Copper, cobalt and platinum complexes with dithiothiophene-based ligands

Article abstract of DOI:10.1002/ejic.200500133

The preparation and characterisation of new thiophenedithiolate complexes of Cu, Co and Pt with the ligands α-tpdt and tpdt (α-tpdt = 2,3-thiophenedithiolate, tpdt = 3,4-thiophenedithiolate) is reported. The Co and Pt complexes present regular square-plan

Full text of DOI:10.1002/ejic.200500133

FULL PAPER
Copper, Cobalt and Platinum Complexes with Dithiothiophene-Based Ligands
Dulce Belo,[a] Mauro J. Figueira,[a] Joana Mendonça,[a] Isabel C. Santos,[a]
Manuel Almeida,*[a] Rui T. Henriques,[b] Maria Teresa Duarte,[c] Concepció Rovira,[d] and
Jaume Veciana[d]
Keywords: S ligands / Coordination chemistry / Copper / Cobalt / Platinum
The preparation and characterisation of new thiophenedithi-
olate complexes of Cu, Co and Pt with the ligands α-tpdt and
tpdt (α-tpdt = 2,3-thiophenedithiolate, tpdt = 3,4-thiophened-
ithiolate) is reported. The Co and Pt complexes present regu-
lar square-planar coordination geometry and low oxidation
potentials when compared with complexes with simpler li-
gands, but their monoanionic state is found to be rather un-
stable. The Co(tpdt)2 complex can be isolated both in the
monoanionic and dianionic states as a stable compound but
the Co(α-tpdt)2 and the Pt complexes can be obtained only
in the dianionic state, while their monoanionic state is un-
stable. The Co and Pt complexes can, however, be easily oxi-
dised to the neutral state, giving a fine-powdered microcrys-
talline material without high electrical conductivity. With Cu
only a less frequent geometry based on a tetrametallic CuI
cluster and three ligands is observed as [Cu4(α-tpdt)3]2– and
[Cu4(tpdt)3]2–
.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
Another common coordination geometry in bisdithi-
olene complexes is the square pyramidal, 4+1, in dimerised
arrangements, [M(S2X)2]22–, favoured for M = Fe, Co and
to a smaller extent occurring also for Ni.[6,7] Other geome-
tries are known in metal bisdithiolene complexes and, for
Introduction
Transition metal dithiolene complexes, M(S2X)2, because
of a rich variety of coordination geometry and a vivid redox
behaviour, have attracted continuing interest during the last
30 years.[1] Depending on the metal, M, coordination geom-
etry and oxidation state, these complexes can be diamag-
netic or carry different magnetic moments and therefore
have been choice building blocks for the design of func-
tional molecular materials.[2] Square-planar coordination
geometries are favoured, with metals of Ni and Cu group
in the anionic form [M(S2X)2]–, and such complexes have
been widely used as counterions in charge transfer solids
with a variety of donors, often giving rise to new molecular
materials displaying unconventional electrical and magnetic
properties, including ferromagnetism,[3] metallic[4] and even
superconducting properties.[5]
example, for Co, trimerised, [Co(S2X)2]3
,
2– [8] and even poly-
meric, [Co(S2X)2]n
,
n– [9] arrangements of square planar units
also have been described.
The accessibility to different oxidation states in these
complexes is greatly dependent on the type of ligand be-
cause their contribution to the HOMO and LUMO is often
dominant. Extended π ligands favour both a lower oxi-
dation potential and larger solid state interactions between
neighbouring units in stacked structures of square-planar
complexes. Sulfur-rich ligands with additional sulfur atoms
in the periphery of the complex are expected to provide
intermolecular S···S contacts that may enhance the magni-
tude and the dimensionality of the solid state intermo-
lecular interactions.
[a] Instituto Tecnológico e Nuclear / CFMC,
Estrada nacional 10, 2686-953 Sacavém, Portugal
Fax: +351-219-941455
E-mail: malmeida@itn1.itn.pt
[b] Instituto de Telecomunicações, Pólo de Lisboa, IST,
Av Rovisco Pais, 1049-001 Lisboa, Portugal
Fax: +351-21-8417862
E-mail: rth@ist.utl.pt
[c] Centro de Quimica Estrutural, Instituto Superior Técnico,
Av Rovisco Pais, 1049-001 Lisboa, Portugal
Fax: +351-21-8417862
In this context we recently focused our efforts on explor-
ing complexes based on thiophenedithiolate ligands (α-tpdt
= 2,3-thiophenedithiolate, dtpdt = 2,3-dihydro-5,6-thio-
E-mail: Teresa.duarte@ist.utl.pt
[d] Institut de Ciència de Materials de Barcelona (CSIC),
Campus Universitari de Bellaterra,
08193 Cerdanyola, Spain
phenedithiolate and tpdt
=
3,4-thiophenedithiolate,
Scheme 1). Previously we described the properties of the
Fax: +344-93-5805729
E-mail: cun@icmab.es
first Au[10] and Ni[11] complexes with thiophenedithiolate
Eur. J. Inorg. Chem. 2005, 3337–3345
DOI: 10.1002/ejic.200500133
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3337

