Zinc thiolate complexes of (N,N,S)-tridentate ligands for the modeling of thiolate alkylating enzymes

Article abstract of DOI:10.1002/ejic.200400927

Zinc thiolate complexes of three tridentate (N,N,S) ligands were prepared as models for the structure and function of thiolate alkylating zinc enzymes. N-(2-Mercaptoisobutyl)(2-pyridin-2-yl-methyl)amine (L¹) forms isobutylthiolate-bridged dinuclear complexes with ZnN₂S₃ coordination. N-(2-Mercaptoisobutyl)(2-pyridin-2-yl-ethyl)amine (L²) yields isobutylthiolate-bridged dinuclear complexes in which the pyridine donor is not coordinated to zinc, resulting in a ZnNS₃ coordination. Only N-(2-mercaptoisobutyl)(2-pyridin-2-yl-ethyl)methylamine (L³) forms the desired mononuclear complexes with ZnN₂S₂ coordination. The latter react with the alkylating agents CH₃I and PO(OCH₃)₃ in a two-step process. In the first step the isobutylthiolate function is methylated and its position in the ligand sphere of zinc is taken by I^- or OPO(OCH₃)₂^-, respectively, and in the second step the additional thiolate ligand is methylated and replaced by a second iodide or dimethyl phosphate anion.

Full text of DOI:10.1002/ejic.200400927

FULL PAPER
Zinc Thiolate Complexes of (N,N,S)-Tridentate Ligands for the Modeling of
Thiolate Alkylating Enzymes
Mian Ji[a] and Heinrich Vahrenkamp*[a]
Keywords: Bioinorganic chemistry / S ligands / Tridentate ligands / Zinc
Zinc thiolate complexes of three tridentate (N,N,S) ligands
were prepared as models for the structure and function of
thiolate alkylating zinc enzymes. N-(2-Mercaptoisobutyl)(2-
pyridin-2-yl-methyl)amine (L1) forms isobutylthiolate-
bridged dinuclear complexes with ZnN2S3 coordination. N-
(2-Mercaptoisobutyl)(2-pyridin-2-yl-ethyl)amine (L2) yields
isobutylthiolate-bridged dinuclear complexes in which the
pyridine donor is not coordinated to zinc, resulting in a
ZnNS3 coordination. Only N-(2-mercaptoisobutyl)(2-pyridin-
2-yl-ethyl)methylamine (L3) forms the desired mononuclear
complexes with ZnN2S2 coordination. The latter react with
the alkylating agents CH3I and PO(OCH3)3 in a two-step pro-
cess. In the first step the isobutylthiolate function is methyl-
ated and its position in the ligand sphere of zinc is taken by
I– or OPO(OCH3)2–, respectively, and in the second step the
additional thiolate ligand is methylated and replaced by a
second iodide or dimethyl phosphate anion.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
At this point the major challenges concern a better struc-
tural modeling of the enzymes, which may also be a way to
Introduction
In recent years a number of thiolate alkylating enzymes achieve higher reactivities of the zinc thiolate model com-
have been identified that contain zinc in their active cen- plexes. This requires modeling the protein environment of
ters,[1] the most prominent of which is cobalamine-indepen- zinc by tridentate or tripodal ligands with N2S and NS2
dent methionine synthase.[2] An unusual feature of these en- donor sets, of which N is part of a nitrogen heterocycle
zymes is that they contain zinc in a sulfur-rich ligand envi- representing histidine’s imidazole and S is a thiolate sulfur
ronment, which can typically be represented as NS2ZnX or representing cysteine’s thiolate. We are not aware of a model
N2SZnX, where N and S stand for the side-chains of histi- study employing such an NS2 ligand, and so far just one
dine and cysteine and X is the coordination position of the type of such N2S ligands seems to have been used for thiol-
substrate. It is believed that the thiol substrates, for example ate alkylation in zinc complexes.[8,9]
homocysteine, are attached to zinc as thioalates prior to
We have reported various tridentate N2S ligands[12–15] as
[16]
alkylation, for example to methionine. An open mechanistic well as pyrazolylborate-derived NS2 and N2S tripods.[17]
question is whether the alkylation, typically a methylation While we have previously focused on modeling hydrolytic
by methyl tetrahydrofolate, takes place at the zinc-bound or enzymes or alcohol dehydrogenase with their zinc com-
at the free thiolate.
plexes, we are at present using their zinc thiolate complexes
We[3–5] and others[6–11] have attempted to reproduce this for studies of thiolate alkylation. This paper reports our
biological process with zinc thiolate complexes of various results with the tridentate N2S systems L1–L3. The goal of
polydentate ligands, using methyl iodide, dimethyl sulfate, our study was to find out whether mononuclear tetrahedral
or trimethyl phosphate as methylating agents. In most cases L·Zn–SR complexes of L1–L3 are accessible and how they
the coligands were bidentate chelators or tripodal donors behave toward alkylating reagents.
offering only N coordination. In those cases where mechan-
istic studies were performed it was found that the thiolate
is alkylated in the zinc-bound state. Thus, a reasonable
approximation to a functional modeling of the enzymes has
been achieved, albeit with rather low reaction rates and not
in a catalytic fashion.
[a] Institut für Anorganische und Analytische Chemie der Uni-
Results and Discussion
versität Freiburg,
Albertstr. 21, 79104 Freiburg, Germany
All three ligands in their free form are aliphatic thiols
Fax: +49-761-203-6001
E-mail: vahrenka@uni-freiburg.de
and by design are good chelators. They are disubstituted at
1398
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
DOI: 10.1002/ejic.200400927
Eur. J. Inorg. Chem. 2005, 1398–1405

Zinc Thiolate Complexes of (N,N,S)-Tridentate Ligands
FULL PAPER
the α-carbon of the thiolate function with the purpose of as bridging ligands as observed before.[14] The perfectly
introducing some steric strain in order to reduce their ten- planar central Zn2S2 unit of the complex is close to being a
dency to bridge. Their synthesis consists in the ring opening square. The coordination of the zinc ions is roughly trigonal
of 2,2-dimethylthiirane by the corresponding pyridine-sub- bipyramidal (85% TBP according to the dihedral angle
stituted aliphatic amine. The two methyl substituents and method of Holmes[18]). This is not so evident from the S1–
the CH2 group of their mercaptoethylamine functions make Zn–N1 angle of 159°, but clearly so from the fact that the
it easy to identify the complexes of L1–L3 by 1H NMR axial bonds Zn–S1 and Zn–N1 are considerably longer than
spectroscopy. The zinc thiolate complexes of L1–L3 could their equatorial counterparts Zn–S1Ј, Zn–S2, and Zn–N2.
be expected to have a ZnN2S2 coordination, which in al- Complex 1 therefore closely resembles the L1·Zn-acetate
most all cases − in coordination compounds as well as in complex.[14]
zinc-containing proteins − was found to imply mononuclear
species with a tetrahedral coordination of zinc.
