Metal complexes of dithiolate ligands: 5,6-dihydro-l,4-dithiin-2,3-dithiolato (dddt2-), 5,7-dihydro-l,4,6-trithiin-2,3-dithiolato (dtdt2-), and 2-thioxo-1,3-dithiole-4,5-dithiolato (dmit2-). Synthesis, electrochemical studies, crystal and electronic structures, and conducting properties

Article abstract of DOI:10.1021/ic9600341

New precursors to potentially conductive noninteger oxidation state (NIOS) compounds based on metal complexes [ML₂]ⁿ [M = Ni, Pd, Pt; L = 5,6-dihydro-1,4-dithiin-2,3-dithiolato (dddt^2-), 5,7-dihydro-1,4,6-trithiin-2,3-dithiolato (dtdt^2-), and 2-thioxo-1,3-dithiole-4,5-dithiolato (dmit^2-); n = 2, 1,0] have been investigated. Complexes of the series (NR₄)[ML₂] (R = Me, Et, Bu; L = dddt^2-, dtdt^2-) have been isolated and characterized, and the crystal structure of (NBu₄)[Pt(dtdt)₂] (1) has been determined (1 = C₂₄H₄₄NPtS₁₀, a -12.064(2) ?, b = 17.201(3) ?, c = 16.878(2) ?, β= 102.22(2)?, V= 3423(1) ?³, monoclinic, P2₁/n, Z = 4}. Oxidation of these complexes affords the corresponding neutral species [ML₂]⁰. Another series of general formula (cation)_n[M(dmit)₂] [cation = PPN⁺, BTP⁺, and (SMe_yEt_3-v)⁺ with y = 0, 1, 2, and 3, n = 2, 1, M = Ni, Pd] has also been studied. All of these (cation)_n[M(dmit)₂] complexes have been isolated and characterized [with the exception of (cation)[Pd-(dmit)₂] for cation = (SMe_yEt_3-v)⁺]. The crystal structures of (PPN)LNi(dmit)₂]·(CH₃)₂CO (2) and (SMeEt₂)[Ni(dmit)₂] (3) have been determined {2 = C₄₅H₃₆NNiS₁₀P₂O, a = 12.310(2) ?, b = 13.328(3) ?, c = 15.850(3) ?, α = 108.19(3)°, β= 96.64(2)°, γ = 99.67(2)°, V = 2373(1) ?³, triclinic, Pī, Z = 2; 3 = C₁₁M₁₃NiS₁₁, a = 7.171(9) ?, b = 17.802(3) ?, c = 16.251(3) ?, β = 94.39(4)°, V = 2068(2) ?³, monoclinic, P2₁/n, Z = 4} NIOS salts derived from the preceding precursors were obtained by electrochemical oxidation. Electrochemical studies of the [M(dddt)₂] complexes show that they may be used for the preparation of NIOS radical cation salts and [M(dddt)₂][M'(dmit)₂]_x compounds, but not for the preparation of (cation)[M(dddt)₂]_z NIOS radical anion salts. The electrochemical oxidation of the [M(dtdt)₂]^- complexes always yields the neutral [M(dtdt)₂]⁰ species. The crystal structure of [Pt(dddt)₂][Ni(dmit)₂]₂ (4) has been determined and is consistent with the low compaction powder conductivity (5 × 10^-5 S cm^-1 at room temperature) {4 = C₂₀H₈Ni₂PtS₂₈, a = 20.336(4) ?, b = 7.189(2) ?, c = 14.181(2) ?, β = 97.16(2)°, V = 2057(1) ?³, monoclinic, C2/m, Z = 2}. The crystal structures of the semiconducting NIOS compounds (BTP)[Ni(dmit)₂]₃ (5) and (SMe₃)[Ni(dmit)₂]₂ (6) have been determined {5 = C₄₃H₂₂PNi₃S₃₀, a = 11.927(2) ?, b = 24.919(2) ?, c = 11.829(3) ?, α = 93.11(1)°, β= 110.22(1)°, γ = 83.94(1)°, V = 3284(1) ?3, triclinic, Pī, Z = 2; 6 = C₁₅H₉Ni₂S₂₁, a = 7.882(1) ?, b = 11.603(2) ?, c = 17.731(2) ?, α = 77.44(1)°, β= 94.39(1)°, γ = 81.27(1)°, V = 1563(1) ?³, triclinic, Pī, Z = 2}. The parent compound (SEt₃)[Ni(dmit)₂]_z (unknown stoichiometry) is also a semiconductor with a single-crystal conductivity at room temperature of 10 S cm^-1. By contrast, the single-crystal conductivity at room temperature of (SMeEt₂)[Pd(dmit)₂]₂ (7) is rather high (100 S cm^-1). 7 behaves as a pseudometal down to 150 K and undergoes an irreversible metal-insulator transition below this temperature. The crystal structure of 7 has been determined {7 = C₁₇H₁₃NPd₂S₂₁, a = 7.804(4) ?, b = 36.171(18) ?, c = 6.284(2) ?, α = 91.68(4)°, β= 112.08(4)°, γ = 88.79(5)°, V = 1643(1) ?3, triclinic, P1?. Z = 2}. The electronic structure of (SMeEt₂)[Pd(dmit)₂]₂ (7) and the possible origin of the metal-insulator transition at 150 K are discussed on the basis of tight-binding band structure calculations.

Full text of DOI:10.1021/ic9600341

3856
Inorg. Chem. 1996, 35, 3856-3873
Metal Complexes of Dithiolate Ligands: 5,6-Dihydro-1,4-dithiin-2,3-dithiolato (dddt2-),
5,7-Dihydro-1,4,6-trithiin-2,3-dithiolato (dtdt2-), and 2-Thioxo-1,3-dithiole-4,5-dithiolato
(dmit2-). Synthesis, Electrochemical Studies, Crystal and Electronic Structures, and
Conducting Properties
Christophe Faulmann,1a Ahmed Errami,1a Bruno Donnadieu,1a Isabelle Malfant,1a
Jean-Pierre Legros,1a Patrick Cassoux,*,1a Carme Rovira,1b and Enric Canadell1c
Equipe Pre´curseurs Mole´culaires et Mate´riaux, Laboratoire de Chimie de Coordination du CNRS lie´ par
convention a` l’Universite´ Paul Sabatier, 205 Route de Narbonne, 31077 Toulouse Cedex, France,
Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, 08028 Barcelona, Spain,
Institut de Ciencia de Materials de Barcelona, Campus de la UAB, 08193 Bellaterra, Spain, and
Laboratoire de Chimie The´orique (CNRS URA 506), Universite´ de Paris-Sud,
91405 Orsay Cedex, France
ReceiVed January 11, 1996X
New precursors to potentially conductive noninteger oxidation state (NIOS) compounds based on metal complexes
[ML2]n- [M ) Ni, Pd, Pt; L ) 5,6-dihydro-1,4-dithiin-2,3-dithiolato (dddt2-), 5,7-dihydro-1,4,6-trithiin-2,3-
dithiolato (dtdt2-), and 2-thioxo-1,3-dithiole-4,5-dithiolato (dmit2-); n ) 2, 1, 0] have been investigated. Complexes
of the series (NR4)[ML2] (R ) Me, Et, Bu; L ) dddt2-, dtdt2-) have been isolated and characterized, and the
crystal structure of (NBu4)[Pt(dtdt)2] (1) has been determined {1 ) C24H44NPtS10, a ) 12.064(2) Å, b ) 17.201-
(3) Å, c ) 16.878(2) Å, â ) 102.22(2)°, V ) 3423(1) Å3, monoclinic, P21/n, Z ) 4}. Oxidation of these complexes
affords the corresponding neutral species [ML2]0. Another series of general formula (cation)n[M(dmit)2] [cation
) PPN+, BTP+, and (SMeyEt3-y)+ with y ) 0, 1, 2, and 3, n ) 2, 1, M ) Ni, Pd] has also been studied. All of
these (cation)n[M(dmit)2] complexes have been isolated and characterized [with the exception of (cation)[Pd-
(dmit)2] for cation ) (SMeyEt3-y)+]. The crystal structures of (PPN)[Ni(dmit)2]‚(CH3)2CO (2) and (SMeEt2)-
[Ni(dmit)2] (3) have been determined {2 ) C45H36NNiS10P2O, a ) 12.310(2) Å, b ) 13.328(3) Å, c ) 15.850(3)
Å, R ) 108.19(3)°, â ) 96.64(2)°, γ ) 99.67(2)°, V ) 2373(1) Å3, triclinic, P1h, Z ) 2; 3 ) C11H13NiS11, a )
7.171(9) Å, b ) 17.802(3) Å, c ) 16.251(3) Å, â ) 94.39(4)°, V ) 2068(2) Å3, monoclinic, P21/n, Z ) 4} NIOS
salts derived from the preceding precursors were obtained by electrochemical oxidation. Electrochemical studies
of the [M(dddt)2] complexes show that they may be used for the preparation of NIOS radical cation salts and
[M(dddt)2][M′(dmit)2]x compounds, but not for the preparation of (cation)[M(dddt)2]z NIOS radical anion salts.
The electrochemical oxidation of the [M(dtdt)2]- complexes always yields the neutral [M(dtdt)2]0 species. The
crystal structure of [Pt(dddt)2][Ni(dmit)2]2 (4) has been determined and is consistent with the low compaction
powder conductivity (5 × 10-5 S cm-1 at room temperature) {4 ) C20H8Ni2PtS28, a ) 20.336(4) Å, b ) 7.189-
(2) Å, c ) 14.181(2) Å, â ) 97.16(2)°, V ) 2057(1) Å3, monoclinic, C2/m, Z ) 2}. The crystal structures of
the semiconducting NIOS compounds (BTP)[Ni(dmit)2]3 (5) and (SMe3)[Ni(dmit)2]2 (6) have been determined
{5 ) C43H22PNi3S30, a ) 11.927(2) Å, b ) 24.919(2) Å, c ) 11.829(3) Å, R ) 93.11(1)°, â ) 110.22(1)°, γ )
83.94(1)°, V ) 3284(1) Å3, triclinic, P1h, Z ) 2; 6 ) C15H9Ni2S21, a ) 7.882(1) Å, b ) 11.603(2) Å, c )
17.731(2) Å, R ) 77.44(1)°, â ) 94.39(1)°, γ ) 81.27(1)°, V ) 1563(1) Å3, triclinic, P1h, Z ) 2}. The parent
compound (SEt3)[Ni(dmit)2]z (unknown stoichiometry) is also a semiconductor with a single-crystal conductivity
at room temperature of 10 S cm-1. By contrast, the single-crystal conductivity at room temperature of (SMeEt2)-
[Pd(dmit)2]2 (7) is rather high (100 S cm-1). 7 behaves as a pseudometal down to 150 K and undergoes an
irreversible metal-insulator transition below this temperature. The crystal structure of 7 has been determined {7
) C17H13NPd2S21, a ) 7.804(4) Å, b ) 36.171(18) Å, c ) 6.284(2) Å, R ) 91.68(4)°, â ) 112.08(4)°, γ )
88.79(5)°, V ) 1643(1) Å3, triclinic, P1h, Z ) 2}. The electronic structure of (SMeEt2)[Pd(dmit)2]2 (7) and the
possible origin of the metal-insulator transition at 150 K are discussed on the basis of tight-binding band structure
calculations.