M. Almeida et al.
FULL PAPER
ligands, which are generally characterised by rather low oxi- ever, difficulties in crystallising the salts of these complexes
dation potentials. Many of these complexes can be obtained with such cations led us to work with larger cations such as
as a neutral species such as Au(α-tpdt)2, one of the rare tetraphenylphosphonium (TPP), which favours the crystalli-
electrically conducting compounds based on a neutral sation process. The ligands were obtained in methanol solu-
molecule, and the first one showing metallic transport prop- tion from 5,6-thieno[2,3-d]-1,3-dithiol-2-one (1) for [M(α-
erties in spite of being characterised only as a polycrystal- tpdt)2]x– salts, and from thieno[3,4-d]-1,3-dithiol-2-thione
line sample.[10] The paramagnetic NiIII complex was the key (2) in the case of [M(tpdt)2]x– complexes, by cleavage with
component of an interesting charge transfer salt displaying potassium methoxide. These ligands, without intermediate
a metamagnetic transition.[11] More recently, other neutral isolation, were immediately treated with the appropriate
Ni complexes based on more extended bisdithiolene ligands metal chloride to give the CoII, PtII and CuI complexes,
have been obtained as single crystals and were characterised which precipitated as red (5), green (3), orange (8), dark
as unimolecular metallic systems.[12]
brown (7) and golden brown (6, 9) TPP salt, by treatment
with TPPBr. These reactions were carried out in strictly an-
aerobic conditions inside a glovebox. The TPP[Co(tpdt)2]
complex (4) was obtained as a dark blue precipitate, just by
stirring an acetonitrile solution of 3 under air. After
recrystallisation, all compounds give air-stable crystals with
yields ranging from 50 to 80%. The Pt complex 8 in aceto-
nitrile solution, when exposed to air, changes colour to
green, indicating that an oxidation process takes place, in
agreement with the low oxidation potential observed in the
cyclic voltammetry data (see below). However, possibly be-
cause of decomposition and instability of the PtIII com-
plexes, it was not possible to isolate the monoanionic spe-
cies. Although with only a slightly larger oxidation poten-
2–
tial the Pt(tpdt)2 complex 5 does not undergo any oxi-
dation upon air exposure.
With the exception of the copper salts 6 and 9, the above-
mentioned synthetic procedure leads to the dianionic spe-
cies MII with M = Co and Pt in a square-planar coordina-
tion geometry. Cu complexes are always obtained with a
different stoichiometry, of four metals to three ligands. This
stoichiometry, although unexpected, is not entirely new as
it has been previously reported for a few [Cu4(S2X)3]2– com-
plexes.[13] However in most of these previous examples the
stoichiometry of the complexes obtained is controlled by
the metal–ligand proportion, the ligand excess favouring
the formation of the square-planar CuII complex. In the
present case we were not able to obtain the square-planar
Cu coordination, even with a large excess of the ligands.
The crystal structures of complexes 4–9 were solved by
single-crystal X-ray diffraction and their crystal and struc-
ture refining data are listed in Table 1 and Table 2. The Co
and Pt complexes present identical, essentially planar, ge-
ometry (Figure 1 and Figure 2), with small nonplanar devi-
ations observed only in the thiophenic sulfur atoms of com-
plex 5, which are displaced towards opposite directions giv-
ing rise to a very small chair-type distortion.
Scheme 1. Preparation of the transition metal complexes 4–9.
These results led us to prepare similar bisthiophenedithi-
olate complexes with different transition metals and to ex-
plore their possible use as building blocks for the prepara-
tion of magnetic or electrically conducting materials. In this
paper we report on the preparation and properties of new
thiophenedithiolate complexes of Cu, Co and Pt with the
ligands α-tpdt and tpdt having diverse oxidation states and
geometries.
By contrast, this usual square-planar coordination geom-
etry, found also in the previously described Au and Ni com-
plexes with these ligands,[10,11] was not observed in the Cu
complexes 6 and 9, which present a different stoichiometry
Results and Discussion
The synthesis of TPPyM(xtpdt)z followed a procedure and structure: [Cu4(xtpdt)3]2–. In these complexes the di-
(Scheme 1) similar to the one previously described for other anion is composed by four CuI atoms, each one coordinated
transition metal complexes with dithiolatethiophene li- to the other three Cu atoms. The Cu2, Cu3 and Cu4 atoms
gands, with minor modifications. The previous preparation are chelated to two sulfurs from one dithiothiophene ligand
of Au[10] and Ni[11] complexes with thiophenedithiolate li- and to another sulfur atom from a neighbouring ligand.
gands was made as tetrabutylammonium (TBA) salts. How- Although Cu1 is also coordinated to three sulfur atoms,
3338
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 3337–3345

Copper, Cobalt and Platinum Complexes with Dithiothiophene-Based Ligands
FULL PAPER
Table 1. Crystal data and structure refinement of compounds 4, 5, 7 and 8.
TPP2[Co(α-tpdt)2] (7)
TPP[Co(tpdt)2] (4)
TPP2[Pt(tpdt)2] (5)
TPP2[Pt(α-tpdt)2] (8)
Empirical formula
Formula mass
Temperature [K]
C56H44CoP2S6
1030.14
293(2)
C32H24CoPS6
690.77
C56H44P2PtS6
1166.30
120(2)
C56H44P2PtS6
1166.30
293(2)
293(2)
¯
Crystal system, space monoclinic, P21/n
triclinic, P1
monoclinic, P21/n
monoclinic, P21/n
group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
γ [°]
11.4352(18)
14.649(3)
14.5746(15)
90.0
94.209(5)
90.0
2434.9(6)
2, 1.405
0.714
9.6591(11)
10.0699(9)
16.6435(15)
93.428(7)
106.465(8)
92.886(8)
1545.9(3)
2, 1.484
11.5361(2)
14.4982(2)
14.4816(3)
90.0
93.3204(5)
90.0
2418.02(7)
2, 1.602
3.266
11.396(2)
14.6302(18)
14.632(2)
90.0
93.856(9)
90.0
2433.9(7)
2, 1.591
3.244
Volume [Å3]
Z, Dcalcd [Mg/m3]
μ [mm–1]
F(000)
1.034
708
1066
1168
1168
Crystal size [mm]
θ range [°]
Index range (h,k,l)
0.6×0.4×0.2
1.97–26.01
–0/14, 0/18, –17/+17
0.5×0.3×0.12
2.03–26.04
0/11,–12/12, –20/19
0.36×0.108×0.02
2.91–27.48
–14/14, –18/16, –18/18
25490/5440 [Rint = 0.0520]
0.5×0.3×0.2
1.97–25.98
0/14, –17/0, –18/17
4969/4728 [Rint = 0.037]
Reflections collected/ 4974/4733 [Rint = 0.0187] 6369/5992 [Rint = 0.0236]
unique
Absorption correc-
tion
Psi-scan
Psi-scan
SORTAV
Psi-scan
Tmax and Tmin
Data/parameters
Goodness-of-fit on
F2
0.9994 and 0.9262
4733/323
1.106
0.9995 and 0.8675
5992/364
1.044
0.39761 and 0.36873
5440/295
1.021
0.9991 and 0.7707
4728/323
0.938
Final R indices [I Ͼ R1 = 0.0421, wR2 =
R1 = 0.0508, wR2 = 0.0862 R1 = 0.0264, wR2 = 0.0599 R1 = 0.0456, wR2 =
2σ(I)]
0.0851
0.341/–0.276
0.0688
0.904/–0.515
Δρmax./min. [e/A3]
0.348/–0.343
0.911/–1.206
Table 2. Crystal data and structure refinement of compounds 6 and 9.
