À
‡
‡
‡
478 (100) [M] , 435 (63) [M À C3H7] , 393 (89) [M À C3H7 À C3H6] , 351
‡
‡
Na4[Ni2(2)2](14) : A solution of H4-2 (793 mg, 2.55 mmol) and NaOCH3
(11 mmol, 11 mL of a 1m solution in MeOH) in MeOH (10 mL) was added
dropwise to a solution of NiCl2 (338 mg, 2.6 mmol) in MeOH (40 mL). The
mixture was stirred overnight and was then heated to reflux for 3 h. After
cooling to ambient temperature, the mixture was filtered and the filtrate
was dried in a vacuum. The residue was dissolved in acetone (40 mL) and
filtered again. The filtrate was concentrated to 20 mL and stored at ambient
temperature. After three weeks, red-brown needles had formed which were
collected by filtration. Further concentration of the filtrate led to the
precipitation of a second crop of crystals of 14 ¥ 4 CH3C(O)CH3 ¥ 3H2O.
These crystals were dried in vacuo to yield 535 mg, 0.65 mmol, 51% of
solvent-free 14. 1H NMR of solvent-free 14 ([D7]DMF, 200 MHz, 258C):
(48) [M À C3H7 À 2C3H6] , 309 (37) [M À SC3H7 À 3C3H6] , 275 (23) [M À
‡
‡
SC3H7 À 3C3H6 À H2S] , 241 (11) [M À SC3H7 À 3C3H6 À 2H2S] , 91 (37)
[C7H7]; elemental analysis calcd (%) for C26H38S4 (478.82): C 65.22, H 8.00,
S 26.78; found: C 64.93, H 8.01, S 27.06.
1,2-Bis(2,3-dimercaptophenyl)ethane (H4-2): A solution of 10 (840 mg,
1.75 mmol) and naphthalene (1.12 g, 8.75 mmol) in tetrahydrofuran was
treated with sodium pieces (405 mg, 17.6 mmol). The mixture was stirred
for 12 h at ambient temperature. The resulting reddish brown reaction
mixture was cooled in an ice bath and carefully quenched with methanol
(2 mL). After the mixture had been stirred for 10 min, all solvents were
removed in vacuo and the residue was redissolved in water (20 mL). The
aqueous solution was washed with diethyl ether (3 Â 20 mL) and acidified
with hydrochloric acid (37%) causing the formation of a white solid which
was extracted with dichloromethane (3 Â 20 mL). The combined pale
yellow organic layers were dried over MgSO4. Removal of the solvent
yielded H4-2 as an off-white solid (530 mg, 1.70 mmol, 97%). 1H NMR
À
À
d ˆ 7.22 (dd, 4H; Ar H), 6.62-6.52 (m, 8H; Ar H), 3.16 (s, 8H; CH2);
13C NMR of solvent-free 14 ([D7]DMF, 50.32 MHz, 258C): d ˆ 155.3, 149.8,
À
144.4, 139.6, 125.0, 124.5 (Ar C), 38.0 (CH2); elemental analysis calcd (%)
for solvent-free C28H20Na4Ni2S8 (822.28): C 40.90, H 2.45, S 31.19; found: C
41.22, H 2.32, S 30.97.
3
3
À
(CDCl3, 200 MHz, 258C): d ˆ 7.29 (dd, J ˆ 4.0 Hz, J ˆ 5.3 Hz, 2H; Ar H),
À
6.99 7.01 (m, 4H; Ar H), 3.93 (s, 2H; SH), 3.78 (s, 2H; SH), 3.04(s, 4H;
Na2[Ni2(2)2](15) : This complex was synthesized by aerial oxidation of a
methanol solution of 14 (isolated yield 56%). MS (ESI): m/z: 365 [M À
CH2); 13C NMR (CDCl3, 50.32 MHz, 258C): d ˆ 141.7, 132.5, 130.3, 129.1,
Chem. Eur. J. 2002, 8, No. 6
¹ WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002
0947-6539/02/0806-1333 $ 17.50+.50/0
1333

F. E. Hahn et al.
FULL PAPER
2Na]2À; elemental analysis calcd (%) for C28H20Na2Ni2S8 (776.30): C 43.32,
H 2.60, S 33.04; found: C 43.40, H 2.55, S 33.87.
Acknowledgement
We thank the Deutsche Forschungsgemeinschaft and the Fonds der
Chemischen Industrie for financial support.
(NEt4)2[Co2(1)2](16) : Complex 16 was synthesized by the same method as
described for 13 but with (NEt4)2[CoCl4] (185 mg, 0.40 mmol) and complex
12 (300 mg, 0.40 mmol) followed by aerial oxidation. An intense blue solid
(105 mg, 0.09 mmol, 45%) was obtained. MS (ESI): m/z: 451 [M À
2NEt4]2À
;
UV/Vis (DMF): lmax (e) ˆ 660 (19700), 365 (26900), 320
(19700molÀ1 dm3cmÀ1); elemental analysis calcd (%) for C48H64Co2N6O4S8
(1163.41): C 49.55, H 5.54, N 7.22, S 22.05; found: C 49.40, H 5.45, N 7.01, S
33.87.
[1] a) C. J. Carrano, K. N. Raymond, J. Am. Chem. Soc. 1978, 100, 5371
5374; b) C. J. Carrano, S. R. Cooper, K. N. Raymond, J. Am. Chem.
Soc. 1979, 101, 599 604.