One reason for the inaccessibility of tetrahedral zinc
complexes with ligand L1 seems to be the fact that, upon
complexation with L1, two five-membered chelate rings are
formed. These enforce two small bond angles and therefore
encourage trigonal bipyramidal or octahedral coordination
despite the high sulfur content in the ligand sphere of the
metal. The investigations with ligand L1 were therefore
abandoned in favor of those with L2 and L3.
N-(2-Mercaptoisobutyl)(2-pyridin-2-ylmethyl)amine (L1)
Ligand L1 and some of its zinc complexes have been de-
scribed previously by us.[14] We observed that the isobutyl-
thiolate function of L1 has a high bridging tendency and
that the zinc ions in the resulting oligonuclear complexes
have coordination numbers of 5 or 6. Yet, except for the
thiolate sulfur only hard donor atoms (N and O) are pres-
ent in these complexes and the N2S2 donor composition has
not been tested.
This was done now. The thiophenolate complex 1 was
generated in a one-step synthesis from deprotonated L1,
zinc nitrate, and potassium thiophenolate. The NMR spec-
troscopic data of 1 are inconclusive in terms of composition
and structure in solution, but in the crystalline state 1 was
found to be dimeric with a ZnN2S3 coordination.
N-(2-Mercaptoisobutyl)(2-pyridin-2-ylethyl)amine (L2)
This ligand has not been described before. We now found
that it is easily accessible from 2,2-dimethylthiirane and 2-
1
(2-aminoethyl)pyridine as a colorless liquid with typical H
NMR resonances for its aliphatic constituents.
While we found it difficult to obtain zinc alkanethiolate
complexes of L2, aromatic thiolates could easily be incorpo-
rated. Again, they resulted from a one-pot synthesis using
deprotonated L2, Zn(NO3)2, and the corresponding thiol-
ate. Complexes 2a–d were obtained in reasonable yields as
colorless, crystalline materials, except for yellow 2c.
Figure 1 shows the centrosymmetrical dinuclear molecu-
lar units of 1 in which the isobutylthiolate groups function
The spectroscopic data of all four complexes 2 are similar
enough to justify the statement that they all have a structure
like the one that was determined for 2a (see Figure 2).
Again, the complexes crystallize as centrosymmetrical di-
mers with bridging isobutylthiolate functions.
The unusual feature of this structure is the noncoordina-
tion of the pyridine donor of L2. Thus, while the expected
coordination number 4 is achieved for zinc, this is not due
to the lengthening of the ligand arm between the two nitro-
gen donors but due to the fact that thiolate bridging is pre-
ferred over pyridine coordination. Therefore, with three thi-
olate ligands bound to zinc, anything but a tetrahedral co-
ordination is unlikely, and the ZnNS3 coordination pattern
ensues. The coordination geometry of zinc is extremely dis-
torted tetrahedral. The two smallest bond angles (S1–Zn–
S1Ј and S1–Zn–N2) are enforced by the Zn2S2 diamond
and the chelate ring, respectively. The opening in the ligand
sphere resulting from this then allows the very large S1–
Figure 1. Structure of 1 in the solid state. Relevant bond lengths
[Å]: Zn–S1 2.514(2), Zn–S1Ј 2.370(2), Zn–S2 2.321(2), Zn–N1
2.305(4), Zn–N2 2.134(4).
Eur. J. Inorg. Chem. 2005, 1398–1405
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1399

M. Ji, H. Vahrenkamp
FULL PAPER
Figure 2. Structure of 2a in the solid state. Relevant bond lengths [Å] and angles [°]: Zn–S1 2.375(4), Zn–S1Ј 2.377(4), Zn–S2 2.254(3),
Zn–N2 2.101(5); S1–Zn–S1Ј 99.3(1), Zn–S1–ZnЈ 80.7(1), S1–Zn–N2 90.1(1), S1–Zn–S2 130.0(1).
Zn–S2 angle. Neither of the structural features of 2a is un-
precedented. A similar dimeric structure with severe bond-
angle deviations has been described by Kellogg for an NS2
chelate ligand,[19] and we have observed the noncoordina-
tion of the pyridine arm in the ZnL2 complex of L1.[17]
N-(2-Mercaptoisobutyl)(2-pyridin-2-ylethyl)methylamine
(L3)
While ligands L1 and L2 yielded zinc complexes that are
not suitable for the intended thiolate alkylation studies, li-
gand L3, which differs from L2 only by the methyl group
Figure 3. Structure of L3·Zn–Cl. Relevant bond lengths [Å] and
on the central nitrogen atom, did allow the formation of
angles [°]: Zn–Cl 2.2354(5), Zn–S 2.2532(5), Zn–N1 2.057(1), Zn–
mononuclear tetrahedral L·Zn–SR complexes. L3 was first
N2 2.108(1); N1–Zn–N2 98.96(5), S–Zn–N2 92.72(4), Cl–Zn–N2
116.38(4), S–Zn–N1 120.09(4), Cl–Zn–N1 101.66(4), Cl–Zn–S
124.55(2).
described by Goldberg et al. and used for zinc chemistry
unrelated to thiolate alkylation,[20–22] and these authors had
already noted that the larger chelate ring size in relation to
that provided by ligands like L1 favors the formation of
four-coordinate complexes.[21] We verified the ability of L3
to form tetrahedral L·Zn–X complexes with soft donors X
by preparing L3·ZnCl from zinc chloride. The molecular
structure of L3·ZnCl (Figure 3) shows that in the mononu-
clear complexes of these ligands the tetrahedral coordina-
tion is also severely distorted due to the small bond angles
between the chelate donors and, subsequently, the large
bond angle between the two soft donors Cl and S.
Figure 4. Molecular structure of L3·Zn–SC6H5 (3d). Relevant bond
lengths [Å] and angles [°]: Zn–N1 2.076(7), Zn–N2 2.149(9), Zn–
S1 2.273(3), Zn–S2 2.277(3); N1–Zn–N2 96.9(3), N1–Zn–S1
Just like L2, ligand L3 did not facilitate access to simple
113.1(2), N1–Zn–S2 102.3(2), N2–Zn–S1 90.8(2), N2–Zn–S2
zinc alkanethiolate complexes. However, the trifluoroe- 116.0(2), S1–Zn–S2 132.4(1).