TPP2[Cu4(α-tpdt)3] (9)
TPP2[Cu4(tpdt)3] (6)
Empirical formula
Formula mass
Temperature [K]
Wavelength [Å]
Crystal system, space group
a []
b [Å]
c [Å]
α [°]
β [°]
C60H46Cu4P2S9
1371.61
293(2)
0.71073
monoclinic, P21/c
12.1360(19)
21.0210(17)
23.3280(19)
90.000(5)
100.808(9)
90.000(5)
5845.7(11)
4, 1.558
1.851
C60H46Cu4P2S9
1371.61
293(2)
0.71069
hexagonal, P61
13.5743(14)
13.5743(14)
53.931(8)
90.000(5)
90.000(5)
120.000(5)
8606.1(18)
6, 1.588
γ [°]
Volume [Å3]
Z, Dcalcd. [Mg/m3]
μ [mm–1]
1.886
F(000)
Crystal size [mm]
θ range [°]
2784
0.5×0.2×0.1
1.71–25.98
4176
1.73–25.03
Index range (h,k,l)
Reflections collected/unique
Absorption correction
Tmax and Tmin
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I Ͼ 2σ(I)]
Δρmax./min. [e/A3]
0/14, 0/25, –28/28
11986/11428 [Rint = 0.1083]
Psi-scan
0.9998 and 0.9702
full-matrix least-squares on F2
11428/78/676
0.881
–16/13, 0/16, –64/0
15903/5090 [Rint = 0.2518]
full-matrix least-squares on F2
5090/1/676
1.012
R1 = 0.0835, wR2 = 0.0833
0.488 and –0.434
R1 = 0.1023, wR2 = 0.1739
0.809 and –0.489
Eur. J. Inorg. Chem. 2005, 3337–3345
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3339

M. Almeida et al.
FULL PAPER
the sulfur atom in the neighbouring ligand, Cu–SN, that
range from 2.216 to 2.231 and 2.212 to 2.240 for complexes
6 and 9, respectively.
Figure 1. ORTEP views and atomic numbering scheme of [Co-
(tpdt)2]– with thermal ellipsoids at 40% probability level. The
atomic numbering scheme is the same in the case of [Pt(tpdt)]2–.
Figure 4. ORTEP views and atomic numbering scheme of [Cu4(α-
tpdt)3]2– with thermal ellipsoids at 40% probability level.
Figure 2. ORTEP views and atomic numbering scheme of [Co(α-
tpdt)2]2– with thermal ellipsoids at 40% probability level. The
atomic numbering scheme is the same in the case of [Pt(α-
tpdt)2]2–.
The angles between the average planes of each ligand are
close to 70° (Figure 3 and Figure 4). In all cases, within the
ligand, the bond lengths in the thiophenic ring are very
close to those found in the corresponding Ni and Au ana-
logues (Table 3 and Table 4).[10,11] The α-tpdt complexes of
Co (7) and Pt (8) present a disorder in the orientation of
the thiophenic sulfur of the ligands (Figure 2), making it
impossible to distinguish between a cis or trans conforma-
tion of the complex, as both configurations with orientation
disorder in the crystal could give the observed results. As
each one belongs to different dithiothiophene ligands (Fig-
ure 3 and Figure 4). The Cu–Cu distances range from 2.740
to 2.640 Å and 2.729 to 2.655 Å, for complexes 6 and 9,
respectively, values which are comparable to the few similar
complexes with other dithiolate ligands.[13] The Cu–S dis-
tances can be divided into two different ranges: one, Cu–
SL, involving sulfur atoms in the same ligand that range
from 2.264 to 2.320 Å in salt 6 and 2.252 to 2.336 Å in salt
9, and the other with slightly shorter bond lengths between
[11]
[10]
the Ni(α-tpdt)2
and Au(dtpdt)2
complexes previously
studied were found to crystallise in the trans configuration,
the observed disorder is most likely the result of orienta-
tional disorder of the complex in the trans configuration.
In this respect it should be mentioned that in those cases
one specific orientation of the complexes is favoured by se-
veral hydrogen bonds and strong S···S contacts involving
the thiophenic ring, and therefore preventing possible orien-
tational disorder of the complex in those structures. This is
at variance with the structure of 7 and 8 where there are no
strong thiophenic S···S contacts and the existing hydrogen
bonds do not present any specific orientation.