Introduction
charge transfer salts of only six organic molecules derived from
tetrathiafulvalene (TTF), namely, MDT-TTF, TMTSF, BEDT-
TTF, BEDO-TTF, BEDT-TSF, and DMET.3,4 The largest
family of organic molecule-based superconductors comprises
Most molecule-based superconductors, except the doped
fullerenes AxC60 (A ) alkali and alkaline earth metals),2 are
X Abstract published in AdVance ACS Abstracts, May 15, 1996.
(1) (a) Equipe Pre´curseurs Mole´culaires et Mate´riaux. (b) Departament
de Quimica Fisica. (c) Institut de Ciencia de Materials de Barcelona
and Laboratoire de Chimie The´orique.
(2) (a) Hebard, A. F.; Rosseinsky, M. J.; Haddon, R. C.; Murphy, D. W.;
Glarum, S. H.; Palstra, T. T. M.; Ramirez, A. P.; Kortan, A. R. Nature
1991, 350, 600. (b) Hebard, A. F. Phys. B 1994, 197,544.
(3) Williams, J. M.; Ferraro, F. R., Thorn, R. J.; Carlson, K. D.; Geiser,
U.; Wang, H. H.; Kini, A. M.; Whangbo, M.-H. Organic Supercon-
ductors (Including Fullerenes); Prentice Hall: Englewood Cliffs, NJ,
1992.
(4) Cassoux, P.; Miller, J. S. in Chemistry of AdVanced Materials: A New
Discipline; Interrante, L. V., Hampden-Smith, M., Eds.; VCH Publish-
ers: New York, in press.
S0020-1669(96)00034-1 CCC: $12.00 © 1996 American Chemical Society

Metal Complexes of Dithiolate Ligands
Inorganic Chemistry, Vol. 35, No. 13, 1996 3857
the (BEDT-TTF)2X salts [BEDT-TTF ) bis(ethylenedithio)-
tetrathiafulvalene; X ) anions such as I3-, [Cu(NCS)2]-, and
{Cu[N(CN)2]Cl}-].3
behavior compared to that of analogue complexes of the dmit2-
ligand, the tentative preparation of their derived charge transfer
salts, and the preparation, crystal and electronic structure, and
conducting properties of new charge transfer salts of metal (Ni,
Pd) complexes of the dmit2- ligand using PPN+ [bis(triph-
enylphosphoranylidene)], BTP+ (benzyltriphenylphosphonium),
and the sulfonium cations of the (SMeyEt3-y)+ series with y )
0, 1, 2, and 3 as countercations.
Yet, inorganic compounds, namely, the partially oxidized
platinum complexes K2[Pt(CN)4]X0.3‚3H2O (X ) Cl, Br),5 were
among the first molecule-based metal-like conductors. Other
inorganic molecule-based systems have also been used for the
fabrication of materials exhibiting high conductivities, including
linear-chain iridium complexes,6 macrocyclic metal complexes
such as those derived from glyoximate and tetraazaannulene
ligands,7-9 metalloporphyrins,7,10 DCNQI metal complexes,11,12
and metal complexes of dithiolate ligands.13,14 However,
superconductivity has been observed in only seven charge
transfer salts of metal complexes of just one 1,2-dithiolate
ligand, the dmit2- ligand (dmit2- ) 2-thioxo-1,3-dithiole-4,5-
Experimental Section
Syntheses. All syntheses were carried out by using vacuum line
and Schlenk techniques in a dried N2 atmosphere. The main starting
dmit-based compounds, e.g., (NBu4)2[Zn(dmit)2],26 dmit(COPh)2,26
dmitNa2,27 and (NR4)[M(dmit)2],14 were prepared as previously de-
scribed.
(NR4)[M(dddt)2]. These complexes (M ) Ni, Pd, Pt) were obtained
by hydrolysis of the C5H4S5 thione (5,6-dihydro-1,3-dithiolo[4,5,6][1,4]-
dithiin-2-thione),27 affording the K2dddt salt,28,29 subsequent complex-
ation with an appropriate metal salt, and precipitation with NR4Br (R
) Et, Bu), following previously reported procedures.29-31 In the case
of the nickel complex, a mixture of the divalent (NBu4)2[Ni(dddt)2]
and monovalent (NBu4)[Ni(dddt)2] complexes is obtained. Separation
of these complexes by recrystallization failed, and oxidation by bubbling
air through the reaction mixture for 15 min is required to obtain the
pure monovalent salt. Only the monovalent (NBu4)[Pt(dddt)2] and
(NEt4)[Pd(dddt)2] complexes can be obtained, even under N2 atmo-
sphere. The preparation of (NEt4)[Pd(dddt)2] is difficult because of
its instability in the generally used water/ethanol medium. This
complex is best obtained when THF is used as solvent and bis-
(benzonitrile)dichloropalladium(II) [(C6H5CN)2PdCl2]32 is used as the
palladium source. Thus, the formation of metallic sulfides observed
when K2PdCl4 or PdCl2 is used in water/ethanol30 may be avoided.
The (NR4)[M(dddt)2] complexes were recrystallized in acetone/2-
propanol (1/1) and characterized by elemental analysis and infrared
spectroscopy (supplementary material, Table S1).
dithiolato).15 Three of these superconducting salts, (NMe4)0.5
-
[Ni(dmit)2],16 â-(NMe4)0.5[Pd(dmit)2],17 and [NMe2Et2]0.5[Pd-
(dmit)2],18 contain closed-shell cations, and four, (TTF)-
[Ni(dmit)2]2,19 R- and R′-(TTF)[Pd(dmit)2]2,20,21 and R-(EDT-
TTF)[Ni(dmit)2],22 contain open-shell cations.
With the aim of extending the range of conductors and
possibly superconductors in this series, extensive studies have
been carried out on M(dmit)2-related systems obtained not only
by changing the nature of the metal and the countercation14,15
but also by using other ligands resembling dmit2-, such as, for
example, selenium-substituted dmit2- ligands,23 1,2,5-thiadia-
zole-3,4-dithiolato (tdas2-),24 and dimercaptobenzeneisotrithione
(dmbit2-).25
Along the same line, we report here on the synthesis and
crystal structure of metal (Ni, Pd, Pt) complexes of two 1,2-
dithiolate ligands resembling dmit2-, the 5,6-dihydro-1,4-dithiin-
2,3-dithiolato (dddt2-) and 5,7-dihydro-1,4,6-trithiin-2,3-dithi-
olato (dtdt2-) ligands. We also report on their electrochemical
[M(dddt)2]0.33-35 The derived neutral complexes (M ) Ni, Pt) were
obtained31 by chemical oxidation of the corresponding monovalent
complexes by tetracyanoquinodimethane. They were characterized by
elemental analysis and infrared spectroscopy (supplementary material,
Table S1).
(5) Williams, J. M.; Schultz, A. J.; Underhill, A. E.; Carneiro, K. In
Extended Linear Chain Compounds; Miller, J. S., Ed.; Plenum Press:
New York, 1982; Vol. 1, pp 73-118.
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Yagubskii, E. B.; Faulmann, C.; Cassoux, P. J. Chem. Soc., Chem.
Commun. 1993, 508. (b) Awaga, K.; Okuno, T.; Maruyama, Y.;
Kobayashi, A.; Kobayashi, H.; Schenk, S.; Underhill, A. E. Inorg.
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Trans. 1985, 783.
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3858 Inorganic Chemistry, Vol. 35, No. 13, 1996
Faulmann et al.
Table 1. Crystallographic Data for (NBu4)[Pt(dtdt)2] (1), (PPN)[Ni(dmit)2]‚(CH3)2CO (2), (SMeEt2)[Ni(dmit)2] (3), [Pt(dddt)2][Ni(dmit)2]2 (4),
(BTP)[Ni(dmit)2]3 (5), (SMe3)[Ni(dmit)2]2 (6), and (SMeEt2)[Pd(dmit)2]2 (7)
compound
1
2
3
4
5
6
7
chem formula
fw
space group
a (Å)
b (Å)
c (Å)
C24H44NPtS10
862.3
P21/n
12.064(2)
17.201(3)
16.878(2)
C45H36NNiS10P2O
1048.0
P1h
C11H13NiS11
556.6
P21/n
7.171(9)
17.802(3)
16.251(3)
C20H8Ni2PtS28
1458.5
C2/m
20.336(4)
7.189(2)
14.181(2)
C43H22PNi3S30
1707.5
P1h
C15H9Ni2S21
971.9
P1h
C17H13Pd2S21
1103.4
P1h
12.310(2)
13.328(3)
15.850(3)
108.19(3)
96.64(2)
99.67(2)
2373(1)
1.367
2
9.3
0.057
0.068
11.927(2)
24.919(2)
11.829(3)
93.11(1)
110.22(1)
83.94(1)
3284(1)
1.73
2
18.3
0.049
0.051
7.882(1)
11.603(2)
17.731(2)
77.44(1)
94.39(1)
81.27(1)
1563(1)
2.08
2
25.7
0.075
0.084
7.804(4)
36.171(18)
6.284(2)
91.68(4)
112.08(4)
88.79(5)
1643(1)
2.23
2
23.8
0.074
0.079
R (deg)
â (deg)
γ (deg)
V (Å3)
102.22(2)
94.39(4)
97.16(2)
3423(1)
1.674
4
47.5
0.031
0.035
2068(2)
1.788
4
20.1
0.031
0.033
2057(1)
2.36
2
57.3
0.047
0.049
F
Z
calcd (g cm-3
)
µ(Mo KR) (cm-1
R(Fo)a
)
Rw(Fo)a
2
a R(Fo) ) ∑(||Fo| - |Fc||)/∑|Fo| and Rw(Fo) ) [∑w(|Fo| - |Fc|)2/∑wFo ]1/2
.
(NR4)[M(dtdt)2]. These complexes (M ) Ni, Pd, Pt) were obtained
by following a method, similar to that used for the (NR4)2[Ni(dddt)2]
complexes, based on the hydrolysis of the C5H4S6 thione (1,3-[4,5-f]-
[1,3,5]trithiepin-2-thione),36 affording the K2dtdt salt, and subsequent
metal complexation.
(NMe4)[Ni(dtdt)2]. Recrystallization of this complex, obtained as
in ref 29 and precipitated by using NMe4Br instead of NBu4Br,
succeeded in a mixture of acetone/2-propanol (1/1).
complexes by oxidation with I2/NaI.14,26,31 All complexes were
recrystallized in acetone/2-propanol (1/1) and characterized by elemental
analysis and infrared spectroscopy (supplementary material, Table S1).
(PPN)[Ni(dmit)2]‚(CH3)2CO (2) and (SMeEt2)[Ni(dmit)2] (3) were
further characterized by determination of their crystal structures by
X-ray diffraction methods (Vide infra). In the series of palladium
complexes with the cation (SMeyEt3-y)+, iodine oxidation of the divalent
(SMeyEt3-y)2[Pd(dmit)2] complexes leads to the formation of insoluble
solids [probably noninteger oxidation state (NIOS) compounds of the
type (SMeyEt3-y)[Pd(dmit)2]z], and the corresponding monovalent
(SMeyEt3-y)[Pd(dmit)2] complexes could not be isolated. This is related
to the redox properties of these systems (Vide infra).
Electrocrystallization. [M(dddt)2][M′(dmit)2]x complexes (M ) Ni,
Pt; M′ ) Ni, Pd) have been prepared by galvanostatic (1-6 µA/cm2)
electrochemical oxidation on a platinum electrode from solutions of
[M(dddt)2]0 and (NBu4)[M′(dmit)2] in an appropriate solvent and
characterized by elemental analysis (supplementary material, Table S2).
[Pt(dddt)2][Ni(dmit)2]2 (4) was further characterized by determination
of its crystal structure by X-ray diffraction methods (Vide infra).