1400
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 1398–1405

Zinc Thiolate Complexes of (N,N,S)-Tridentate Ligands
FULL PAPER
thanethiolate complex 3a, the benzylthiolate complexes 3b
The preference for alkylation at the isobutylthiolate func-
and 3c, as well as the arenethiolate complexes 3d–f could tion was not so large as to prevent alkylation at the ben-
be synthesized from L3·ZnBr[21] and the corresponding thi- zenethiolate function entirely. The NMR spectra of the re-
olates. Complexes 3a–f were isolated in good yields. Except action solutions showed the presence of the aromatic thioe-
for yellow 3e they form colorless crystals.
thers before the alkylation of the aliphatic thiolate functions
The structures of 3d, 3e, and 3f were determined. They was complete. In accord with this the use of a large excess
are very similar, making it sufficient to discuss that of 3d. of the alkylating agent brought the reactions to completion
As Figure 4 shows, the ZnN2S2 coordination pattern in the according to Equation (2) under the same reaction condi-
thiolates very much resembles the ZnN2SCl coordination tions as for Equation (1).
pattern in the chloride (see Figure 3): the bond angles for
the two chelate rings are far below the tetrahedral angle,
and the S–Zn–S angle is far above it. Complex 3d shares
these features with our (N2S-chelate)Zn–SR complex de-
rived from the N2S-chelate ligand MPPA.[13] The Zn–N and
Zn–S distances of the L3·Zn–SR complexes are in the nor-
mal range, comparing well with those both in (N2S-
chelate)[12–14] and in (N2S-tripod)Zn–SR complexes.[23,24]
The coordination pattern of zinc in complexes 3 is close
enough to that in the thiolate alkylating enzymes to justify
the investigation of alkylating reactions. They were per-
The aromatic thioethers (CH3SC6H5 from 3d,
formed for 3d–f using methyl iodide and for 3d using tri-
CH3SC6H4-p-NO2 from 3e, CH3SC6F5 from 3f) were iso-
methyl phosphate. It was found that both thiolate units at-
1
lated and identified from their H NMR spectra. The pro-
tached to zinc are alkylated. However, the alkanethiolate
duct complexes 6 and 7 bearing the partially blocked ligand
function which is part of ligand L3 reacts first, according
Me-L3 offer no special features; they have the conventional
to Equation (1).
ZnN2Hal2 and ZnN2O2 compositions. The assumption that
the thioether function in these complexes is not coordinated
to zinc is backed by the fact that there is not a single struc-
ture of a complex of ZnN2Hal2 coordination known which
has any other donor coordinated to zinc.
The alkylation of 3d with trimethyl phosphate was in-
cluded in this investigation to test the ability of complexes
3 to model the function of the Ada protein, a zinc enzyme
that repairs damaged DNA by transferring alkyl groups
from its phosphate units to thiolates.[1,25] Yet, as observed
before,[1,5] trimethyl phosphate is so much less reactive than
methyl iodide that rather forcing reaction conditions had to
be applied for the alkylation process. While the reactions
with CH3I proceeded smoothly in chloroform at room tem-
perature, for the PO(OMe)3 reactions the reagents had to
be heated to 80 °C in DMSO for 10–20 days before the
formation of 5d or 7 was complete, and the products could
not be isolated pure due to partial decomposition. This sup-
Equimolar amounts of 3d–f and methyl iodide react
smoothly at room temperature in nonpolar solvents. The
conversion of ligand L3 into its methylated form Me-L3 was
1
evident from the H NMR spectra (see Experimental Sec-
tion), which also indicate by the chemical shifts of the SCH3
units that in the isolated complexes 4d–f the thioether func-
tions are not coordinated to zinc, as observed before for
ports the notion that alkylations by trimethyl phosphate
and by methyl iodide occur by different mechanisms. The
facile alkylation by methyl iodide in nonpolar media, and
a related (N2S)Zn–SR system and proved by a structure
mechanistic evidence from kinetic data,[3–5] support the as-
determination.[8] While this could not be proved here by a
sumption that it occurs as an intramolecular process at the
structure determination it corresponds to the experience
zinc-bound thiolates. The forcing conditions and the polar
that, after alkylation, the sulfur donor is released from zinc
environment needed for alkylation by trimethyl phosphate,
and replaced by the anionic constituent of the alkylating
as well as mechanistic information from related alkylations
agent.[3–5] Actually, the weak donor qualities of thioethers
of Zn(SR4)2– species by trimethyl phosphate in very polar
toward zinc, and hence their easy removal from the metal,
solvents,[26] make it likely that the thiolates dissociate from
provide an important part of the driving force for thiolate
zinc before they react.
alkylation by zinc enzymes.[1,2] For complexes 3d–f, how-
ever, the preferred alkylation at the alkanethiolate function
Conclusions
corresponds to a partial blocking of ligand L3, thereby
hampering its quality as a model ligand for biomimetic
chemistry.
In our series of investigations on the modeling of thiolate
alkylating enzymes by zinc complexes the ligands L1–L3
Eur. J. Inorg. Chem. 2005, 1398–1405
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1401

M. Ji, H. Vahrenkamp
FULL PAPER
(br. s, 1 H, CH2), 3.91 (br. s, 1 H, CH2), 4.06 (br. s, 1 H, CH2),
6.76–6.91 (m, 3 H, Ar), 7.14–7.36 (m, 5 H, Ar), 7.71 (m, 1 H, Ar),
8.36 (br. s, 1 H, Ar) ppm.
provide a coordination environment for zinc which more
closely than before resembles that in the enzymes. While
the studies have shown that L1–L3 are viable tridentate N2S
donors, they have also made clear that the peculiarities of
the coordination chemistry of zinc call for a still better con-
trol of the donor arrangement and its functionality around
the metal center.