Two different types of crystal packing were found on the
studied salts. The first one consists of isolated anions, sur-
rounded by the TPP cations and this type of crystal packing
is shared for complexes 5, 6, 7, 8 and 9 (Figure 5 and Fig-
ure 6). Although they are not isostructural, they present the
same crystal packing pattern. The interactions between the
anions and the cations are established through several hy-
drogen bonds. The interactions found are of the C–H···S
type, involving both the thiophenic and the coordination
sulfur atoms (Table 5). The effect on the crystal structure
Figure 3. ORTEP views and atomic numbering scheme of
[Cu4(tpdt)3]2– with thermal ellipsoids at 40% probability level.
3340
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 3337–3345

Copper, Cobalt and Platinum Complexes with Dithiothiophene-Based Ligands
FULL PAPER
Table 3. Selected bond lengths [Å] for [M(L)2]x– in complexes 4, 5, 7 and 8.
[Co(α-tpdt)]2–
[Co(tpdt)]–
[Pt(tpdt)]2–
[Pt(α-tpdt)]2–
M–S1
M–S2
M–S4
M–S5
2.2139(7)
2.2215(8)
2.177(1)
2.182(1)
2.178(1)
2.167(1)
1.749(4)
1.760(4)
1.753(4)
1.746(4)
--
2.3109(6)
2.3113(6)
2.306(2)
2.314(2)
–
–
–
–
–
–
S1–C1
S2–C2
S4–C5
S5–C6
S3–C2
S3–C4
S3–C3
S30–C1
S30–C40
S6–C7
S6–C8
C1–C2
C5–C6
C1–C3
C3–C4
C2–C4
C2–C30
C5–C7
C6–C8
C30–C40
1.743(3)
1.736(3)
1.759(3)
1.754(3)
1.740(8)
1.731(7)
–
–
–
–
–
–
–
1.713(4)
1.689(10)
1.736(16)
1.690(40)
1.709(4)
1.710(4)
–
1.715(3)
1.721(3)
–
–
1.717(14)
1.72(2)
–
–
–
–
1.718(13)
1.710(30)
–
–
1.702(4)
1.708(5)
1.420(5)
1.417(5)
1.359(5)
–
1.345(5)
–
1.361(5)
1.368(5)
–
–
–
–
1.355(4)
–
1.47(2)
1.39(2)
–
1.437(3)
1.351(10)
–
–
1.362(4)
1.530(40)
1.470(60)
–
1.370(3)
–
1.55(3)
–
–
–
–
–
1.410(50)
–
–
–
1.45(3)
1.420(80)
Figure 6. View of the crystal structure of 9 along a.
Figure 5. View of the crystal structure of 7 along a. The crystal
packing for complexes 5 and 8 is very similar.
of the sulfur atom position in the thiophenic ring (tpdt or
α-tpdt) is negligible.
Cyclic voltammetry of all TPPyM(xtpdt)z was performed
in acetonitrile versus Ag/AgCl and the redox potential val-
The crystal structure of 4 is composed by layers of dithi- ues of the different processes observed are listed in Table 6.
olate anions parallel to the bc plane, with TPP cations sit- As in the case of the Au and Ni compounds previously
ting in holes in these layers. The anionic layers are due to a described, these new transition metal complexes with dithi-
network of short contacts. Anions of one type are con- olatethiophene ligands present lower oxidation potentials
nected between the terminal sulfur atoms by short than complexes with more simple bisdithiolene ligands such
S(3)···S(3)* [3.492(2) Å] contacts making regular chains as maleonitrile dithiolate (mnt) or even benzodithiolate
along b. These chains are interconnected by another dithiol- (bdt). With the exception of the copper complexes, which
ate anion, placed almost perpendicularly to the first ones, present a different stoichiometry and coordination environ-
through short S6···C1 contacts [3.436(2) Å] (Figure 7). This ment, when going from tpdt to α-tpdt ligands the redox
last contact may denote a weak interaction between this S potentials decrease, showing an increasing facility of these
atom and the carbon π system. The TPP cations are sitting complexes to be oxidised. The complexes with M = Co, Pt
over the spaces left in this anionic layer.
present at negative values a reversible process ascribed to
Eur. J. Inorg. Chem. 2005, 3337–3345
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3341

M. Almeida et al.
FULL PAPER
Table 4. Selected bond lengths [Å] for [Cu4(L)3]2– in complexes 6
and 9.
Table 5. Selected hydrogen bonds and short contacts in the crystal
structure of complexes 4–9.