Likewise, the (cation)[M(dmit)2]z NIOS salts were obtained by
galvanostatic (1-3 µA/cm2) electrochemical oxidation of solutions of
the appropriate monovalent [or divalent in the case of the
(SMeyEt3-y)2[Pd(dmit)2] series] complexes, following previously
reported procedures,15 and characterized by elemental analysis (supple-
mentary material, Tables S3 and S4). Compounds (BTP)[Ni(dmit)2]3
(5), (SMe3)[Ni(dmit)2]2 (6), and (SMeEt2)[Pd(dmit)2]2 (7) were further
characterized by determination of their crystal structures by X-ray
diffraction methods (Vide infra).
(NBu4)[Pt(dtdt)2] (1). C5H4S6 (1 g, 3.9 mmol) was treated with 2
g (36 mmol) of KOH in 20 mL of ethanol. The solution was stirred
at 50 °C for 1.5 h. The mixture was cooled down to room temperature
and filtered, and the pale yellow crystals of K2dtdt were washed with
ethanol (three portions of 4 mL) and dried under vacuum. The K2dtdt
salt was dissolved in 40 mL of a water/ethanol (1/1) mixture and treated
dropwise with 0.8 g (1.9 mmol) of K2PtCl4 in 30 mL of water. After
30 min of stirring, 0.7 g (2.2 mmol) of NBu4Br in 20 mL of water was
added to the solution. The dark green precipitate was isolated by
filtration, washed with ethanol, and dried under vacuum. Recrystal-
lization in acetone/2-propanol (1/1) afforded 0.50 g of dark green
crystals.
(NBu4)[Pd(dtdt)2]. The K2dtdt salt obtained as in the preceding
paragraph was dissolved in 100 mL of THF and treated dropwise with
0.75 g (1.95 mmol) of (C6H5CN)2PdCl2 in 50 mL of THF. The brown
mixture turned dark green during the addition. The solution was stirred
for an additional 30 min. NBu4Br (0.63 g, 1.95 mmol) in 50 mL of
water was then added dropwise. After concentration of the solution
with a rotary evaporator and filtration, a brown green precipitate was
obtained, which was washed with 20 mL of methanol. Recrystallization
in a mixture of acetone/2-propanol (1/1) afforded 0.40 g of brown green
crystals.
Electrochemical Studies. Slow (V < 1 V s-1) and fast (V > 1 V
s-1 and up to 1000 V.s-1) voltammetric measurements and controlled
potential electrolysis were carried out with an ISMP Model Elektroke-
mat 400 microcomputer-controlled instrumentation with positive feed-
back ohmic resistance compensation,37 following previously described
techniques.38,39
These (NR4)[M(dtdt)2] complexes were characterized by elemental
analysis and infrared spectroscopy (supplementary material, Table S1).
The (NBu4)[Pt(dtdt)2] complex (1) was further characterized by X-ray
crystal structure determination (Vide infra).
(cation)2[M(dmit)2] (M ) Ni, Pd). The cations used in this work
were PPN+ [bis(triphenylphosphoranylidene)], BTP+ (benzyltriph-
enylphosphonium), and the sulfonium cations of the (SMeyEt3-y)+ series
with y ) 0, 1, 2, and 3. The (cation)2[M(dmit)2] divalent complexes
were prepared by the now standard one-pot method,14,26 involving
generation of the dmit2- ligand in a methanol solution by reaction of
dmit(COPh)2 with methanolate, reaction of an appropriate metal salt
(NiCl2‚6H2O or Na2PdCl4, respectively), and precipitation in the final
step of the desired (cation)2[M(dmit)2] complex by addition of the
chloride of the appropriate cation.31 All complexes were recrystallized
in acetone/2-propanol (1/1) and characterized by elemental analysis
and infrared spectroscopy (supplementary material, Table S1).
(cation)[M(dmit)2]. These monovalent complexes (M ) Ni and
the same cations as before; M ) Pd and cation ) PPN+ and BTP+)
were obtained from the corresponding divalent (cation)2[M(dmit)2]
X-ray Diffraction Data Collection and Structure Determination.
All data were collected at room temperature on an Enraf-Nonius CAD4
diffractometer with graphite-monochromated Mo KR radiation (λ )
0.710 73 Å) by using the CAD4-Express package.40 For every
compound, the intensity of three reflections was monitored throughout
the data collection, and no significant decay was observed. Accurate
unit cell parameters were obtained by least-squares refinements on the
basis of the setting angles of 25 reflections, unless otherwise specified.
Crystallographic data for (NBu4)[Pt(dtdt)2] (1), (PPN)[Ni(dmit)2]‚(CH3)2-
CO (2), (SMeEt2)[Ni(dmit)2] (3), [Pt(dddt)2][Ni(dmit)2]2 (4), (BTP)-
(37) Cassoux, P.; Dartiguepeyron, R.; David, C.; de Montauzon, D.;
Tommasino, J.-B.; Fabre, P.-L. L’Actual. Chim. 1994, 1-2, 49.
(38) Tommasino, J.-B.; Pomarede, B.; Medus, D.; de Montauzon, D.;
Cassoux, P. Mol. Cryst. Liq. Cryst. 1993, 237, 445.
(39) Faulmann, C.; Cassoux, P.; Yagubskii, E. B.; Vetoshkina, L. V. New
J. Chem. 1993, 17, 385.
(40) Enraf-Nonius, CAD4-Express, version 5.1, Delft, Holland, 1992.
(36) Russkikh, V. S.; Abashev, G. G. Khim. Geterotsikl. Soedin 1987, 11,
1483.

Metal Complexes of Dithiolate Ligands
Inorganic Chemistry, Vol. 35, No. 13, 1996 3859
Table 2. Atomic Parameters for (NBu4)[Pt(dtdt)2] (1)
Table 3. Atomic Parameters for (PPN)[Ni(dmit)2]‚(CH3)2CO] (2)
atom
x/a
y/b
z/c
Ueqa (Å2)
atom
x/a
y/b
z/c
Ueqa/Uiso (Å2)
Pt(1)
S(1)
S(2)
S(3)
S(4)
S(5)
S(6)
S(7)
S(8)
0.14950(3)
0.0381(2)
0.2434(2)
0.0115(2)
0.2326(3)
0.2039(3)
0.2700(2)
0.0538(2)
0.3184(2)
0.0891(3)
0.1445(3)
0.3278(6)
0.0867(8)
0.1771(8)
0.1113(9)
0.2927(9)
0.1349(9)
0.2285(8)
0.042(1)
0.86428(2)
0.7577(2)
0.8236(2)
0.6259(2)
0.6928(2)
0.5205(2)
0.9657(2)
0.9038(2)
1.0778(2)
1.0127(2)
0.1866(2)
0.0810(4)
0.7104(6)
0.7389(6)
0.5486(6)
0.6047(7)
0.9790(6)
1.1097(8)
1.1097(8)
0.1657(6)
1.1279(6)
0.1094(6)
0.1682(7)
0.1546(8)
-0.0058(5)
-0.0345(6)
-0.1199(7)
-0.1574(8)
0.0916(7)
0.1742(8)
0.1755(9)
0.254(1)
0.86803(3)
0.8609(2)
0.9913(2)
0.9646(2)
1.1009(2)
1.0516(2)
0.8690(2)
0.7451(2)
0.7486(2)
0.6199(2)
0.6457(2)
0.1355(5)
0.9508(6)
1.0076(6)
0.9594(6)
1.0702(7)
0.7209(6)
0.6367(8)
0.6367(8)
0.7413(7)
0.2087(6)
0.2475(6)
0.3134(6)
0.3552(8)
0.1539(6)
0.2204(6)
0.2363(7)
0.2928(8)
0.0660(6)
0.0415(7)
-0.0388(7)
-0.0681(9)
0.1127(7)
0.0347(8)
0.0324(8)
-0.1021(8)
0.0404
0.0529
0.0493
0.0597
0.0565
0.0677
0.0481
0.0575
0.0550
0.0685
0.0757
0.0413
0.0479
0.0455
0.0479
0.0613
0.0516
0.0770
0.0770
0.0626
0.0483
0.0532
0.0540
0.0742
0.0447
0.0530
0.0684
0.0733
0.0494
0.0656
0.0748
0.0824
0.0560
0.0680
0.0889
0.0756
Ni(1)
S(1)
S(2)
S(3)
S(4)
S(5)
S(6)
S(7)
S(8)
S(9)
S(10)
N(1)
P(1)
P(2)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
0.48375(8) 0.09063(8) 0.34413(7)
0.0405
0.0495
0.0503
0.0558
0.0557
0.0796
0.0497
0.0502
0.0562
0.0578
0.0736
0.0391
0.0367
0.0371
0.0460
0.0441
0.3206(2)
0.4436(2)
0.1184(2)
0.2312(2)
0.0005(2)
0.6428(2)
0.5284(2)
0.8434(2)
0.7389(2)
0.9686(2)
0.3721(5)
0.2433(2)
0.4541(2)
0.2548(7)
0.3084(6)
0.1108(7)
0.7099(7)
0.6584(6)
0.8563(7)
0.1609(6)
0.2055(6)
0.1424(7)
0.0333(7)
0.1106(2)
0.1050(2)
0.1433(2)
0.1361(2)
0.1745(3)
0.0616(2)
0.0869(2)
0.0226(2)
0.0489(2)
0.0084(2)
0.6138(4)
0.5980(1)
0.5531(2)
0.1244(6)
0.1218(6)
0.1528(7)
0.0494(6)
0.0599(5)
0.0257(6)
0.6012(6)
0.6670(6)
0.6770(7)
0.6222(7)
0.5665(7)
0.5440(7)
0.4760(6)
0.3772(7)
0.2816(9)
0.286(1)
0.2936(1)
0.4760(1)
0.3830(1)
0.5506(1)
0.5400(2)
0.3929(1)
0.2151(1)
0.3020(2)
0.1401(1)
0.1506(2)
0.8341(4)
0.8352(1)
0.7760(1)
0.3846(5)
0.4637(5)
0.4945(6)
0.3018(6)
0.2246(5)
0.1949(6)
0.7351(5)
0.6907(5)
0.6169(6)
0.5895(6)
0.6336(6)
0.7056(6)
0.8554(5)
0.7855(6)
0.8040(7)
0.8903(9)
0.9603(9)
0.9420(7)
0.9271(5)
0.9932(6)
1.0646(6)
1.0682(6)
1.0038(6)
0.9321(6)
0.6577(4)
0.6247(5)
0.5367(6)
0.4837(6)
0.5159(6)
0.6030(5)
0.7896(5)
0.8723(6)
0.8866(7)
0.8187(7)
0.7392(7)
0.7235(5)
0.8142(5)
0.8780(5)
0.9058(6)
0.8707(6)
0.8084(6)
0.7813(6)
0.2889(8)
0.335(1)
S(9)
S(10)
N(1)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
0.0534
0.0443
0.0408
0.0541
C(8)
C(9)
0.234(1)
0.3825(8)
0.5052(9)
0.5487(9)
0.671(1)
0.3345(8)
0.2808(9)
0.308(1)
0.245(1)
0.3885(9)
0.404(1)
0.440(1)
0.465(1)
0.2045(9)
0.132(1)
0.105(1)
0.036(2)
0.043(2)
0.055(2)
0.060(2)
0.065(2)
0.053(2)
0.045(2)
0.057(2)
0.080(3)
0.110(4)
0.114(4)
0.081(3)
0.036(2)
0.054(2)
0.069(3)
0.060(2)
0.067(2)
0.059(2)
0.034(2)
0.045(1)
0.057(2)
0.062(2)
0.060(2)
0.045(2)
0.044(2)
0.062(2)
0.083(3)
0.082(3)
0.073(3)
0.052(2)
0.043(2)
0.049(2)
0.063(2)
0.067(2)
0.071(3)
0.061(2)
0.089(3)
0.184(7)
0.163(6)
0.1584
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(19)
C(20)
C(21)
C(22)
C(23)
C(24)
C(11) -0.0131(8)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(19)
C(20)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(27)
C(28)
C(29)
C(30)
C(31)
C(32)
C(33)
C(34)
C(35)
C(36)
C(37)
C(38)
C(39)
C(40)
C(41)
C(42)
C(43)
C(44)
C(45)
O(1)
0.0491(7)
0.1872(6)
0.1607(7)
0.1319(9)
0.133(1)
0.159(1)
0.381(1)
0.1855(9)
0.2244(6)
0.3149(7)
0.2992(8)
0.1962(7)
0.1070(8)
0.1204(7)
0.4174(6)
0.4605(6)
0.4196(7)
0.3353(7)
0.2933(7)
0.3326(6)
0.4606(6)
0.4448(7)
0.4458(9)
0.4656(9)
0.4833(8)
0.4811(7)
0.5918(6)
0.6088(6)
0.7178(8)
0.8026(8)
0.7879(8)
0.6815(7)
0.210(1)
0.4790(9)
0.7089(5)
0.7732(7)
0.8578(8)
0.8802(7)
0.8203(8)
0.7322(7)
0.5312(5)
0.6113(6)
0.6044(7)
0.5194(7)
0.4384(7)
0.4449(6)
0.4248(6)
0.4150(7)
0.3174(9)
0.2325(9)
0.2417(8)
0.3384(7)
0.6374(6)
0.7408(6)
0.8044(7)
0.7696(8)
0.6682(8)
0.6001(7)
0.692(1)
0.1073(6)
0.0760(7)
0.1324(9)
0.1074(8)
0.014(1)
a Ueq ) /3∑i∑jUijai*aj*aiaj.