2a: A solution of Zn(NO3)2·4H2O (0.447 g, 1.71 mmol) in 40 mL
of methanol was added dropwise, with stirring, over a period of
1 h to a solution of HL2 (0.360 g, 1.71 mmol) and 1.71 mmol of
NaOCH3 in 50 mL of methanol. Then, a solution of KSC6H5
(0.254 g, 1.71 mmol) in 40 mL of methanol was added and the mix-
ture stirred for 15 h. The solvent was removed in vacuo and the
residue taken up in 30 mL of chloroform and filtered. The solvent
was then removed in vacuo again and the product crystallized from
chloroform/hexane (1:1) to give 0.312 g (48%) of 2a as colorless
The most striking example of this is the fact that despite
their high similarity all three ligands yield zinc thiolate
complexes L·Zn–SR of completely different structure. Al-
though the ZnN2S3 pattern in 1, the ZnNS3 pattern in 2,
and the ZnN2S2 pattern in 3 can subsequently be explained,
they came as a surprise; the prevention of thiolate bridging
on going from 2 to 3 simply by attaching a methyl group
on the remote side of the coordination sphere is particularly
noteworthy. Likewise, the preferred alkylation at the ali-
phatic thiolate function of ligand L3 rather than the aro-
matic thiolate functions of the “substrates” SAr is explain-
able by the simple fact that aliphatic thiolates are more nu-
cleophilic than aromatic ones. Yet it was not predictable, as
the chelate effect should have resulted in a reduced reactiv-
ity of the intact zinc-bound L3. This sheds light on the deli-
cate balance of stability and reactivity in the thiolate alkyl-
ating zinc enzymes, specifically cobalamine-independent
methionine syntheses.[1,2] In this enzyme the substrate to be
methylated is homocysteine while the protein fixes zinc by
two cysteine residues which obviously are not to be methyl-
ated. Certainly model chemistry still needs some efforts to
reproduce this.
crystals, m.p. 191 °C. IR (KBr): ν = 1594 s, 1577 s cm–1 (C=N). 1H
˜
NMR (CDCl3): δ = 1.09 (br. s, 3 H, CH3), 1.41 (br. s, 3 H, CH3),
2.51–3.06 (br. m, 6 H, CH2), 6.77–6.91 (m, 3 H, Ar), 7.11 (t, J =
7.4 Hz, 2 H, Ph), 7.20–7.29 (m, 2 H, Ar), 7.58 (m, 1 H, Ar), 8.33
(br. s, 1 H, Ar) ppm.
2b: Like 2a from Zn(NO3)2·4H2O (0.307 g, 1.17 mmol), HL2
(0.247 g, 1.17 mmol), and HSC6H4-p-CH3 (0.145 g, 1.17 mmol).
Yield 0.246 g (53%) of 2b as colorless crystals, m.p. 191 °C.
C18H24N2S2Zn (397.92): calcd. C 54.33, H 6.08, N 7.04, S 16.12;
found C 53.94, H 6.01, N 7.34, S 16.00. IR (KBr): ν = 1594 s,
˜
1567 m cm–1 (C=N). 1H NMR (CDCl3): δ = 1.12 (br. s, 3 H, CH3),
1.40 (br. s, 3 H, CH3), 2.11 (s, 3 H, CH3), 2.42–3.05 (m, 6 H, CH2),
6.67 (d, J = 7.8 Hz, 2 H, Ar), 7.07–7.17 (m, 4 H, Ar), 7.59 (m, 1
H, Ar), 8.35 (s, 1 H, Ar) ppm.
2c: Like 2a from Zn(NO3)2·4H2O (0.468 g, 1.79 mmol), HL2
(0.377 g, 1.79 mmol), and HSC6H4-p-NO2 (0.346 g, 1.79 mmol).
Yield 0.353 g (46%) of 2c as colorless crystals, m.p. 182 °C.
C17H21N3O2S2Zn (428.89): calcd. C 47.61, H 4.93, N 9.80, S 14.95;
found C 47.52, H 4.98, N 9.78, S 14.87. IR (KBr): ν = 1570 s cm–1
˜
(C=N). 1H NMR (CDCl3): δ = 1.28 (s, 3 H, CH3), 1.44 (s, 3 H,
CH3), 2.54–3.20 (m, 6 H, CH2), 7.11–7.18 (m, 2 H, Ar), 7.45 (d, J
= 8.6 Hz, 2 H, Ar), 7.56–7.73 (m, 3 H, Ar), 8.34 (br. s, 1 H, Ar)
ppm.
Experimental Section
General: For general working and measuring procedures, see ref.[27]
Organic starting materials were obtained commercially. Ligands
L1[14] and L3[20] were prepared according to the published pro-
cedures.
2d: Like 2a from Zn(NO3)2·4H2O (0.439 g, 1.68 mmol), HL2
(0.353 g, 1.68 mmol), and HSC6F5 (0.336 g, 1.68 mmol). Yield
0.358 g (45%) of 2d as colorless crystals, m.p. 206 °C.
C17H17F5N2S2Zn (473.85): calcd. C 43.09, H 3.62, N 5.91, S 13.53;
Ligand L2: 2-(2-Aminoethyl)pyridine (1.95 g, 16.0 mmol) and 2,2-
dimethylthiirane (1.77 g, 20.0 mmol) were refluxed for 30 h in
30 mL of toluene. After cooling to room temp. and filtration the
solvent was removed in vacuo and the residue distilled to give
1.08 g (32%) of L2 as a colorless liquid, b.p. 89–90 °C/10–1 mbar.
C11H18N2S (210.34): calcd. C 62.81, H 8.63, N 13.32; found C
found C 43.04, H 3.48, N 6.04, S 13.53. IR (KBr): ν = 1598 s,
˜
1
1570 s cm–1 (C=N). H NMR (CDCl3): δ = 1.29 (br. s, 3 H, CH3),
1.40 (br. s, 3 H, CH3), 2.53–3.33 (m, 6 H, CH2), 4.73 (br. s, 1 H,
NH), 7.20–7.27 (m, 2 H, Ar), 7.71 (t, J = 7.6 Hz, 1 H, Ar), 8.49
(d, J = 4.6 Hz, 1 H, Ar) ppm. 19F NMR (CDCl3): δ = –134.0 (s, 2
F), –163.2 (s, 1 F), –165.1 (s, 2 F) ppm.
62.87, H 8.52, N 13.74. IR (film): ν = 1587 s, 1568 s cm–1 (C=N).
˜
L3·ZnCl: A solution of HL3 (0.122 g, 3.04 mmol) in 15 mL of
methanol was treated dropwise with stirring first with NaOH
(0.122 g, 3.04 mmol) in 5 mL of methanol and then with ZnCl2
(0.414 g, 3.04 mmol) in 5 mL of methanol. The mixture was stirred
for 20 h, filtered, and the filtrate evaporated to dryness. Recrystalli-
zation of the residue from methanol yielded 0.374 g (38%) of
L3·ZnCl as colorless crystals, m.p. 203 °C. C12H19ClN2S2Zn
(324.20): calcd. C 44.46, H 5.91, N 8.64; found C 43.52, H 5.88, N
1H NMR (CDCl3): δ = 1.39 (s, 6 H, CH3), 1.74 (s, 1 H, SH), 2.70
(s, 2 H, CH2), 2.98–3.18 (m, 4 H, CH2), 7.13–7.22 (m, 2 H, Ar),
7.64 (m, 1 H, Ar), 8.58 (d, J = 3.8 Hz, 1 H, Ar) ppm.