tpdt
α-tpdt
4
d [Å]
Angle [°]
Cu1–Cu2
Cu1–Cu3
Cu1–Cu4
Cu2–Cu3
Cu2–Cu4
Cu3–Cu4
Cu1–S1
Cu1–S5
Cu1–S7
Cu2–S8
Cu2–S4
Cu2–S5
Cu3–S2
Cu3–S8
Cu3–S7
Cu4–S4
Cu4–S2
Cu4–S1
S1–C1
S2–C2
S3–C3
S3–C4
S3–C1
S4–C5
S5–C6
S6–C8
S6–C7
S6–C6
S7–C9
S8–C10
S9–C11
S9–C12
S9–C10
C2–C1
C5–C6
C9–C10
C1–C3
C2–C4
C3–C4
C5–C7
C6–C8
C7–C8
C9–C11
C10–C12
C11–C12
2.696(2)
2.675(2)
2.690(2)
2.740(2)
2.641(2)
2.640(2)
2.284(4)
2.286(4)
2.303(4)
2.216(4)
2.276(4)
2.314(5)
2.231(4)
2.280(4)
2.320(4)
2.220(4)
2.264(4)
2.316(4)
1.765(15)
1.757(14)
1.723(16)
1.732(15)
–
1.803(16)
1.733(17)
1.701(18)
1.710(19)
–
1.758(13)
1.755(15)
1.692(15)
1.706(14)
–
2.727(2)
2.688(2)
2.690(2)
2.670(2)
2.652(2)
2.681(3)
2.280(4)
2.290(3)
2.294(3)
2.233(4)
2.256(5)
2.308(4)
2.211(4)
2.288(4)
2.312(5)
2.235(4)
2.274(4)
2.333(4)
1.703(13)
1.768(12)
1.733(16)
–
1.706(12)
1.734(16)
1.714(15)
1.860(20)
–
1.711(12)
1.675(15)
1.788(19)
–
S3···S3[a]
3.492(2)
3.436(2)
2.815(1)
2.980(1)
–
–
137
158
S6···C1
C14–H14···S5
C33–H33···S5
5
d [Å]
Angle [°]
C24–H24···S1
C33–H33···S2
C44–H44···S3
2.895(1)
2.821(1)
2.897(1)
170
152
139
6
d [Å]
Angle [°]
C22–H24···S5
C64–H64···S6
C36–H36···S8
2.855(3)
2.919(6)
2.909(4)
141
148
137
7
d [Å]
Angle [°]
C43–H43···S1
C24–H24···S2
C12–H12···S3
C12–H12···S30
2.851(1)
2.940(1)
2.942(4)
2.798(13)
144
171
129
177
8
d [Å]
Angle [°]
C43–H43···S1
C24–H24···S2
C12–H12···S3
C12–H12···S30
2.832(2)
2.944(2)
2.941(17)
2.759(13)
145
173
129
176
9
d [Å]
Angle [°]
C22–H22···S2
C94–H94···S5
C53–H53···S6
C75–H75···S7
C86–H86···S9
2.934(5)
2.966(4)
2.833(6)
2.860(4)
2.951(10)
135
124
160
147
120
1.742(12)
1.733(14)
1.397(15)
1.412(17)
1.330(20)
–
1.567(16)
1.250(20)
1.505(15)
–
1.466(17)
1.424(19)
1.457(18)
1.354(17)
1.331(16)
–
1.319(18)
1.349(19)
–
[a] –x + 1, –y + 2, –z + 1.
–0.330 V, quasireversible for Cu4(α-tpdt)3 at about –0.392 V
(–0.506, –0.278) and an irreversible oxidation at higher po-
tentials of about 0.18 V.
As suggested by the cyclic voltammetry data, in the case
of Pt and Co complexes, the corresponding neutral
metal(iv) complexes were easily obtained by chemical oxi-
dation as fine and very insoluble precipitates. The same
1.130(30)
1.620(19)
–
1.349(17)
1.326(15)
–
1.130(12)
the M(xtpdt)22–/M(xtpdt)2 couple. These low values are in products, as judged by elemental analysis and IR, were also
agreement with the fact that the Co(tpdt)2 complex was obtained by electrochemical oxidation from acetonitrile
–
–
obtained from the dianionic species upon air oxidation and solutions containing the TPPy[M(xtpdt)2] salts. Using stan-
2–
with the previously mentioned fact that Pt(α-tpdt)2
dard electrocrystallisation galvanostatic conditions with a
changes colour upon air exposure, indicative of oxidation. current density of 1 μA/cm2 for about 7–12 days, in a two-
In spite of not so different oxidation potentials, Co(α- compartment cell with platinum electrodes, only an equally
tpdt)22– and Pt(tpdt)22– do not denote any air oxidation and fine and insoluble microcrystalline dark powder was ob-
the monoanionic species could not be isolated, probably be- tained. The elemental analysis of these products is consis-
cause of instability associated with dismutation in the neu- tent with the neutral complex. Further characterisation of
tral and dianionic species. The Co and Pt complexes also these products was hampered by the difficulty in the prepa-
show an irreversible process at more positive potentials, ration of single crystals because of the large insolubility of
possibly associated with the formation of the insoluble neu- these neutral complexes in most solvents. However, the
tral complexes, which could be obtained by chemical oxi- measurements of the electrical conductivity by the four-
dation (see below). The Cu complexes also undergo two probe method in compressed powder pellets indicated con-
redox processes, a reversible wave for Cu4(tpdt)3 at ductivity lower than 10–6 S/cm.
3342
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 3337–3345

Copper, Cobalt and Platinum Complexes with Dithiothiophene-Based Ligands
FULL PAPER
Figure 7. View of the crystal structure of 4 along a. On the right side the anionic layer in 4 is shown in detail, emphasising the short
S3···S3* and S6···C1 contacts, responsible for the two-dimensional dithiolate network.
Table 6. Cyclic voltammetry of [M(L)2]x– complexes.
Compound
E1/2(MIǞMII) [mV]
E1/2(MIIǞMIII) [mV]
E1/2(MIIIǞMIV) [mV]
Ref.
TPP[Co(tpdt)2]
TPP2[Co(α-tpdt)2]
TPP2[Pt(tpdt)2]
TPP2[Pt(α-tpdt)2]
TBA[Au(α-tpdt)2]
TBA[Au(tpdt)2]
TBA[Ni(α-tpdt)2]
TBA2[Co(mnt)2]
TBA2[Pt(mnt)2]
–618
–591
–253
–519
–1162
+497
–257/–175/–8
+416
this work
this work
this work
+69/+152/+278
+456
this work
[10]
[10]
[11]
[1a]
–900
+754[a]/+1319
+253
–562
–384[a]
–231[a] (–160)
+853 (+720)
[1a] [b], ([19] [c]
)
TPP2[Cu4(tpdt)3]
TPP2[Cu4(α-tpdt)3]
–330
–506/–278
+148/+293
+182/+430
this work
this work
[a] MIII Ǟ MIII/IV. [b] In DMF, vs. Ag/AgCl. [c] In acetonitrile vs. Ag/Ag+.