1
Figure 1. Atomic numbering scheme for (NBu4)[Pt(dtdt)2] (1).
[Ni(dmit)2]3 (5), (SMe3)[Ni(dmit)2]2 (6), and (SMeEt2)[Pd(dmit)2]2 (7)
are summarized in Table 1. All calculations were performed by using
a Gateway 2000 personal computer with the Crystals package.41 Final
atom positional and equivalent thermal parameters are listed in Tables
2-8. Additional relevant parameters of data collections and refinements
and the anisotropic thermal parameters are given in the supplementary
material (Tables S5-S25). The atomic numbering schemes are shown
in Figures 1-5. The atomic scattering factors used were those
calculated by Cromer and Waber.42 The positions of the metal atoms
and most of the sulfur atoms were determined by direct methods using
Shelxs-86.43 The remaining non-hydrogen atoms were located from
subsequent difference Fourier maps. The positions of the hydrogen
0.234(2)
0.807(2)
0.183(1)
0.219(1)
0.656(1)
0.628(1)
0.196(1)
0.3226(9)
a Ueq ) /3∑i∑jUijai*aj*aiaj.
1
atoms were calculated and not refined unless otherwise specified, and
their contribution was included in the calculations by using an isotropic
displacement parameter, B ) 1.3BisoC atom) Å2. Absorption correction
based on DIFABS44 was applied to each data set.
(NBu4)[Pt(dtdt)2] (1). A block-shaped crystal of dimensions 0.2 ×
0.2 × 0.4 mm3 was used. Intensity data (6004 unique reflections with
h ) 0-14, k ) 0-20, l ) -20 to 20) were collected by the ω/1.3θ
scan technique in the θ range 1.5-25°. Reflections (2977) with I >
3σ(I) were used in the calculations. Full matrix least-squares refinement
(41) Watkin, D. J.; Carruthers, J. R.; Betteridge, P. W. CRYSTALS User
guide; Chemical Crystallography Laboratory: University of Oxford,
Oxford, UK, 1985.
(42) Cromer, D. T.; Waber, J. T. International Tables for X-Ray Crystal-
lography; Kynoch Press: Birmingham, England, 1974; Vol. IV, Table
2.2B, p 99.
(43) Sheldrick, G. M. SHELXS86, Program for Crystal Structure Solution;
University of Go¨ttingen: Go¨ttingen, Germany, 1986.
(44) Walker, N.; Stuart, D. Acta Crystallogr. 1983, A39, 158.

3860 Inorganic Chemistry, Vol. 35, No. 13, 1996
Table 4. Atomic Parameters for (SMeEt2)[Ni(dmit)2] (3)
Faulmann et al.
atom
x/a
y/b
z/c
Ueqa (Å2)
Ni(1)
S(1)
S(2)
S(3)
S(4)
S(5)
S(6)
S(7)
S(8)
S(9)
S(10)
S(11)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
0.2576(1)
0.2888(3)
0.2569(2)
0.3057(2)
0.2814(2)
0.3128(3)
0.2368(3)
0.2517(2)
0.2173(3)
0.2280(3)
0.2156(3)
0.2946(2)
0.2760(8)
0.2997(8)
0.2312(8)
0.2370(8)
0.2200(8)
0.100(1)
0.02625(5)
0.1110(1)
0.1081(1)
0.2816(1)
0.2773(1)
0.55522(5)
0.6515(1)
0.4573(1)
0.6387(1)
0.4617(1)
0.5449(1)
0.4574(1)
0.6502(1)
0.4603(1)
0.6373(1)
0.5432(1)
0.2458(1)
0.5114(4)
0.5482(4)
0.5095(4)
0.5936(4)
0.5465(4)
0.2159(6)
0.2352(5)
0.2213(5)
0.2354(6)
0.1635(5)
0.0420
0.0513
0.0488
0.0525
0.0512
0.0657
0.0527
0.0480
0.0524
0.0537
0.0669
0.0530
0.0391
0.0476
0.0433
0.0404
0.0478
0.0710
0.0795
0.0680
0.0732
0.0757
0.4255(1)
-0.0556(1)
-0.0593(1)
-0.2252(1)
-0.2295(1)
-0.3731(1)
0.0104(1)
0.1907(4)
0.3334(4)
-0.1388(4)
-0.1402(4)
-0.2816(4)
-0.0539(4)
-0.1322(5)
0.0985(4)
0.159(1)
0.184(1)
0.317(1)
0.445(1)
0.1630(5)
-0.0024(5)
1
a Ueq ) /3∑i∑jUijai*aj*aiaj.
Table 5. Atomic Parameters for [Pt(dddt)2][Ni(dmit)2]2 (4)
atom
x/a
y/b
z/c
Ueqa (Å2)
Figure 2. Atomic numbering scheme for (a) (PPN)[Ni(dmit)2]‚(CH3)2-
CO (2), (b) (SMeEt)2[Ni(dmit)2] (3), and (c) [Pt(dddt)2][Ni(dmit)2]2 (4).
Pt(1)
Ni(1)
S(1)
S(2)
S(3)
S(4)
S(5)
S(6)
S(7)
S(8)
S(9)
S(10)
S(11)
S(12)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)b
C(9)b
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
-0.2166(4)
-0.2376(4)
0.0000
0.0000
0.0000
0.0000
0.0214
0.0216
0.0354
0.0362
0.0434
0.0469
0.0610
0.0360
0.0351
0.0333
0.0422
0.0517
0.0298
0.0388
0.0294
0.0340
0.0397
0.0309
0.0254
0.0342
0.0219
0.0397
0.0248
0.27953(8)
0.3766(2)
0.2316(2)
0.4219(2)
0.2870(2)
0.3991(3)
0.1828(2)
0.3267(2)
0.1365(2)
0.2713(2)
0.1594(3)
-0.0225(1)
-0.0683(2)
0.3600(8)
0.2957(8)
0.3715(8)
0.1979(8)
0.2640(7)
0.1869(7)
-0.0451(4)
-0.047(1)
-0.087(2)
0.9673(1)
0.9237(3)
0.8244(3)
0.7309(3)
0.6373(3)
0.5221(4)
1.0098(3)
1.1104(3)
1.2036(3)
1.2971(3)
1.4116(3)
0.1053(2)
0.2890(2)
0.805(1)
0.760(1)
0.623(1)
1.126(1)
1.175(1)
1.311(1)
0.1984(6)
0.392(2)
0.385(2)
0.0000
0.0000
0.0000
-0.0981(1)
-0.102(4)
-0.1084(4)
1
a Ueq ) /3∑i∑jUijai*aj*aiaj. b Structure occupation factor, 0.5.
in the space group P21/n with all non-hydrogen atoms anisotropic and
the H atoms of the anion isotropic and refined gave R ) 0.031 and Rw
) 0.035.
Figure 3. Atomic numbering scheme for (BTP)[Ni(dmit)2]3 (5).
(PPN)[Ni(dmit)2]‚(CH3)2CO (2). A black platelet of dimensions
0.38 × 0.18 × 0.05 mm3 was used. Intensity data (5830 unique
reflections with h ) -12 to 12, k ) -14 to 14, l ) 0-16) were
collected by the ω/θ scan technique in the θ range 2.2-22°. Reflections
(3589) with I > 3σ(I) were used in the calculations. All non-hydrogen
atoms, except those belonging to the phenyl groups, were refined
anisotropically in the space group P1h. The final R values were R )
0.057 and Rw ) 0.068.
(SMeEt2)[Ni(dmit)2] (3). A needle-shaped crystal of dimensions
0.09 × 0.23 × 0.40 mm3 was used. Intensity data (3642 unique
reflections with h ) 0-8, k ) 0-21, l ) -19 to 19) were collected
by the ω/2θ scan technique in the θ range 1.5-25°. Reflections (1972)
with I > 3σ(I) were used in the calculations. All non-hydrogen atoms
were refined anisotropically in the space group P21/n. The final R
values were R ) 0.031 and Rw ) 0.033.
Figure 4. Atomic numbering scheme for (SMe3)[Ni(dmit)2]2 (6).