1: A solution of Zn(NO3)2·6H2O (0.440 g, 1.48 mmol) in 50 mL of
methanol was added dropwise, with stirring, within 2 h to a solu-
tion of HL1 (0.291 g, 1.48 mmol) and 1.48 mmol of KOCH3 in
50 mL of methanol. Then, a solution of KSC6H5 (0.219 g,
1.48 mmol) in 50 mL of methanol was added and the mixture
stirred for 15 h. The solvent was removed in vacuo, the residue was
taken up in 40 mL of chloroform, and filtered. The solvent was
removed in vacuo again and the residue crystallized from chloro-
form/hexane (1:1) to give 0.35 g (64%) of 1 as off-white crystals,
m.p. 198 °C. C16H20N2S2Zn·CHCl3 (369.87 + 119.38): calcd. C
41.73, H 4.33, N 5.73, S 13.11; found C 43.15, H 4.58, N 7.30, S
8.28. IR (KBr): ν = 1610 s, 1569 s cm–1 (C=N). 1H NMR (CDCl3):
˜
δ = 1.42 (s, 3 H, CH3), 1.60 (s, 3 H, CH3), 2.55 (d, J = 13.0 Hz, 1
H, CH2), 2.78 (s, 3 H, NCH3), 2.87–3.74 (m, 5 H, CH2), 7.33 (d, J
= 7.8 Hz, 1 H, Ar), 7.47 (t, J = 6.5 Hz, 1 H, Ar), 7.88 (m, 1 H,
Ar), 8.81 (d, J = 5.0 Hz, 1 H, Ar) ppm.
3a: A solution of HSCH2CF3 (0.058 g, 0.50 mmol) and 1 mL of a
0.5 m solution of NaOCH3 in methanol (0.50 mmol) in 30 mL of
12.60. IR (KBr): ν = 1604 s, 1575 s cm–1 (C=N). 1H NMR
˜
(CDCl3): δ = 1.28 (br. s, 6 H, CH3), 2.18 (br. s, 1 H, CH2), 2.78 methanol was added dropwise, with stirring, to a solution of
1402 © 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.eurjic.org
Eur. J. Inorg. Chem. 2005, 1398–1405

Zinc Thiolate Complexes of (N,N,S)-Tridentate Ligands
FULL PAPER
L3·ZnBr (0.184 g, 0.50 mmol) in 60 mL of methanol. After stirring
overnight the solvent was removed in vacuo. The residue was taken
up in 30 mL of chloroform and filtered. After removal of the sol-
vent in vacuo the product was recrystallized from methanol to yield
32 mg (16%) of 3a as colorless crystals, m.p. 125 °C.
C14H21F3N2S2Zn (403.85): calcd. C 41.64, H 5.24, N 6.94, S 15.88;
13.0 Hz, 1 H, CH2), 2.81 (s, 3 H, NCH3), 2.85–3.53 (m, 5 H, CH2),
7.31 (d, J = 7.8 Hz, 1 H, Ar), 7.46 (t, J = 6.3 Hz, 1 H, Ar), 7.80
(t, J = 7.2 Hz, 1 H, Ar), 8.85 (d, J = 5.0 Hz, 1 H, Ar) ppm. 19F
NMR (CDCl3): δ = –163.3 (s, 2 F), –161.9 (s, 1 F), –133.9 (s, 2 F)
ppm.
4d: A solution of 3d (0.100 g, 0.25 mmol) in 15 mL of chloroform
was treated with methyl iodide (0.036 g, 0.25 mmol). After stirring
for 3 d the solvent was removed in vacuo, the residue washed with
diethyl ether, and dried in vacuo to give 0.078 g (57%) of 4d as a
colorless powder, m.p. 128 °C. C19H27IN2S2Zn (539.86): calcd. C
42.27, H 5.04, N 5.19, S 11.14; found C 39.26, H 5.19, N 5.56, S
found C 41.68, H 4.56, N 6.45, S 15.44. IR (KBr): ν = 1608 s,
˜
1571 s cm–1 (C=N). 1H NMR (CDCl3): δ = 1.40 (s, 3 H, CH3), 1.57
(s, 3 H, CH3), 2.47 (d, J = 13.0 Hz, 1 H, CH2), 2.77 (s, 3 H, NCH3),
2.80–3.59 (m, 7 H, CH2), 7.31 (d, J = 7.8 Hz, 1 H, Ar), 7.45 (t, J
= 6.5 Hz, 1 H, Ar), 7.86 (m, 1 H, Ar), 8.87 (d, J = 4.4 Hz, 1 H,
Ar) ppm. 19F NMR (CDCl3): δ = –67.29 (s) ppm.
12.04. IR (KBr): ν = 1609 s, 1569 m cm–1 (C=N). 1H NMR
˜
3b: HSCH2C6H5 (0.124 g, 1.00 mmol) in 50 mL of methanol was
treated with 2.00 mL (1.00 mmol) of a 0.5 m methanol solution of
NaOCH3 and then added dropwise, with stirring, to a solution of
L3·ZnBr (0.369 g, 1.00 mmol) in 80 mL of methanol. After stirring
overnight the solvent was removed in vacuo, the residue taken up
in 25 mL of chloroform, and filtered. The filtrate was evaporated
to dryness and the product washed with diethyl ether and dried
in vacuo. Recrystallization from hexane/chloroform (2:1) yielded
(CDCl3): δ = 1.26 (s, 3 H, CH3), 1.38 (s, 3 H, CH3), 2.03 (s, 3 H,
SCH3), 2.50 (d, J = 9.2 Hz, 1 H, CH2), 2.81 (s, 3 H, NCH3), 2.84–
3.48 (m, 5 H, CH2), 6.96–7.00 (m, 3 H, Ar), 7.10–7.44 (m, 4 H,
Ar), 7.83 (br. d, J = 6.2 Hz, 1 H, Ar), 8.87 (br. s, 1 H, Ar) ppm.
4e: Like 4d from 3e (0.090 g, 0.20 mmol) and methyl iodide
(0.029 g, 0.20 mmol). Yield 0.064 g (54%) of 4e as a yellow powder,
m.p. 53 °C. C19H26IN3O2S2Zn (584.86): calcd. C 39.02, H 4.48, N
7.18, S 10.97; found C 39.30, H 4.64, N 7.02, S 10.67. IR (KBr): ν
˜
0.239 g (58%) of 3b as
a colorless powder, m.p. 139 °C.