Cary 5G spectrophotometer (Varian). IR spectra were obtained
with a Perkin–Elmer 577 spectrophotometer. MALDI mass spectra
were obtained in time-of-flight negative linear mode with an appa-
Summary
New thiophenedithiolate complexes of Cu, Co and Pt
with the ligands α-tpdt and tpdt were prepared. The Cu ratus Kratus Kompact Maldi 2 K probe (KRATOS Analytical) op-
erated with pulsed extraction of the ions. Cyclic voltammetry data
were obtained by using a BAS C3 Cell Stand. The measurements
were performed at room temperature in acetonitrile solutions con-
taining nBu4PF6 as supporting electrolyte, with a scan rate of
100 mV/s, platinum wire working and counter electrodes and using
a Ag/AgCl as a reference electrode.
complexes obtained, independently of the metal to ligand
ratio, present a tetrametallic CuI cluster and three ligands:
[Cu4(α-tpdt)3]2– and [Cu4(tpdt)3]2–. The Co and Pt com-
plexes, with square-planar coordination geometry, are ob-
tained in the dianionic state. In spite of their low oxidation
potential, only for Co(tpdt)2 was it possible to isolate the
monoanionic complex and in other cases this oxidation
Tetraphenylphosphonium Salt of Cobalt(III) Bis(3,4-thiophenedithiol-
state is rather unstable. Further oxidation of these com- ate), TPPCo(tpdt)2 (4): Whilst stirring, thieno[3,4-d]-1,3-dithiol-2-
thione (1) (100 mg, 5.25×10–4 mol) was added to a solution of po-
tassium methoxide in methanol (10 mL, 2 m). The formed yellow
plexes to the neutral state gives an electrically insulating
powder material.
solution was filtered and added to
a solution (2 mL) of
CoCl2·6H2O (63 mg, 2.6×10–4 mol) in methanol, turning to a
green mixture. The inorganic precipitate was removed and the
liquor added to 1 mL of a solution of tetraphenylphosphonium
bromide (222 mg, 5.25×10–4 mol) in methanol giving a green pre-
cipitate, 3. The green solid obtained was dissolved in acetonitrile
and stirred under air. Just a few minutes later the solution turned
from green to dark blue. After an hour this solution was filtered
and evaporated, giving 4 as a blue precipitate. The stirring was
maintained, in all steps, only until no visible modifications were
observed. The best crystals of 4, suitable for X-ray measurements,
Experimental Section
General Remarks: All manipulations were carried out with ex-
clusion of air under dry nitrogen or argon unless otherwise stated.
All solvents were purified following standard procedures. Thi-
eno[3,4-d]-1,3-dithiol-2-thione (1) and 5,6-thieno[2,3-d]-1,3-dithiol-
2-one (2) were synthesised as described previously. Other chemicals
were commercially obtained and used without any further purifica-
tion. Column chromatography was carried out using silica gel
(0.063–0.2 mm) from S.D.S. UV/Vis spectra were recorded with a were obtained from crystallisation in acetonitrile/ethyl ether. Total
Eur. J. Inorg. Chem. 2005, 3337–3345
www.eurjic.org © 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 3343

M. Almeida et al.
FULL PAPER
yield: 79%, 142 mg; C56H44CoP2S6 (3) (1030.20): calcd. C 65.29, H
4.30, S 18.67; found C 64.61, H 3.85, S 17.63; C32H24PS6Co (4)
(690.81): calcd. C 55.64, H 3.50, S 27.84; found C 56.23, H 3.68, S
Cobalt(IV) Bis(3,4-thiophenedithiolate), Co(tpdt)2 (10): A solution
of iodine in acetone was added to a solution of 4 in acetone
(10 mL, 1.5×10–2 m), dropwise in stoichiometric amounts. The fine
26.95. FTIR (KBr) ν = 3060 (m) (arom. C–H), 1580 (s) (C=C str.), dark precipitate obtained was isolated by centrifugation, washed
˜
1480 (s) (C–H, ring C=C str.), 1460 (s) (=C–H, ring C=C), 1310 by Soxhlet extraction with acetone and dried in vacuo. Yield 32%,
(s), 1125 (s), 990 (s), 840 (s), 760 (s), 725 (s) (C–S), 690 (s) (C–S), 17 mg; C8H4CoS6 (351.41: calcd. C 27.34, H 1.15, S 54.74; found
630 (m) (C–S), 530 (s) cm–1. UV/Vis (CH3CN) λmax = 1915 nm; C 27.11, H 1.07, S 53.15.
m.p. 67 °C dec. MS: m/z (%) = 352 (100) [M–].
Platinum(IV) Bis(3,4-thiophenedithiolate), Pt(tpdt)2 (11): Using as
starting material 5 and following the same procedure used for 10,
the neutral species was obtained as a fine-powdered dark solid.
Yield 28%, 20 mg; C8H4PtS6 (487.57): calcd. C 19.71, H 0.83, S
39.45; found C 19.03, H 0.95, S 37.14.
Bis(tetraphenylphosphonium) Salt of Platinum(II) Bis(3,4-thiophene-
dithiolate), TPP2Pt(tpdt)2 (5): The compound was prepared using
the same method as for 4, using NaPtCl4·3H2O instead of
CoCl2·6H2O. The product was obtained as dark red plate crystals,
directly by synthesis, allowing the final solution to rest overnight.
Yield: 50%, 152 mg; C56H44P2PtS6 (1166.36): calcd. C 57.67, H
Cobalt(IV), Bis(2,3-thiophenedithiolate), Co(α-tpdt)2 (12): Using as
starting material 7 and following the same procedure used for 10,
the neutral species was obtained as a fine-powdered dark solid.
Yield 45%, 24 mg; C8H4CoS6 (351.41): calcd. C 27.34, H 1.15, S
54.74; found C 26.94, H 1.14, S 53.04.