X-ray crystallography: X-ray diffraction data were collected at À758C
(11b and 13) on a Enraf-Nonius KappaCCD or at À1208C (14) on a
Bruker AXSAPEX diffractometer both equipped with a rotating anode
and with MoKa radiation (l ˆ 0.71073 ä). An empirical absorption
correction with SORTAV[26] was applied to the raw data for 11b (0.81 ꢁ
Tꢁ 0.87) and 13 (0.79 ꢁ Tꢁ 0.97). An absorption correction with the
program SADABS[26] was applied to the data for 14 (0.71 ꢁ Tꢁ 1.00). The
structure solution was achieved in all cases with SHELXS[27] and the
refinement was carried out with SHELXL[28] with anisotropic thermal
parameters for all non-hydrogen atoms. Hydrogen atoms were added to the
structure models on calculated positions and were refined as riding atoms
(11b and 13) or were unrefined (14), respectively. ORTEP[29] was used for
all drawings of molecular structures. Additional data collection and
refinement details are listed in Table 1. The quality of the crystals of 13
was poor. Complex 13 crystallizes as a diethyl ether solvate. The solvent
molecules are disordered. Because of this disorder, the number of diethyl
ether solvent molecules could not be determined. Microanalytical data also
gave different results as the crystals rapidly loose their solvent molecules.
Therefore, no attempt was made to resolve the disorder and the solvent
molecules were not included in the refinement; this left some electron
density unaccounted for and thus led to a relatively large residual electron
density and poor R indices. However, the identity of complex 13 could be
established unequivocally. Complexes 13 and 14 reside on an inversion
center in the unit cell, the asymmetric unit contains half of the molecule.
[2] J. M. Lehn, A. Rigault, J. Siegel, J. Horrowfield, B. Chevrier, D. Moras,
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Crystallographic data (excluding structure factors) for the structures
reported in this paper have been deposited with the Cambridge Crystallo-
graphic Data Centre as supplementary publications nos. CCDC-171296
(11b), CCDC-171297 (13), and CCDC-171298 (14). Copies of the data can
be obtained free of charge on application to CCDC, 12 Union Road,
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c.ac.uk).
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Table 1. Selected crystal and data collection details for 11b, 13, and 14.
15, 305 316; b) D. Sellmann, S.
F¸nfgelder, F. Knoch, M. Moll, Z.
11b ¥ C6H6 ¥ DMF
13[a]
14 ¥ 4 CH3C(O)CH3 ¥ 3H2O
Naturforsch. B 1991, 46b, 1601
1608.
[14] R. Eisenberg, Z. Dori, H. B.
Gray, J. A. Ibers, Inorg. Chem.
1968, 7, 741 748.
formula
fw[amu]
a[ä]
b[ä]
c[ä
C73H117N9Ni2O5S8
1574.66
16.893(1)
9.918(1)
24.295(1)
90.0
99.37(1)
90.0
4016.2(5)
1.302
Pc
2
0.729
14024
91643996
0.0686
0.147
0.1201
0.1717
1.018
C48H64N6Ni2O4S8
1162.95
16.740(1)
17.436(1)
9.889(1)
90.0
96.02(1)
90.0
2870.5(4)
1.346
P21/c
2
0.992
6503
2368
0.1281
0.354
0.1787
0.3861
1.058
C40H50Na4Ni2O7S8
1108.66
7.2375(8)
13.0760(15)
13.2871(15)
98.962(2)
103.842(2)
100.532(2)
1173.9(2)
[15] D. Sellmann, T. Becker, F. Knoch,
Chem. Ber. 1996, 129, 509 519.
[16] L. Testaferri, M. Tiecco, M. Tin-
goli, D. Chianelli, M. Montanuc-
ci, Synthesis 1983, 9, 751 755.
[17] L. Horner, A. J. Lawson, G. Si-
mons, Phosphorus Sulfur 1982,
12, 353 356.
[18] a) C. M. Bolinger, T. B. Rauch-
fuss, Inorg. Chem. 1982, 21,
3947 3954; b) K. Osakada, Y.
Kawaguchi, T. Yamamoto, Orga-
nometallics 1995, 14, 4542 4548;
c) T. A. Wark, D. W. Stephan,
Can. J. Chem. 1990, 68, 565 569.
[19] D. Sellmann, H. Binder, D. Haus-
singer, F. W. Heinemann, J. Sut-
ter, Inorg. Chim. Acta 2000, 300,
829 836.
a[8]
b[8]
g[8]
V[ä3]
1calcd [gcmÀ1
]
1.568
≈
space group
P1
Z
1
m[mÀ1
]
1.242
3060
unique data
observed data {I > 2s(I)}
R1 (obs. data)
wR1
R2 (all data)
wR2
0.0433
0.1092
0.0568
0.1162
0.987
277
0.692/ À 0.450
GOF
no. of variables
res. electron density[eä3]
844
0.926/ À 0.480
266
1.915/ À 0.960
[a] See the Experimental Section for an explanation of high residual electron density and poor R indices.
1334
¹ WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002
0947-6539/02/0806-1334 $ 17.50+.50/0
Chem. Eur. J. 2002, 8, No. 6

Dinuclear Complexes with Bis(benzenedithiolate) Ligands
1327 1335
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Am. Chem. Soc. 1968, 90, 4253 4259.
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[29] ORTEP-3, L. J. Farrugia, University of Glasgow (Scotland), 1999.
Received: September 24, 2001 [F3572]
Chem. Eur. J. 2002, 8, No. 6
¹ WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002
0947-6539/02/0806-1335 $ 17.50+.50/0
1335