= 1611 s, 1570 m cm–1 (C=N). 1H NMR (CDCl3): δ = 1.34 (s, 3 H,
CH3), 1.44 (s, 3 H, CH3), 2.06 (s, 3 H, SCH3), 2.54 (s, 1 H, CH2),
2.65 (s, 3 H, NCH3), 2.79–3.18 (m, 5 H, CH2), 7.28 (d, J = 7.2 Hz,
1 H, Ar), 7.61 (d, J = 8.8 Hz, 2 H, Ar), 7.68–7.84 (m, 2 H, Ar),
8.18 (d, J = 9.0 Hz, 2 H, Ar), 8.66 (br. s, 1 H, Ar) ppm.
C19H26N2S2Zn (411.95): calcd. C 55.40, H 6.36, N 6.80, S 15.57;
found C 55.14, H 6.20, N 6.67, S 14.74. IR (KBr): ν = 1607 s,
˜
1568 m cm–1 (C=N). 1H NMR (CDCl3): δ = 1.34 (s, 3 H, CH3),
1.61 (s, 3 H, CH3), 2.50 (d, J = 13.0 Hz, 1 H, CH2), 2.67 (s, 3 H,
NCH3), 2.76–3.50 (m, 5 H, CH2), 3.87 (m, 2 H, CH2), 7.07–7.28
(m, 6 H, Ar), 7.42 (t, J = 4.2 Hz, 1 H, Ar), 7.76 (m, 1 H, Ar), 8.31
(d, J = 5.4 Hz, 1 H, Ar) ppm.
4f: Like 4d from 3f (0.101 g, 0.21 mmol) and methyl iodide (0.030 g,
0.21 mmol). Yield 0.077 g (58%) of 4f as a colorless powder, m.p.
58 °C. C19H22F5IN2S2Zn (629.81): calcd. C 36.23, H 3.52, N 4.45,
3c: Like 3b from HSCH2C6H4Cl (0.159 g, 1.00 mmol), 1.00 mmol
of NaOCH3, and L3·ZnBr (0.369 g, 1.00 mmol). Yield 0.331 g
(74%) of 3c as a colorless powder, m.p. 164 °C. C19H25N2S2ClZn
(446.39): calcd. C 51.12, H 5.84, N 6.28, S 14.37; found C 51.08,
S 10.18; found C 34.78, H 3.27, N 5.13, S 9.72. IR (KBr): ν =
˜
1
1610 s, 1571 m cm–1 (C=N). H NMR (CDCl3): δ = 1.36 (s, 3 H,
CH3), 1.48 (s, 3 H, CH3), 2.11 (s, 3 H, SCH3), 2.48 (s, 1 H, CH2),
2.83 (s, 3 H, NCH3), 2.95–3.66 (m, 5 H, CH2), 7.27–7.47 (m, 2 H,
Ar), 7.68–7.80 (m, 1 H, Ar), 8.67 (br. s, 1 H, Ar) ppm. 19F NMR
(CDCl3): δ = –163.1 (s, 2 F), –161.9 (s, 1 F), –132.9 (s, 2 F) ppm.
H 5.55, N 6.13, S 13.48. IR (KBr): ν = 1606 s, 1566 s cm–1 (C=N).
˜
1H NMR (CDCl3): δ = 1.35 (s, 3 H, CH3), 1.60 (s, 3 H, CH3), 2.51
(d, J = 13.0 Hz, 1 H, CH2), 2.55 (s, 3 H, NCH3), 2.77–3.48 (m, 5
H, CH2), 3.84 (m, 2 H, CH2), 7.16–7.39 (m, 6 H, Ar), 7.79 (m, 1
H, Ar), 8.38 (d, J = 5.2 Hz, 1 H, Ar) ppm.
5d: A solution of 3d (0.116 g, 0.29 mmol) and PO(OMe)3 (0.041 g,
0.29 mmol) in 15 mL of DMSO was stirred at 80 °C for two weeks.
The solvent was then removed by distillation in vacuo. The residue
was washed with diethyl ether and dried in vacuo to give 0.116 g
(74%) of 5d as a slightly yellow wax which could not be purified
further and hence was identified only by 1H NMR spectroscopy in
CDCl3: δ = 1.40 (br. s, 6 H, CH3), 1.73 (s, 3 H, SCH3), 2.55–3.39
(m, 9 H, NCH3/CH2), 3.63 (d, J = 11.0 Hz, 6 H, OCH3), 6.90–7.10
(m, 3 H, Ar), 7.32–7.52 (m, 4 H, Ar), 7.86 (t, J = 7.6 Hz, 1 H, Ar),
8.83 (br. s, 1 H, Ar) ppm. 31P NMR (CDCl3): δ = 0.91 ppm.
3d: Like 3b from HSC6H5 (0.115 g, 1.00 mmol), 1.00 mmol of Na-
OCH3, and L3·ZnBr (0.369 g, 1.00 mmol). Yield 0.224 g (56%) of
3d as colorless crystals, m.p. 122 °C. C18H24N2S2Zn (397.92): calcd.
C 54.33, H 6.08, N 7.04, S 16.12; found C 54.30, H 6.29, N 6.99,
S 15.43. IR (KBr): ν = 1608 s, 1578 s cm–1 (C=N). 1H NMR
˜
(CDCl3): δ = 1.18 (s, 3 H, CH3), 1.38 (s, 3 H, CH3), 2.49 (d, J =
13.0 Hz, 1 H, CH2), 2.66 (s, 3 H, NCH3), 2.74–3.20 (m, 5 H, CH2),
6.90–6.95 (m, 3 H, Ar), 7.31–7.44 (m, 4 H, Ar), 7.92 (m, 1 H, Ar),
8.58 (d, J = 5.2 Hz, 1 H, Ar) ppm.
Complex 6. a) From 3d: A solution of 3d (0.120 g, 0.30 mmol) and
methyl iodide (0.214 g, 1.50 mmol) in 15 mL of chloroform was
stirred for 3 d. The solvent was then removed in vacuo and the
residue extracted with two 10-mL portions of diethyl ether. The
remaining product was dried in vacuo to give 0.148 g (88%) of 6
as a colorless powder, m.p. 59 °C. C13H22I2N2SZn (557.59): calcd.