3.80, S 16.49; found C 56.79, H 3.94, S 16.89; FTIR (KBr) ν =
˜
3520 (m), 3440 (m) (C–H arom.), 1440 (s) (P-φ), 1300 (s), 1105 (s),
720 (s) (C–S), 690 (m) (C–S), 530 (s) cm–1. UV/Vis (CH3CN): λmax
= 871, 1915 nm; m.p. gradual decomposition 300 °C. MS: m/z (%)
= 487.5 (100) [M–].
Platinum(IV), Bis(2,3-thiophenedithiolate), Pt(α-tpdt)2 (13): Using
as starting material 8 and following the same procedure used for
10, the neutral species was obtained as a fine-powdered dark solid.
Yield 37%, 27 mg, C8H4PtS6 (487.57): calcd. C 19.71, H 0.83, N
0.00, S 39.45; found C 19.94, H 1.14, N 0.00, S 35.83.
Bis(tetraphenylphosphonium) Salt of Copper(I) Tris(3,4-thiophenedi-
thiolate), TPP2Cu4(tpdt)3 (6): The compound was prepared using
the same method as for 4, using CuCl2·2H2O instead of
CoCl2·6H2O. The product was obtained as a brown precipitate. The
best crystals, suitable for X-ray measurements, were obtained by
recrystallisation in acetonitrile/ethyl ether. Yield: 62%, 55 mg;
C60H46Cu4P2S9 (1371.69): calcd. C 52.54, H 3.38, S 21.03; found
X-ray Crystallographic Study: The data collection was performed at
room temperature for all compounds on an Enraf–Nonius CAD4
diffractometer equipped with a graphite monochromatised Mo-Kα
radiation (λ = 0.71069 Å) in the ω-2θ-scan mode, except in the case
of compound 5, where data were collected at 120 K with a Nonius
KAPPA CCD using a Mo rotating anode using φ- and ω-scans.
Data collection and refinement details are presented in Table 1.
C 53.88, H 3.52, S 20.66; FTIR (KBr) ν = 1584 (m), 1482 (m),
˜
1439 (m) (C-φ), 1277 (m), 1109 (s), 997 (m), 839 (m), 755 (s), 726
(s), 689 (s) (C–S), 531 (s) cm–1. UV/Vis (CH3CN): λmax = 1912 nm;
m.p. 120 °C dec. MS: m/z (%) = 325 (100) [C8H4S5Cu], 209.7
[C4H2S3Cu], 693.5 [M–].
The structures were solved by direct methods using SIR97[14] and
refined by full-matrix least-squares methods using the program
SHELXL97[15] and the winGX software package.[16] All non-hydro-
gen atoms were refined anisotropically. Hydrogen atoms were
placed in idealised positions and allowed to refine riding on the
parent C atom. Molecular graphics were prepared using OR-
TEP 3[17] and SCHAKAL-97.[18] Crystal data and structure refine-
ment are summarised in Tables 5 and 6. Experimental details,
atomic coordinates, and bond lengths and angles have been de-
posited in the Cambridge Crystallographic Data Centre (CCDC).
CCDC-263500–263505 for compounds 4–9 contain the supplemen-
tary crystallographic data for this paper. These data can be ob-
tained free of charge from the CCDC via www.ccdc.cam.ac.uk/
data_request/cif.
Tetraphenylphosphonium Salt of Cobalt(III) Bis(2,3-thiophenedithiol-
ate), TPP2Co(α-tpdt)2 (7): The compound was prepared using the
same method as for 4. The initial reactive was 5,6-thieno[2,3-d]-1,3-
dithiol-2-one (2). The product was obtained as dark brown crystals
after recrystallisation in acetonitrile/ethyl ether. Total yield: 80%,
214 mg; C56H44CoP2S6 (1030.20): calcd. C 65.29, H 4.30, S 18.67;
found C 64.90, H 3.95, S 18.75; ν = 3440 (m), 3050 (m) (C–H
˜
arom.), 1650 (m), 1640 (m), 1590 (s), 1490 (s), 1445 (s) (P-φ), 1310
(m), 1240 (m), 1160 (m), 1110 (s), 1020 (m), 1000 (m), 755 (m), 730
(s), 700 (s), 630 (m), 54 (s) cm–1. UV/Vis (CH3CN): λmax = 581,
795, 1912 nm; m.p. 117.8–119.5 °C. MS: m/z (%) = 144.7 (100)
[S3C4] [M–].
Bis(tetraphenylphosphonium) Salt of Platinum(II) Bis(2,3-thiophene-
dithiolate), TPP2Pt(α-tpdt)2 (8): The compound was prepared from
5,6-thieno[2,3-d]-1,3-dithiol-2-one (II) following the same method
as in 5. After recrystallisation the compound was obtained as
orange plate-shaped crystals. Yield: 53%, 161 mg; C56H44P2PtS6
(1166.36): calcd. C 57.67, H 3.80, S 16.49; found C 56.93, H 3.69,
Acknowledgments
This work was partially supported by Fundação para a Ciência e
Tecnologia (Portugal) under contracts POCTI/35342/QUI/2000
and POCTI/QUI/4508/2002 and by DGI project BQU2003–00760,
and by DGR Catalonia, project 2001SGR00362 (Spain). The col-
laboration between the team members of Sacavém and Barcelona
was supported under the CSIC-ICCTI bilateral agreement. This
work also benefited from COST action D14.
S 16.25; ν = 3054 (m) (C–H arom.), 1578 (m), 1429 (m) (P-φ), 1377
˜
(s), 716 (s) (C–S), 682 (s) (C–S) cm–1. UV/Vis (CH3CN): λmax
990, 1912 nm. MS: m/z (%) = 487.5 (100) [M–].