[Pt(dddt)2][Ni(dmit)2]2 (4). A needle-shaped crystal of dimensions
0.10 × 0.15 × 0.37 mm3 was used. Intensity data (1952 unique
reflections with h ) 0-24, k ) 0-8, l ) -16 to 16) were collected
by the ω scan technique in the θ range 2-25°. Reflections (1302)
with I > 3σ(I) were used in the calculations. All non-hydrogen atoms

Metal Complexes of Dithiolate Ligands
Inorganic Chemistry, Vol. 35, No. 13, 1996 3861
Table 6. Atomic Parameters for (BTP)[Ni(dmit)2]3 (5)
atom
x/a
y/b
z/c
Ueqa/Uiso (Å2)
atom
x/a
y/b
z/c
Ueqa/Uiso (Å2)
Ni(1)
Ni(2)
Ni(3)
S(1)
S(2)
S(3)
S(4)
S(5)
S(6)
S(7)
0.70354(7)
0.46091(7)
0.03769(7)
0.6609(2)
0.8353(2)
0.7576(2)
0.9169(2)
0.9165(2)
0.7487(2)
0.5687(2)
0.6454(2)
0.4801(2)
0.4748(3)
0.4185(2)
0.5937(2)
0.5215(2)
0.6880(2)
0.7023(3)
0.5020(2)
0.3325(2)
0.4030(2)
0.2472(2)
0.2430(2)
0.0006(2)
0.1693(2)
0.1039(2)
0.2612(2)
0.2693(2)
0.0789(2)
-0.0952(2)
-0.0217(2)
-0.1909(2)
-0.2018(3)
0.3054(2)
0.7527(6)
0.8297(6)
0.8665(6)
0.6529(6)
0.5730(6)
0.06141(3)
0.94411(3)
0.05518(3)
-0.01084(7)
0.01757(7)
-0.12759(7)
-0.10159(8)
-0.21528(9)
0.13460(8)
0.10414(7)
0.25069(8)
0.22254(8)
0.33656(9)
0.87176(7)
0.90106(7)
0.75570(7)
0.78307(8)
0.67053(9)
0.01749(7)
0.98636(7)
1.13363(7)
1.10430(8)
1.21887(9)
-0.01882(7)
0.01496(7)
-0.13379(7)
-0.10159(7)
-0.21647(9)
0.12814(7)
0.09659(7)
0.2463(8)
0.50133(7)
0.82461(7)
0.17199(7)
0.5635(2)
0.4352(2)
0.5571(2)
0.4342(2)
0.4967(2)
0.4437(2)
0.5659(2)
0.4493(2)
0.5618(2)
0.4969(2)
0.8871(2)
0.7591(2)
0.8865(2)
0.7735(2)
0.8507(3)
0.7644(2)
0.8956(2)
0.7776(2)
0.9014(2)
0.8447(2)
0.2321(2)
0.1029(2)
0.2182(2)
0.0977(2)
0.1505(2)
0.1122(2)
0.2371(2)
0.1219(2)
0.2286(2)
0.1611(3)
0.2016(2)
0.5258(6)
0.4680(6)
0.4962(6)
0.4784(6)
0.5334(6)
0.0304
0.0293
0.0287
0.0361
0.0365
0.0404
0.0399
0.0625
0.0409
0.0378
0.0546
0.0479
0.0712
0.0387
0.0354
0.0462
0.0460
0.0688
0.0355
0.0365
0.0415
0.0397
0.0604
0.0365
0.0349
0.0442
0.0415
0.0627
0.0371
0.0349
0.0495
0.0488
0.0823
0.0466
0.032(2)
0.031(1)
0.040(2)
0.039(2)
0.040(2)
C(6)
C(7)
C(8)
C(9)
0.5301(7)
0.5131(6)
0.5905(6)
0.6419(7)
0.4094(6)
0.3346(6)
0.2950(6)
0.0941(6)
0.1696(6)
0.2144(7)
-0.0151(6)
-0.0939(6)
-0.1412(7)
0.2279(7)
0.1809(9)
0.1184(9)
0.103(1)
0.2732(3)
0.8232(3)
0.8360(3)
0.7329(3)
1.0652(3)
1.0513(3)
1.1560(3)
-0.0656(3)
-0.0500(3)
-0.1550(3)
0.1756(3)
0.1621(3)
0.2648(3)
0.5236(3)
0.4792(4)
0.4457(4)
0.4573(5)
0.5014(5)
0.5349(4)
0.6186(3)
0.6484(4)
0.6897(4)
0.6974(5)
0.6682(5)
0.6277(4)
0.6004(3)
0.6545(3)
0.6775(4)
0.6479(4)
0.5942(4)
0.5700(4)
0.4974(3)
0.5172(4)
0.4857(4)
0.4342(5)
0.4138(5)
0.4451(4)
0.5320(4)
0.5029(7)
0.8526(6)
0.7953(6)
0.8382(&)
0.8043(6)
0.8639(6)
0.8418(6)
0.1918(6)
0.1333(6)
0.1552(7)
0.1503(6)
0.2027(6)
0.1695(7)
0.0840(7)
0.108(1)
0.053(2)
0.035(2)
0.033(2)
0.049(2)
0.034(2)
0.032(2)
0.040(2)
0.038(2)
0.034(2)
0.047(2)
0.039(2)
0.037(2)
0.053(2)
0.050(2)
0.068(3)
0.073(3)
0.082(3)
0.088(3)
0.069(3)
0.046(2)
0.060(2)
0.068(3)
0.079(3)
0.087(3)
0.077(3)
0.044(2)
0.050(2)
0.066(2)
0.073(3)
0.072(3)
0.062(2)
0.052(2)
0.067(2)
0.075(3)
0.082(3)
0.085(3)
0.062(2)
0.055(2)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(19)
C(20)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(27)
C(28)
C(29)
C(30)
C(31)
C(32)
C(33)
C(34)
C(35)
C(36)
C(37)
C(38)
C(39)
C(40)
C(41)
C(42)
C(43)
S(8)
S(9)
S(10)
S(11)
S(12)
S(13)
S(14)
S(15)
S(16)
S(17)
S(18)
S(19)
S(20)
S(21)
S(22)
S(23)
S(24)
S(25)
S(26)
S(27)
S(28)
S(29)
S(30)
P(1)
0.015(1)
-0.097(1)
-0.127(1)
-0.0355(9)
0.2324(7)
0.1380(9)
0.162(1)
0.275(1)
0.370(1)
0.347(1)
0.1561(7)
0.1834(7)
0.1532(9)
0.1004(9)
0.0699(9)
0.1011(8)
0.3363(7)
0.3788(9)
0.378(1)
0.335(1)
0.292(1)
0.2935(8)
0.3381(8)
0.144(1)
0.2087(9)
0.1980(7)
0.1174(8)
0.0344(9)
0.035(1)
0.114(1)
0.197(1)
0.4100(7)
0.4242(7)
0.5119(8)
0.5834(9)
0.5675(9)
0.4822(8)
0.4956(7)
0.6053(9)
0.707(1)
0.21405(8)
0.3269(1)
0.56879(8)
-0.0602(3)
-0.0478(2)
-0.1517(3)
0.1829(3)
C(1)
C(2)
C(3)
C(4)
0.700(1)
0.592(1)
0.4883(9)
0.3841(8)
C(5)
0.1698(3)
1
a Ueq ) /3∑i∑jUijai*aj*aiaj.
refined anisotropically in the space group P1h. The final R values were
R ) 0.075 and Rw ) 0.084.
(SMeEt2)[Pd(dmit)2]2 (7). A plate-shaped crystal of dimensions
0.40 × 0.30 × 0.05 mm3 was used. Cell parameters were obtained by
least-squares refinements on the basis of the setting angles of 15
reflections. Intensity data (4304 unique reflections with h ) -8 to 8,
k ) -38 to 38, l ) 0-6) were collected by the ω/θ scan technique in
the θ range 1.5-22.5°. Reflections (3049) with I > 3σ(I) were used
in the calculations. All non-hydrogen atoms were refined anisotropi-
cally in the space group P1h. The final R values were R ) 0.074 and
Rw ) 0.093.
Conductivity Measurements. Ambient pressure, room temperature
compacted powder conductivity was measured on compressed pellets
by using a Hewlett-Packard Model 4263A LCR meter. Temperature
dependent (300-4 K) single-crystal conductivity measurements were
carried out following the standard four-probe technique. Electrical
contacts were obtained by gluing four gold wires to the crystal with
Emetron M8001 gold paint. The sample mounted on a Motorola printed
circuit was placed in an Oxford Instruments Model CF 200 continuous
flow cryostat. Monitoring of the temperature variations and temperature
resistance data acquisition was achieved by using an Oxford Instruments
Model DTC2 PID temperature controller and the above-cited Hewlett-
Packard device, both driven by a PC with homemade software.
Figure 5. Atomic numbering scheme for (SMeEt2)[Pd(dmit)2]2 (7).
were refined anisotropically in the space group C2/m. The final R
values were R ) 0.047 and Rw ) 0.049.
(BTP)[Ni(dmit)2]3 (5). A black bar-shaped crystal of dimensions
0.63 × 0.15 x 0.08 mm3 was used. Cell parameters were obtained by
least-squares refinements on the basis of the setting angles of 22
reflections. Intensity data (8997 unique reflections with h ) -13 to
13, k ) -27 to 27, l ) 0-13) were collected by the ω/θ scan technique
in the θ range 1.5-23°. Reflections (4965) with I > 3σ(I) were used
in the calculations. All atoms except those belonging to phenyl groups
(including H atoms) were refined anisotropically in the space group
P1h. The final R values were R ) 0.049 and Rw ) 0.051.
(SMe3)[Ni(dmit)2]2 (6). A plate-shaped crystal of dimensions 0.24
× 0.30 × 0.9 mm3 was used. Intensity data (5502 unique reflections
with h ) 0-9, k ) -13 to 13, l ) -21 to 21) were collected by the
ω/2θ scan technique in the θ range 1.5-20°. Reflections (3147) with
I > 3σ(I) were used in the calculations. All non-hydrogen atoms were
Band Structure Calculations. The tight-binding band structure
calculations are based upon the effective one-electron Hamiltonian of
the extended Hu¨ckel method.45 The off-diagonal matrix elements of
the Hamiltonian were calculated according to the modified Wolfsberg-
(45) Hoffmann, R. J. Chem. Phys. 1963, 39, 1397. Whangbo, M.-H.;
Hoffmann, R. J. Am. Chem. Soc. 1978, 100, 6093.

3862 Inorganic Chemistry, Vol. 35, No. 13, 1996
Table 7. Atomic Parameters for (SMe3)[Ni(dmit)2]2 (6)
Faulmann et al.