C 28.00, H 3.98, N 5.02, S 5.75; found C 27.48, H 3.97, N 5.53, S
3e: Like 3c from HSC6H4NO2 (0.103 g, 0.66 mmol), 0.66 mmol of
NaOCH3, and L3·ZnBr (0.244 g, 0.66 mmol). Yield 0.202 g (69%)
of 3e as yellow crystals, m.p. 81 °C. C18H23N3S2O2Zn (442.92):
calcd. C 48.81, H 5.23, N 9.49, S 14.48; found C 48.50, H 5.05, N
1
9.30, S 14.28. IR (KBr): ν = 1609 s, 1569 s cm–1 (C=N). H NMR
˜
(CDCl3): δ = 1.34 (s, 3 H, CH3), 1.47 (s, 3 H, CH3), 2.54 (d, J =
13.0 Hz, 1 H, CH2), 2.73 (s, 3 H, NCH3), 2.80–3.47 (m, 5 H, CH2),
7.33 (d, J = 7.8 Hz, 1 H, Ar), 7.44 (t, J = 6.5 Hz, 1 H, Ar), 7.73
(d, J = 8.8 Hz, 2 H, Ar), 7.84–7.93 (m, 3 H, Ar), 8.72 (d, J =
1.0 Hz, 1 H, Ar) ppm.
5.27. IR (KBr): ν = 1610 s, 1570 m cm–1 (C=N). 1H NMR (CDCl3):
˜
δ = 1.53 (s, 6 H, CH3), 2.18 (s, 3 H, SCH3), 2.91 (s, 3 H, NCH3),
3.18 (br. s, 2 H, CH2), 3.41–3.52 (m, 4 H, CH2), 7.41–7.50 (m, 2
H, Ar), 7.90 (m, 1 H, Ar), 8.87 (br. s, 1 H, Ar) ppm.
3f: Like 3c from HSC6F5 (0.100 g, 0.50 mmol), 0.50 mmol of Na-
OCH3, and L3·ZnBr (0.184 g, 0.50 mmol). Yield 0.145 g (59%) of
3f as colorless crystals, m.p. 110 °C. C18H19F5N2S2Zn (487.88):
calcd. C 44.31, H 3.93, N 5.74, S 13.15; found C 44.12, H 3.46, N
The diethyl ether phase was evaporated to dryness and the remain-
ing CH3SC6H5 identified by H NMR (CDCl3): δ = 2.47 (s, 3 H,
CH3), 7.12–7.28 (m, 5 H, Ph) ppm.
1
5.37, S 11.88. IR (KBr): ν = 1611 s, 1571 m cm–1 (C=N). 1H NMR
b) From 3e: As before from 3e (0.100 g, 0.23 mmol) and methyl
iodide (0.326 g, 2.30 mmol). Yield 0.113 g (88%) of 6. Identifica-
˜
(CDCl3): δ = 1.26 (s, 3 H, CH3), 1.57 (s, 3 H, CH3), 2.53 (d, J =
Eur. J. Inorg. Chem. 2005, 1398–1405
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1403

M. Ji, H. Vahrenkamp
FULL PAPER
Table 1. Crystallographic details.
1·2CHCl3
2a
L3·ZnCl
3d
3e
3f
Empirical formula
C34H42Cl6N4S4Zn2 C34H44N4S4Zn2
C12H19ClN2SZn
324.17
0.13×0.14×0.35
P21/n
4
C18H24N2S2Zn
397.88
0.06×0.08×0.15
P212121
4
C18H23N3O2S2Zn
442.88
0.05×0.14×0.20
P21/c
4
C18H19F5N2S2Zn
487.84
0.07×0.10×0.22
P21/n
4
Molecular mass
978.49
767.79
Crystal size (mm)
Space group
Z
0.05×0.10×0.10
0.06×0.08×0.4
¯
¯
P1
P1
1
1
a [Å]
b [Å]
c [Å]
α [°]
8.801(3)
11.201(4)
11.656(4)
102.573(6)
91.473(6)
109.623(5)
1050.3(6)
1.55
7.929(2)
10.279(2)
12.440(2)
94.38(3)
105.75(3)
108.60(3)
910(3)
8.203(1)
14.979(2)
11.788(2)
90
93.436(2)
90
1445.8(4)
1.49
2.01
h: –10 to 10
k: –19 to 19
l: –15 to 15
12 971
3552
2944
7.645(2)
10.716(2)
23.273(5)
90
16.582(3)
14.918(3)
8.254(2)
90
96.545(4)
90
2028.4(6)
1.45
1.43
h: –20 to 23
k: –15 to 19
l: –10 to 10
13 303
5414
2492
10.88(2)
17.73(3)
11.01(2)
90
98.97(4)
90
2096(7)
1.55
1.42
h: –14 to 14
k: –23 to 22
l: –14 to 14
18 628
5061
1628
β [°]
90
γ [°]
90
V [ų]
1906.6(6)
1.39
d(calcd.)[gcm–3
]
1.40
μ(Mo-Kα) [mm–1
hkl range
]
1.75
1.58
1.51
h: –11 to 11
k: –14 to 14
l: –15 to 15
9099
h: –10 to 10
k: –14 to 13
l: –16 to 15
8042
h: –7 to 10
k: –8 to 13
l: –30 to 9
7110
Measured reflections
Independent reflections 4801
Observed reflections
[I Ͼ 2σ(I)]
parameters
4203
2211
4233
1918
3070
221
4801
0.063
0.178
+1.2/–1.6
199
4203
0.038
0.078
+0.9/–1.0
154
3552
0.028
0.082
+0.7/–0.6
208
4233
0.062
0.222
+0.5/–0.7
235
5414
0.049
0.130
+0.5/–0.7
253
5061
0.041
0.147
+0.4/–0.6
Refined reflections
R1 (obsd.refl.)
wR2 (all refl.)
Res. electron density
[eÅ–3
]
1
tion of CH3SC6H4-p-NO2 by H NMR (CDCl3): δ = 2.47 (s, 3 H,
W. Deck and H. Brombacher for help with the structure determi-
nations and to Mr. B. Benkmil for assistance in the laboratory.
CH3), 7.19–7.25 (m, 2 H, Ar), 8.03–8.10 (m, 2 H, Ar) ppm.
c) From 3f: As before from 3f (0.050 g, 0.10 mmol) and methyl io-
dide (0.142 g, 1.00 mmol). Yield 0.047 g (84%) of 6. Identification
of CH3SC6F5 by H NMR (CDCl3): δ = 2.47 (CH3) ppm.