=
Bis(tetraphenylphosphonium) Salt of Copper(I) Tris(2,3-thiophenedi-
thiolate), TPP2Cu4(α-tpdt)3 (9): Using as starting material 2 and
following the same procedure used for 6, the product was obtained
as golden brown crystals. Yield: 59%, 53 mg; C60H46Cu4P2S9
(1371.69): calcd. C 52.54, H 3.38, S 21.03; found C 53.27, H 3.47,
[1] a) J. A. McCleverty, Prog. Inorg. Chem. 1968, 10, 29; b) D.
Coucouvanis, Prog. Inorg. Chem. 1970, 11, 233; c) R. Eisen-
berg, Prog. Inorg. Chem. 1971, 12, 295; d) L. Alcácer, H. Novais
in Extended Linear Chain Compounds (Ed.: J. S. Miller), Ple-
num Press, New York, 1983, vol. 3, ch. 6, p. 319; e) S. Alvarez,
V. Ramon, R. Hoffman, J. Am. Chem. Soc. 1985, 107, 6253; f)
Progress in Inorganic Chemistry, vol. 52, Dithiolene Chemistry:
S 20.35; ν = 1482 (m), 1439 (m) (P-φ), 1110 (m), 998 (m), 864 (m),
˜
757 (m), 726 (s) (C–S), 692 (s) (C–S), 601 (m), 514 (s) cm–1. UV/
Vis (CH3CN): λmax = 432, 1418, 1908 nm; m.p. 213.3–214.4 °C dec.
MS: m/z (%) = 144.9 [C4H2S3], 324.8 [C8H4S5Cu], 353 [C8H4S6Cu].
3344
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 3337–3345

Copper, Cobalt and Platinum Complexes with Dithiothiophene-Based Ligands
FULL PAPER
Synthesis Properties, and Applications (Eds.: K. D. Karlin, E. I.
Tiefel), John Wiley & Sons, New York, 2004.
[10] D. Belo, H. Alves, E. B. Lopes, M. T. Duarte, V. Gama, R. T.
Henriques, M. Almeida, A. Pérez-Benítez, C. Rovira, J. Veci-
ana, Chem. Eur. J. 2001, 7, 511–519.
[2] N. Robertson, L. Cronin, Coord. Chem. Rev. 2002, 227, 93.
[3] A. T. Coomber, D. Beljonne, R. H. Friend, J. L. Bredas, A. [11] D. Belo, H. Alves, S. Rabaça, L. C. Pereira, M. T. Duarte, V.
Charlton, N. Robertson, A. E. Underhill, M. Kurmoo, P. Day,
Nature 1996, 380, 144.
[4] a) M. Ahmad, A. E. Underhill, J. Chem. Soc., Chem. Commun.
1981, 67; b) M. M. Ahmad, D. J. Turner, A. E. Underhill, C. S.
Jacobsen, K. Mortensen, K. Carneiro, Phys. Rev. B 1984, 29,
4796.
[5] a) P. Cassoux, L. Valade in Inorganic Materials, 2nd ed. (Eds.:
D. W. Bruce, D. O’Hare), John Wiley & Sons, Chichester, 1996,
pp. 1–64; b) P. Cassoux, J. S. Miller in Chemistry of Advanced
Materials (Eds.: L. V. Interrante, M. J. Hampden-Smith),
Wiley-VCH, New York, 1998, pp. 19–72.
Gama, R. T. Henriques, M. Almeida, E. Ribera, C. Rovira, J.
Veciana, Eur. J. Inorg. Chem. 2001, 3127–3132.
[12] H. Tanaka, Y. Okano, H. Kobayashi, W. Susuki, A. Kobayashi,
Science 2001, 291, 285.
[13] a) G.-E. Matsubayashy, A. Yokozawa, Chem. Commun. 1991,
68; b) J. Dai, M. Munakata, Y. Ohno, G. Q. Bian, Y. Suenaga,
Inorg. Chim. Acta 1999, 285, 332; c) J. R. Nicholson, I. L.
Abrahams, C. D. Garner, Inorg. Chem. 1985, 24, 1092.
[14] A. Altomare, M. C. Burla, M. Camalli, G. Cascarano, G. Gia-
covazzo, A. Guagliardi, A. G. G. Moliterni, G. Polidori, R.
Spagna, J. Appl. Cryst. 1999, 32, 115–119.
[6] D. Simão, H. Alves, D. Belo, S. Rabaça, E. B. Lopes, V. Gama, [15] G. M. Sheldrick, SHELXL97, A Program for Crystal Structure
M. T. Duarte, R. T. Henriques, H. Novais, M. Almeida, Eur. J.
Inorg. Chem. 2001, 3119–3126.
[7] H. Alves, D. Simão, I. C. Santos, V. Gama, R. T. Henriques,
H. Novais, M. Almeida, Eur. J. Inorg. Chem. 2004, 6, 1318–
1329.
[8] V. Gama, R. T. Henriques, M. Almeida, L. Veiros, M. J. Cal-
horda, A. Meetsma, J. L. de Boer, Inorg. Chem. 1993, 32, 3705–
3711.
Refinement, University of Göttingen, Germany, 1997.
[16] L. J. Farrugia, J. Appl. Cryst. 1999, 32, 837–838.
[17] ORTEP3 for Windows: L. J. Farrugia, J. Appl. Crystallogr.
1997, 30, 565.
[18] E. Keller, SCHAKAL-97, A Computer Program for the Repre-
sentation of Molecular and Crystallographic Models, Kristal-
lographisches Institut der Universität Freiburg, Germany,
1997.
[9] V. Gama, R. T. Henriques, G. Bonfait, M. Almeida, A. [19] L. Persaud, C. H. Langford, Inorg. Chem. 1985, 24, 3562.
Meetsma, S. Van Smaalen, J. L. de Boer, J. Am. Chem. Soc.
1992, 114, 1986–1989.
Received: February 16, 2005
Published Online: July 4, 2005
Eur. J. Inorg. Chem. 2005, 3337–3345
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3345