Table 8. Atomic Parameters for (SMeEt2)[Pd(dmit)2]2 (7)
atom
x/a
y/b
z/c
Ueqa (Å2)
atom
x/a
y/b
z/c
Ueqa (Å2)
Ni(1)
S(1)
S(2)
S(3)
S(4)
S(5)
S(6)
S(7)
S(8)
S(9)
S(10)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
Ni(1)
S(11)
S(12)
S(13)
S(14)
S(15)
S(16)
S(17)
S(18)
S(19)
S(20)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
S(21)
C(210)
C(211)
C(212)
0.4325(1)
0.4007(2)
0.3408(2)
0.2760(2)
0.2197(2)
0.1515(3)
0.4692(2)
0.5086(2)
0.5853(2)
0.6186(3)
0.6915(3)
0.3257(8)
0.2949(8)
0.2137(9)
0.5375(8)
0.5531(8)
0.6355(9)
0.8449(1)
0.8195(2)
0.7665(2)
0.7063(3)
0.6571(3)
0.5960(4)
0.8752(2)
0.9321(2)
1.0093(2)
1.0620(2)
1.1487(3)
0.7516(8)
0.7265(8)
0.653(1)
0.22192(7)
0.3842(1)
0.1212(1)
0.4366(1)
0.1922(1)
0.3647(2)
0.0571(1)
0.3251(1)
0.0049(2)
0.2517(2)
0.0770(2)
0.3408(5)
0.2242(5)
0.3323(6)
0.1018(6)
0.2196(6)
0.1085(6)
0.25935(6)
0.4249(1)
0.1604(1)
0.4838(1)
0.2410(2)
0.4213(2)
0.0933(1)
0.3565(1)
0.0306(1)
0.2734(2)
0.0864(2)
0.3838(5)
0.2695(5)
0.3843(6)
0.1324(5)
0.2474(5)
0.1295(6)
0.3257(2)
0.3495(8)
0.1905(7)
0.2762(9)
0.57267(5)
0.4857(1)
0.4994(1)
0.3235(1)
0.3369(1)
0.1894(1)
0.6583(1)
0.6492(1)
0.8224(1)
0.8144(1)
0.9614(1)
0.4107(4)
0.4178(4)
0.2794(4)
0.7344(4)
0.7301(4)
0.8707(4)
0.47698(5)
0.3930(1)
0.3987(1)
0.2285(1)
0.2337(1)
0.0878(1)
0.5608(1)
0.5544(1)
0.7210(1)
0.7155(1)
0.8566(1)
0.3152(4)
0.3177(4)
0.1791(4)
0.6364(4)
0.6333(4)
0.7693(4)
1.0191(1)
0.9307(6)
1.0701(5)
0.9942(6)
0.0268
0.0338
0.0337
0.0347
0.0346
0.0509
0.0349
0.0311
0.0385
0.0419
0.0506
0.0246
0.0182
0.0347
0.0255
0.0283
0.0354
0.0255
0.0328
0.0300
0.0357
0.0382
0.0554
0.0331
0.0339
0.0340
0.0352
0.0446
0.0236
0.0210
0.0379
0.021
Pd(1)
Pd(2)
S(1)
0.1881(1)
0.1852(1)
0.451(1)
0.48158(3)
0.01891(3)
0.2523(2)
0.4342(1)
0.44734(9)
0.3591(1)
0.3702(1)
0.2983(1)
0.5263(1)
0.51507(9)
0.5979(1)
0.5879(1)
0.6565(1)
-0.01456(9)
-0.0258(1)
-0.0872(1)
-0.0972(1)
-0.1561(1)
0.0533(1)
0.0658(1)
0.1306(1)
0.1413(1)
0.2025(1)
0.222(2)
1.0179(2)
1.0217(2)
0.768(1)
0.7698(6)
1.3231(6)
0.8591(7)
1.3493(6)
1.1519(9)
1.2695(6)
0.7176(6)
1.1966(6)
0.7064(6)
0.9138(9)
0.7111(6)
1.2606(6)
0.6774(6)
1.1673(6)
0.8650(8)
1.3354(6)
0.7860(6)
1.3801(7)
0.8919(7)
1.201(1)
0.597(5)
0.563(5)
0.502(6)
0.731(4)
0.872(6)
0.954(2)
1.192(2)
1.123(3)
1.095(2)
0.859(2)
0.941(3)
0.844(2)
1.073(2)
0.905(2)
1.215(2)
0.983(2)
1.157(3)
0.0295
0.0289
0.1008
0.0354
0.0349
0.0441
0.0415
0.0620
0.0369
0.0358
0.0422
0.0415
0.0539
0.0341
0.0354
0.0395
0.0391
0.0544
0.0357
0.0357
0.0434
0.0475
0.0684
0.0692
0.1160
0.1464
0.1011
0.1491
0.0206
0.0259
0.0463
0.0282
0.0332
0.0420
0.0350
0.0319
0.0355
0.0249
0.0300
0.0456
S(11)
S(12)
S(13)
S(14)
S(15)
S(16)
S(17)
S(18)
S(19)
S(20)
S(21)
S(22)
S(23)
S(24)
S(25)
S(26)
S(27)
S(28)
S(29)
S(30)
C(1)
0.0366(5)
0.1982(5)
-0.0655(6)
0.0798(6)
-0.0900(8)
0.3559(5)
0.1962(5)
0.5048(6)
0.3647(6)
0.5609(7)
0.1965(5)
0.3593(5)
0.3714(6)
0.5155(5)
0.5766(7)
0.1901(5)
0.0284(5)
0.0602(6)
-0.0849(6)
-0.1161(8)
0.402(5)
0.475(4)
0.648(5)
0.213(4)
0.162(5)
0.028(2)
0.099(2)
-0.028(2)
0.387(2)
0.316(2)
0.480(2)
0.325(2)
0.390(2)
0.487(2)
0.086(2)
0.017(2)
-0.054(2)
C(2)
C(3)
C(4)
C(5)
0.283(1)
0.270(1)
0.2626(8)
0.236(1)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
0.4022(4)
0.4071(3)
0.3400(4)
0.5577(4)
0.5526(4)
0.6169(4)
-0.0519(4)
-0.0570(4)
-0.1163(4)
0.0934(4)
0.0984(4)
0.1602(5)
0.9529(8)
0.9779(8)
0.10758(9)
0.0587(4)
-0.045(2)
-0.011(1)
0.273(1)
0.0226
0.0323
0.0527
0.0764
0.0551
0.0685
a Ueq ) /3∑i∑jUijai*aj*aiaj.
1
Hemholz formula.46 All valence electrons were explicitly taken into
account in the calculations. The basis set consisted of Slater type
orbitals of double-ú quality for Pd 4d and single-ú quality for Pd 5s
and 5p, S 3s and 3p, and C 2s and 2p. The exponents, contraction
coefficients of the double-ú orbitals, and atomic parameters used for
the calculations were taken from previous work.47
1
a Ueq ) /3∑i∑jUijai*aj*aiaj.
Scheme 1
Results and Discussion
Synthesis and Crystal Structure of [ML2]n- Complexes
(L ) dmit2-, dddt2-, and dtdt2-; n ) 2 or 1). Both the dddt2-
and dtdt2- ligands have been obtained as their potassium salts
by hydrolysis of the appropriate thione, C5H4S5 and C5H4S6,
respectively (Scheme 1). It is interesting to note that both of
these thiones are obtained from dmit-based compounds, e.g.,
dmitNa2 or (NR4)2[Zn(dmit)2], respectively, by ring closure with
dibromoethane or dichloromethyl sulfide, respectively.
The (cation)n[ML2] complexes (L ) dmit2-, dddt2-, and
dtdt2-) are obtained by complexation of the ligand L with an
appropriate metal salt and precipitation with a salt of the
appropriate cation. Whereas in the case of the dmit2- ligand
the expected divalent [cation)2[M(dmit)2] complexes (cation )
NR4+, PPN+, BTP+, (SMeyEt3-y)+] are readily obtained, in the
case of both the dddt2- and dtdt2- ligands, the monovalent
(NR4)[ML2] complexes are directly obtained, even under a
nonoxidating atmosphere. Facile oxidation of the (NR4)-
[M(dddt)2] complexes affording the neutral [M(dddt)2]0 species
is observed, whereas only one neutral dmit-based complex,
namely, [Ni(dmit)2]0, has been obtained as a minority product
in the preparation of the charge transfer salt (TTF)[Ni-
(dmit)2]2.26b Oxidation of the (NR4)[M(dtdt)2] complexes, af-
fording the neutral [M(dtdt)2]0 species, is also possible (Vide
infra).
(46) Ammeter, J.; Bu¨rgi, H.-B.; Thibeault , J.; Hoffmann, R. J. Am. Chem.
Soc. 1978, 100, 3686.
(47) Canadell E.; Rachidi E.-I.; Ravy S.; Pouget J.-P.; Brossard L.; Legros
J.-P. J. Phys. Fr. 1989, 50, 2967.

Metal Complexes of Dithiolate Ligands
Inorganic Chemistry, Vol. 35, No. 13, 1996 3863
Table 9. Selected Bond Distances and Angles (deg) for (NBu4)[Pt(dtdt)2] (1)
Pt(1)-S(1)
Pt(1)-S(2)
Pt(1)-S(6)
Pt(1)-S(7)
S(1)-C(1)
S(2)-C(2)
2.261(3)
2.259(3)
2.268(3)
2.255(3)
1.71(1)
S(3)-C(1)
S(3)-C(3)
S(4)-C(2)
S(4)-C(4)
S(5)-C(3)
S(5)-C(4)
1.75(1)
1.81(1)
1.76(1)
1.80(1)
1.78(1)
1.79(1)
S(6)-C(6)
S(7)-C(5)
S(8)-C(6)
S(8)-C(8)
S(9)-C(5)
S(9)-C(7)
1.73(1)
1.72(1)
1.75(1)
1.81(1)
1.77(1)
1.80(1)
S(10)-C(7)
S(10)-C(8)
C(1)-C(2)
C(5)-C(6)
1.79(1)
1.78(1)
1.38(1)
1.36(1)
1.71(1)
S(1)-Pt(1)-S(2)
S(1)-Pt(1)-S(6)
S(2)-Pt(1)-S(6)
S(1)-Pt(1)-S(7)
S(2)-Pt(1)-S(7)
S(6)-Pt(1)-S(7)
Pt(1)-S(1)-C(1)
Pt(1)-S(2)-C(2)
C(1)-S(3)-C(3)
C(2)-S(4)-C(4)
C(3)-S(5)-C(4)
88.5(1)
175.2(1)
92.07(9)
90.7(1)
179.2(1)
88.7(1)
104.5(4)
104.6(3)
103.5(4)
102.8(5)
100.1(5)
Pt(1)-S(6)-C(6)
Pt(1)-S(7)-C(5)
C(6)-S(8)-C(8)
C(5)-S(9)-C(7)
C(7)-S(10)-C(8)
S(1)-C(1)-S(3)
S(1)-C(1)-C(2)
S(3)-C(1)-C(2)
S(2)-C(2)-S(4)
S(2)-C(2)-C(1)
S(4)-C(2)-C(1)
104.0(4)
S(3)-C(3)-S(5)
117.3(6)
118.0(6)
113.3(6)
122.4(8)
124.2(8)
115.7(6)
120.6(8)
123.6(8)
117.7(7)
117.0(6)
103.8(4)
103.8(5)
101.3(6)
101.8(5)
114.9(6)
121.3(8)
123.8(8)
115.1(6)
121.1(8)
123.8(8)
S(4)-C(4)-S(5)
S(7)-C(5)-S(9)
S(7)-C(5)-C(6)
S(9)-C(5)-C(6)
S(6)-C(6)-S(8)
S(6)-C(6)-C(5)
S(8)-C(6)-C(5)
S(9)-C(7)-S(10)
S(8)-C(8)-S(10)
Table 10. Selected Bond Distances and Angles (deg) for (PPN)[Ni(dmit)2]‚(CH3)2CO (2)
Ni(1)-S(1)
S(1)-C(1)
S(4)-C(2)
S(7)-C(5)
S(9)-C(6)
P(1)-C(7)
P(2)-C(31)
2.165(2)
1.711(8)
1.742(8)
1.699(8)
1.72(1)
1.799(7)
1.803(8)
Ni(1)-S(2)
S(2)-C(2)
S(4)-C(3)
S(8)-C(4)
S(10)-C(6)
P(1)-C(13)
P(2)-C(37)
2.160(2)
1.714(8)
1.723(8)
1.740(8)
1.640(9)
1.795(8)
1.789(8)
Ni(1)-S(6)
S(3)-C(1)
S(5)-C(3)
S(8)-C(6)
N(1)-P(1)
P(1)-C(19)
C(1)-C(2)
2.161(2)
Ni(1)-S(7)
S(3)-C(3)
S(6)-C(4)
S(9)-C(5)
N(1)-P(2)
P(2)-C(25)
C(4)-C(5)
2.167(2)
1.746(9)
1.722(8)
1.740(8)
1.594(6)
1.796(7)
1.37(1)
1.738(8)
1.636(8)
1.736(9)
1.567(6)
1.792(7)
1.36(1)
S(1)-Ni(1)-S(2)
Ni(1)-S(2)-C(2)
Ni(1)-S(6)-C(4)
C(5)-S(9)-C(6)
N(1)-P(1)-C(13)
C(7)-P(1)-C(19)
N(1)-P(2)-C(31)
C(25)-P(2)-C(37)
S(3)-C(1)-C(2)
S(3)-C(3)-S(4)
S(6)-C(4)-C(5)
S(9)-C(5)-C(4)
S(9)-C(6)-S(10)
92.83(8)
S(6)-Ni(1)-S(7)
C(1)-S(3)-C(3)
Ni(1)-S(7)-C(5)
P(1)-N(1)-P(2)
C(7)-P(1)-C(13)
C(13)-P(1)-C(19)
C(25)-P(2)-C(31)
C(31)-P(2)-C(37)
S(2)-C(2)-C(1)
S(3)-C(3)-S(5)
S(8)-C(4)-C(5)
S(8)-C(6)-S(9)
93.11(9)
Ni(1)-S(1)-C(1)
102.5(3)
97.7(4)
97.0(4)
103.3(3)
102.3(3)
98.4(4)
97.4(4)
102.2(3)
137.9(4)
108.9(3)
107.3(3)
108.4(3)
107.7(3)
121.5(6)
123.3(5)
116.9(6)
113.0(5)
C(2)-S(4)-C(3)
C(4)-S(8)-C(6)
N(1)-P(1)-C(7)
N(1)-P(1)-C(19)
N(1)-P(2)-C(25)
N(1)-P(2)-C(37)
S(1)-C(1)-C(2)
S(4)-C(2)-C(1)
S(4)-C(3)-S(5)
S(7)-C(5)-C(4)
S(8)-C(6)-S(10)
114.2(3)
107.1(3)
112.8(3)
107.8(3)
120.8(6)
116.0(6)
124.0(5)
122.0(6)
123.4(6)
112.5(3)
106.5(3)
112.8(3)
107.2(3)
116.1(6)
112.8(5)
120.5(6)
114.7(6)
123.6(6)
of the M-S distances, the intramolecular distances in the
[Pt(dtdt)2]- anion are almost similar to those found in (NBu4)-
[Ni(dtdt)2].29
(PPN)[Ni(dmit)2]‚(CH3)2CO (2). Selected bond lengths and
angles are listed in Table 10. The averaged intramolecular
distances and angles within the [Ni(dmit)2] unit are in agreement
with those found for (NBu4)[Ni(dmit)2].48,50 The unit cell
contains two [Ni(dmit)2]- units, two PPN+ cations and two
acetone molecules. The structure consists of layers of [Ni-
(dmit)2] units lying side by side (Figure 7a). These layers,
separated by sheets of cations and solvent molecules, are built
of infinite chains of Ni(dmit)2 entities connected to each other
by short S‚‚‚S contacts and running along [100] (Figure 7b).