[1]
[2]
[3]
G. Parkin, Chem. Rev. 2004, 104, 699–767.
R. G. Matthews, Acc. Chem. Res. 2001, 34, 681–689.
U. Brand, M. Rombach, H. Vahrenkamp, Chem. Commun.
1998, 2717–2718.
U. Brand, M. Rombach, J. Seebacher, H. Vahrenkamp, Inorg.
Chem. 2001, 40, 6151–6157.
1
Complex 7: Complex 3d (0.122 g, 0.31 mmol) and trimethyl phos-
phate (0.317 g, 1.55 mmol) in 15 mL of DMSO were stirred at
80 °C for two weeks. The solvent was then removed by distillation
in vacuo. The residue was extracted with two 10-mL portions of
diethyl ether and dried in vacuo to give 0.121 g (71%) of 7 as an
[4]
[5]
[6]
[7]
J. Seebacher, M. Ji, H. Vahrenkamp, Eur. J. Inorg. Chem. 2004,
409–417.
1
impure, waxy material which was identified by H NMR (CDCl3):
C. A. Grapperhaus, T. Tuntulani, J. H. Reibenspies, M. Y. Dar-
ensbourg, Inorg. Chem. 1998, 37, 4052–4058.
B. M. Bridgewater, T. Fillebeen, R. A. Friesner, G. Parkin, J.
Chem. Soc., Dalton Trans. 2000, 4494–4496.
B. S. Hammes, C. J. Carrano, Inorg. Chem. 2001, 40, 919–927.
C. R. Warthen, B. S. Hammes, D. C. Crans, C. J. Carrano, J.
Biol. Inorg. Chem. 2001, 6, 82–90.
δ = 1.45 (s, 6 H, CH3), 2.06 (d, J = 2.6 Hz, 3 H, SCH3), 2.61 (s, 3
H, NCH3), 2.72–3.05 (m, 4 H, CH2), 3.32 (s, 2 H, CH2), 3.64 (d, J
= 11.0 Hz, 12 H, OCH3), 7.15–7.23 (m, 2 H, Ar), 7.46 (t, J =
8.0 Hz, 1 H, Ar), 7.72 (d, J = 6.0 Hz, 1 H, Ar) ppm. 31P NMR
(CDCl3): δ = 0.55 ppm.
[8]
[9]
The diethyl ether phase was evaporated to dryness and the remain-
[10]
[11]
M. Machuqueiro, T. Darbre, J. Inorg. Biochem. 2003, 94, 193–
196.
1
ing CH3SC6H5 identified by H NMR spectroscopy as above.
Structure Determinations:[28] Crystals were obtained as described
above. Diffraction data were recorded at room temp. for 3d and 3f
and at 220 K for 1, 2a, 3e, and L3·ZnCl with a Bruker Smart CCD
diffractometer. Empirical absorption corrections (SADABS) were
applied for 1, 2a, and L3·ZnCl. The structures were solved and
refined anisotropically with the SHELX program suite.[29] Hydro-
gen atoms were included with fixed distances and isotropic tem-
perature factors 1.5-times those of their attached atoms. Parameters
S. J. Chiou, J. Innocent, C. G. Riordan, K. C. Lam. L. Liable-
Sands, A. L. Rheingold, Inorg. Chem. 2000, 39, 4347–4353.
U. Brand, H. Vahrenkamp, Inorg. Chem. 1995, 34, 3285–3293.
U. Brand, H. Vahrenkamp, Chem. Ber. 1996, 129, 435–440.
U. Brand, H. Vahrenkamp, Inorg. Chim. Acta 2000, 308, 97–
102.
A. Trösch, H. Vahrenkamp, Z. Anorg. Allg. Chem. 2001, 627,
2523–2527.
M. Shu, R. Walz, B. Wu, J. Seebacher, H. Vahrenkamp, Eur. J.
Inorg. Chem. 2003, 2502–2511.
[12]
[13]
[14]
[15]
[16]
[17]
were refined against F2. The R values are defined as R1 = Σ|Fo
–
Fc|/ΣFo and wR2 = {Σ[w(Fo – Fc ) ]Σ[w(Fo2)2]} . Drawings were
produced with SCHAKAL.[30] Table 1 lists the crystallographic
data.
2
2 2
½
B. Benkmil, M. Ji, H. Vahrenkamp, Inorg. Chem. 2004, 43,
8212–8214.
[18]
[19]
R. R. Holmes, Acc. Chem. Res. 1979, 12, 257–266.
B. Kaptein, L. Wang-Griffin, G. Barf, R. M. Kellogg, J. Chem.
Soc., Chem. Commun. 1987, 1457–1459.
S. C. Chang, R. D. Sommer, A. L. Rheingold, D. P. Goldberg,
Chem. Commun. 2001, 2396–2397.
S. C. Chang, V. V. Karambelkar, R. C. Di Targiani, D. P. Gold-
berg, Inorg. Chem. 2001, 40, 194–195.
Acknowledgments
[20]
[21]
This work was supported by the Deutsche Forschungsgemeinschaft
and the Fonds der Chemischen Industrie. We are indebted to Drs.
1404
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 1398–1405

Zinc Thiolate Complexes of (N,N,S)-Tridentate Ligands
[22] S. C. Chang, V. V. Karambelkar, R. D. Sommer, A. L. Rheing- [28] CCDC-254409 (for 1), -254410 (for 2a), -254411 (for
FULL PAPER
old, D. P. Goldberg, Inorg. Chem. 2002, 41, 239–248.
[23] B. S. Hammes, C. J. Carrano, Inorg. Chem. 1999, 38, 4593–
4600.
[24] B. S. Hammes, C. J. Carrano, J. Chem. Soc., Dalton Trans.
2000, 3304–3309.
L3·ZnCl), -254412 (for 3d), -25440 254413 (for 3e), and
-254414 (for 3f) contain the supplementary crystallographic
data for this paper. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
[25] L. C. Myers, M. P. Terranova, A. E. Ferentz, G. Wanger, G. L.
Verdine, Science 1993, 261, 1164–1167.
[26] J. J. Wilker, S. Lippard, Inorg. Chem. 1997, 36, 969–978.
[27] M. Förster, R. Burth, A. K. Powell, T. Eiche, H. Vahrenkamp,
Chem. Ber. 1993, 126, 2643–2648.
[29] SHELXTL program package for the Bruker Smart CCD dif-
fractometer, version 5.1, 2002.
[30] E. Keller, SCHAKAL for Windows, University of Freiburg,
1999.
Received: November 3, 2004
Eur. J. Inorg. Chem. 2005, 1398–1405
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1405