No short S‚‚‚S contacts are observed between the chains. The
distances within the PPN+ cation are similar to those found in
other PPN+ salts.51 The PPN+ cation adopts a bent structure
[angle P-N-P ) 137.9(4)°], which is the usual geometry for
the PPN+ cation.51
Figure 6. Side view of the [Pt(dtdt)2]- anion in (NBu4)[Pd(dtdt)2] (1).
All prepared [ML2]n- complexes (L ) dmit2-, dddt2-, and
dtdt2-; n ) 2, 1, or 0) have been characterized by elemental
analysis and infrared spectroscopy. Further characterization is
provided by the determination of the crystal structures of
(NBu4)[Pt(dtdt)2] (1), (PPN)[Ni(dmit)2]‚(CH3)2CO (2), and
(SMeEt2)[Ni(dmit)2] (3).
(NBu4)[Pt(dtdt)2] (1). Selected bond lengths and angles are
listed in Table 9. A side view of the [Pt(dtdt)2]- anion is shown
in Figure 6. The anion adopts a chair conformation: the central
part is almost planar (largest deviation ) (0.27 Å, dihedral
angle between the two PtC2S4 moieties ) 9.25°), and the two
external C2S planes lie above and below this plane at a distance
of ≈1.6 Å. This structure is very similar to that of the analogue
(NBu4)[Ni(dtdt)2] complex.29 The averaged Pt-S distances in
1 (2.261 Å) are comparable to those found for other monovalent
1,2-dithiolate platinum complexes, such as (NBu4)[Pt(dmit)2]
(2.28 Å)48 or (NEt4)[Pt(dddt)2] (2.27 Å).49 With the exception
(SMeEt2)[Ni(dmit)2] (3). Selected bond lengths and angles
are listed in Table 11. The averaged intramolecular distances
and angles within the [Ni(dmit)2] unit are in agreement with
those found for (PPN)[Ni(dmit)2]‚(CH3)2CO (2) and (NBu4)-
[Ni(dmit)2].48,50 The projection of the structure onto the bc plane
is shown in Figure 8a. The structure consists of [Ni(dmit)2]
(49) Welch, J. H.; Bereman, R. D.; Singh, P. Inorg. Chim. Acta 1989, 163,
93-98.
(50) Lindqvist, O.; Andersen, L.; Sieler, J .; Steimecke, G; Hoyer, E. Acta
Chem. Scand. 1982, A36, 855.
(48) (a) Mentzafos, D.; Hountas, A. Acta Crystallogr. 1988, C44, 1550.
(b) Baumer, V. N.; Starodub, V. A.; Tarasova, G. E. SoV. Phys.
Crystallogr. 1989, 34, 59.
(51) Wilson, R. D.; Bau, R. J. Am. Chem. Soc. 1974, 96, 7601

3864 Inorganic Chemistry, Vol. 35, No. 13, 1996
Faulmann et al.
Figure 7. (PPN)[Ni(dmit)2]‚(CH3)2CO (2): (a) projection along the long axis of the Ni(dmit)2 units [for clarity, only the Ni(dmit)2, C-CO-C, and
P-N-P moieties are represented; dotted lines represent the S‚‚‚S distances shorter than the sum of the van der Waals radii (3.7 Å)]; (b) projection
perpendicular to the plane of the Ni(dmit)2 units.
Table 11. Selected Bond Distances and Angles (deg) for (SMeEt2)[Ni(dmit)2] (3)
Ni(1)-S(1)
Ni(1)-S(2)
Ni(1)-S(6)
Ni(1)-S(7)
S(1)-C(1)
2.173(2)
2.157(2)
2.153(2)
2.171(2)
1.715(7)
S(2)-C(2)
S(3)-C(1)
S(3)-C(3)
S(4)-C(2)
S(4)-C(3)
1.715(6)
1.739(7)
1.734(7)
1.741(6)
1.721(7)
S(5)-C(3)
S(6)-C(4)
S(7)-C(5)
S(8)-C(4)
S(8)-C(6)
1.643(7)
1.707(7)
1.709(6)
1.734(7)
1.721(7)
S(9)-C(5)
S(9)-C(6)
S(10)-C(6)
C(1)-C(2)
C(4)-C(5)
1.744(6)
1.740(7)
1.631(7)
1.356(8)
1.363(8)
Ni(1)-S(1)-C(1)
Ni(1)-S(2)-C(2)
Ni(1)-S(6)-C(4)
Ni(1)-S(7)-C(5)
S(1)-Ni(1)-S(2)
S(1)-C(1)-C(2)
S(2)-C(2)-C(1)
S(3)-C(1)-C(2)
101.9(2)
S(3)-C(3)-S(4)
S(3)-C(3)-S(5)
S(4)-C(2)-C(1)
S(4)-C(3)-S(5)
S(6)-C(4)-C(5)
S(6)-Ni(1)-S(7)
S(7)-C(5)-C(4)
S(8)-C(4)-C(5)
112.294)
S(8)-C(6)-S(9)
112.1(4)
123.9(4)
115.2(5)
124.0(4)
98.3(3)
98.0(3)
98.4(3)
98.1(3)
101.9(2)
102.9(2)
102.2(2)
93.24(7)
121.0(5)
122.0(5)
115.2(5)
124.1(4)
116.3(5)
123.6(4)
120.9(5)
92.67(7)
121.3(5)
116.2(5)
S(8)-C(6)-S(10)
S(9)-C(5)-C(4)
S(9)-C(6)-S(10)
C(1)-S(3)-C(3)
C(2)-S(4)-C(3)
C(4)-S(8)-C(6)
C(5)-S(9)-C(6)
units parallel to the bc plane and connected to each other through
short S‚‚‚S (<3.70 Å) contacts, via either the cation (SMeEt2)+
or their own sulfur atoms. The Ni(dmit)2 entities form zig-zag
stacks along the [100] direction (Figure 8b).
Compared Electrochemical Behavior of the [ML2]n-
Complexes Studied (L ) dmit2-, dtdt2-, and dddt2-). The
electrochemical behavior of (NR4)[Ni(dmit)2] complexes has
been previously studied in detail.38 From these studies, the

Metal Complexes of Dithiolate Ligands
Inorganic Chemistry, Vol. 35, No. 13, 1996 3865
Figure 8. (a) Projection of (SMeEt2)[Ni(dmit)2] (3) onto the bc plane. (b) Side view of the along the [100] direction.
(dmit)2]0. (3) The NIOS radical anion {[Ni(dmit)2]x-
}
is
n+m
formed by a chemical reaction, in the diffusion layer, between
[Ni(dmit)2]- and [Ni(dmit)2]0 species. This compound, being
insoluble, is deposited on the anode.
In the present work, the (cation)[M(dmit)2] complexes studied
+
with M ) Ni, Pt and cation ) PPN+, BTP+, and (SMeyEt3-y
)
and the (cation)[Pd(dmit)2] complexes with cation ) PPN+,
BTP+ exhibit similar electrochemical behavior (Figure 9a, and
Figure S1 and Table S26 in the supplementary material), and
the same mechanism can be applied to the formation of their
derived NIOS compounds. In the cyclic voltammogram of the
(SMeyEt3-y)2[Pd(dmit)2] complexes, only one, instead of two,
redox wave is observed (Figure 9b and Figure S1 and Table
S26 in the supplementary material), indicating that reactions
1-3 take place simultaneously at the same potential. This
explains why the monovalent (SMeyEt3-y)[Pd(dmit)2] complexes
could not be obtained by iodine oxidation of the corresponding
divalent (SMeyEt3-y)2[Pd(dmit)2] complexes (see the Experi-
mental Section).
The electrochemical behavior of (NR4)[M(dddt)2] complexes
(M ) Ni, Pt) has also been previously described and discussed39
and is quite different from that of the (cation)[M(dmit)2]
complexes. From these studies, the following mechanism has
been proposed:
[M(dddt)2]2- / [M(dddt)2]-
[M(dddt)2]- a [M(dddt)2]0
(1′)
(2′)
(3′)
(4′)
(5′)
Figure 9. Cyclic voltammograms of (a) (SMe3)[Ni(dmit)2] (10-3 M)
and (b) (SMe3)[Pd(dmit)2] (10-3 M), in CH3CN/(SMe3)BF4 (10-1 M)
at a Pt electrode (1 mm) with a scan rate of 0.1 V s-1 [potential in
volts Vs Ag/AgCl (* starting potential)].
n[M(dddt)2]- + m[M(dddt)2]0 f {[M(dddt)2]x-}n+m
[M(dddt)2]0 / [M(dddt)2]+
following mechanism for the formation of the derived (NR4)-
[Ni(dmit)2]z NIOS complexes has been proposed:
[Ni(dmit)2]2- / [Ni(dmit)2]-
[Ni(dmit)2]- a [Ni(dmit)2]0
(1)
(2)
p[M(dddt)2]0 + q[M(dddt)2]+ f {[M(dddt)2]x+}p+q
where x ) q/(p + q).
n[Ni(dmit)2]- + m[Ni(dmit)2]0 f {[Ni(dmit)2]x-}n+m (3)
[Ni(dddt)2]+ - (oxidation-decomposition) f
organic radicals (6′)
where x ) 1/z ) n/(n + m). (1) The first one-electron transfer,
which appears quasi-reversible at any potential scan rate,
corresponds to the [Ni(dmit)2]2-/[Ni(dmit)2]- couple. (2) The
second electron transfer, which appears quasi-reversible only
at fast potential scan rates, generates the neutral species [Ni-
(1′-3′) The first two oxidation waves observed, which are quasi-
reversible even at low scan rate, correspond to the [M(dddt)2]2-
/
[M(dddt)2]- and [M(dddt)2]-/[M(dddt)2]0 couples. In the
present case, reaction 3′, which could have been expected

3866 Inorganic Chemistry, Vol. 35, No. 13, 1996
Faulmann et al.
ary conditions (Figure 11c), the reversibility was established
for both waves by standard tests (Nernstian shape, diffusion-
controlled process, peak intensity),56 and coulometry experi-
ments show that one electron is accounted for both transfers.
Finally, in benzonitrile the second wave is quasi-reversible, even
at low scan rate, and no typical features that could be associated
with the deposition of a conductive species are observed (Figure
11d).
Still, the typical features associated with the deposition of a
conductive species on the anode observed in acetonitrile remain
to be explained. Galvanostatic electrocrystallization of aceto-
nitrile solutions of (NR4)[M(dtdt)2] (M ) Ni, Pt) yields shiny
needle-shaped crystals.31 These samples exhibit poor powder
conductivities (10-7 and 10-3 S cm-1, respectively), and the
elemental analyses were compatible with the formulas for the
corresponding neutral [M(dtdt)2]0 species.
Figure 10. Cyclic voltammogram of (NEt4)[Pd(dddt)2] (10-3 M) in
acetone/(NEt4)BF4 (10-1 M) at a Pt electrode (1 mm) with a scan rate
of 0.1 V s-1 [potential in volts Vs Ag/AgCl (* starting potential)].
between the [M(dddt)2]- and [M(dddt)2]0 species, does not seem
to take place. (4′) A third electron transfer, which appears quasi-
reversible only at fast potential scan rates, generates the
[M(dddt)2]+ cation. (5′) The formation of the {[M(dddt)2]x+}p+q
radical cation, from which several examples of salts have been
reported,52-55 results from the reaction between the [M(dddt)2]0
and [M(dddt)2]+ species. (6′) In the case of the nickel
compounds, oxidation-decomposition processes make the
mechanism more complicated and explain the irreversibility of
the third wave.39
In conclusion, oxidation of the [M(dtdt)2]- complexes in
acetonitrile as well as in benzonitrile, and at any potential scan
rate, yields the neutral [M(dtdt)2]0 species instead of the
{[M(dtdt)2]x-
}n+m NIOS radical anion, and the reaction of type
3 between the monoanion and the neutral species, observed in
the case of the [M(dmit)2] complexes, does not take place in
the case of the [M(dtdt)2] complexes. Whereas [M(dtdt)2]0 is
soluble in benzonitrile, it is insoluble in acetonitrile and is
deposited on the anode. However, its conductivity is sufficiently
high to not passivate the electrode.
The previous studies on nickel and platinum (NR4)[M(dddt)2]
complexes39 have been extended to the palladium analogue
complex. The behavior of (NEt4)[Pd(dddt)2] (Figure 10 and
Figure S1 and Table S26 in the supplementary material) is quite
similar to that of the platinum analogue complex and confirms
the proposed mechanism. Thus, the [M(dddt)2] complexes may
be readily used for the preparation of NIOS radical cation
salts.52-55 Moreover, the [M(dddt)2] complexes may also be
used as donor molecules in the preparation of [M(dddt)2][M′-
(dmit)2]x compounds (Vide infra). By contrast, as reaction 3′
does not seem to take place, the preparation of (cation)-
[M(dddt)2]z NIOS radical anion salts should not be possible.
In the case of the (NR4)[M(dtdt)2] complexes, the cyclic
voltammetry data were deceiving at first sight. The cyclic
voltammogram of these complexes in acetonitrile (Figure 11
and Figure S1 and Table S27 in the supplementary material)
looks quite similar to those of the (NR4)[M(dmit)2] complexes38
and consists of two waves, a first quasi-reversible one corre-
sponding to the [M(dtdt)2]2-/[M(dtdt)2]- couple and a second
one exhibiting the typical features associated with the deposition
of a conductive species on the anode:38 a fast increase in the
current of the anodic peak, the presence of an intense backward
peak characteristic of a redissolution process, the observation
of a black deposit on the anode, and an increase in the peak’s
intensity on a subsequent potential scan to more anodic
potentials. When the potential scan rate is increased, the
intensity of the redissolution peak decreases. At 800 V s-1 for
the nickel compound and 300 V s-1 for the platinum compound,
the electron transfer becomes reversible and generates the neutral
[M(dtdt)2]0 species (Figure 11b). From these results, it could
[M(dddt)2][M′(dmit)2]x Compounds. As discussed earlier,
the [M(dddt)2] complexes may be used for the preparation of
NIOS radical cation salts, such as [Ni(dddt)2]3X2 with X )
- 52
- 53
- 54
-
BF4
,
HSO4
,
AuBr2
,
[Pt(dddt)2]2X with X ) IBr2 ,
ICl2-, AuBr2
,
- 55 and [Pd(dddt)2]2X with X ) AgxBry-, AuBr2
,
-
- 54
PF6
.
We have prepared bimetallic compounds [M(dddt)2]-
[M′(dmit)2]x (M, M′ ) Ni, Ni; Ni, Pd; Pt, Ni; Pt, Pd), in which
[M(dddt)2] and [M′(dmit)2] play the roles of a donor cation and
an acceptor anion, respectively (see the Experimental Section).
Crystalline samples have been obtained in all cases, and their
powder conductivity is rather modest (10-3-10-5 S cm-1). Their
stoichiometry could not be inferred with certainty from just
elemental analyses. In one case (M, M′ ) Pt, Ni), the crystal
quality allowed an X-ray structural study, from which a 1/2
stoichiometry has been determined.
Selected bond lengths and angles for [Pt(dddt)2][Ni(dmit)2]2
(4) are listed in Table 12. No significant differences can be
observed between the intramolecular distances in the Pt(dddt)2
entity and the distances observed for the neutral Pt(dddt)2
compound.35 On the contrary, if most of the distances within
the Ni(dmit)2 unit are similar to those found for the [Ni(dmit)2]n-
complexes, the averaged Ni-S and S-C distances (2.134 and
1.67 Å, respectively) are even shorter than those observed for
the neutral Ni(dmit)2 compound (2.147 and 1.699 Å).26b This
may indicate that the delocalization is very important in the
central rings of the Ni(dmit)2 unit, following the model proposed
by Schrauzer.57 The structure consists of stacks along [010] of
Ni(dmit)2 planar entities perpendicular to Pt(dddt)2 entities,
which are also planar with the exception of their terminal CH2-
CH2 groups (Figure 12a). The Ni(dmit)2 stacks are separated
by layers of the Pt(dddt)2 entities lying side by side. Short S‚‚‚S
contacts only exist between the Ni(dmit)2 and Pt(dddt)2 units
but not within the Ni(dmit)2 stacks, although the interplanar
distance is 3.60 Å (Figure 12b). In spite of a promising
stoichiometry, which could involve a partial oxidation state for
either the [Pt(dddt)2] and/or the [Ni(dmit)2] components (unless
the charge transfer is zero), this type of structural arrangement
be inferred that the {[M(dtdt)2]x-
}
radical anion could be
n+m
generated by electrocrystallization.29 Conversely, under station-
(52) Yagubskii, E. B.; Kotov, A. I.; Buravov, L. I.; Khomenko, A. G.;
Shklover, B. E.; Nahapetyan, S. S.; Struchkov, Yu. T.; Vetoshkina,
L. V.; Ukhin, L. Yu. Synth. Metals 1990, 35, 271.
(53) Yagubskii, E. B.; Kotov, A. I.; Khomenko, A. G.; Buravov, L. I.;
Schegolev, V. E.; Shibaeva, R. P. Synth. Metals 1991, 46, 255.
(54) Yagubskii, E. B.; Kushch, L. A.; Gritsenko, V. V.; Dyachenko, O.
A.; Buravov, L. I.; Khomenko, A. G. Synth. Metals 1995, 70, 1039.
(55) Yagubskii, E. B., Kotov, A. I.; Laukhina, E. E.; Ignatiev, A. A.;
Khomenko, A. G.; Nahapetyan, S. S.; Shklover, B. E.; Struchkov,
Yu. T.; Vetoshkina, L. V.; Ukhin, L. Yu. Mater. Sci. 1991, 17, 55.
(56) Bard, A.; Faulkner, L. R. Electrochemical Methods; J. Wiley &
Sons: New York, 1980.
(57) Schrauzer, G. N. Acc. Chem. Res. 1969, 2, 72.

Metal Complexes of Dithiolate Ligands
Inorganic Chemistry, Vol. 35, No. 13, 1996 3867
Figure 11. (a) Cyclic voltammogram of (NMe4)[Ni(dtdt)2] (10-3 M) in CH3CN/(NMe4)BF4 (10-1 M) at a Pt electrode (1 mm) with a scan rate of
0.1 V s-1 [potential in volts Vs Ag/AgCl (* starting potential)]. (b) Cyclic voltammogram at a Pt electrode (100 µm) with a scan rate of 800 V s-1
.
(c) Linear voltammogram of (NMe4)[Ni(dtdt)2] (10-3 M) in CH3CN/(NMe4)BF4 (10-1 M) at a Pt electrode (2 mm) with a scan rate of 5 mV s-1
[potential in volts Vs Ag/AgCl]. (d) Cyclic voltammogram of (NMe4)[Ni(dtdt)2] (7 × 10-4 M) in C6H5CN/(NMe4)BF4 (10-1 M) at a Pt electrode
(0.5 mm) with a scan rate of 0.1 V s-1 [potential in volts Vs Ag/AgCl (* starting potential)].
Table 12. Selected Bond Distances and Angles (deg) for [Pt(dddt)2][Ni(dmit)2]2 (4)
Pt(1)-S(11)
Ni(1)-S(1)
Ni(1)-S(2)
Ni(1)-S(6)
Ni(1)-S(7)
S(1)-C(1)
S(2)-C(2)
2.244(3)
2.140(4)
2.135(4)
2.128(4)
2.132(4)
1.68(2)
S(3)-C(1)
S(3)-C(3)
S(4)-C(2)
S(4)-C(3)
S(5)-C(3)
S(6)-C(4)
S(7)-C(5)
1.74(2)
1.73(2)
1.72(1)
1.75(2)
1.61(2)‘
1.64(2)
1.66(1)
S(8)-C(4)
S(8)-C(6)
S(9)-C(5)
S(9)-C(6)
S(10)-C(6)
S(11)-C(7)
S(12)-C(7)
1.76(1)
1.73(2)
1.71(1)
1.75(1)
1.59(2)
1.685(9)
1.7343(9)
S(12)-C(8)
S(12)-C(9)
C(1)-C(2)
C(4)-C(5)
C(7)-C(7)
C(8)-C(9)
1.77(3)
1.83(3)
1.38(2)
1.43(2)
1.40(2)
1.56(3)
1.69(2)
S(11)-Pt(1)-S(11)
S(1)-Ni(1)-S(2)
S(6)-Ni(1)-S(7)
Ni(1)-S(1)-C(1)
Ni(1)-S(2)-C(2)
C(1)-S(3)-C(3)
C(2)-S(4)-C(3)
Ni(1)-S(6)-C(4)
Ni(1)-S(7)-C(5)
C(4)-S(8)-C(6)
C(5)-S(9)-C(6)
92.1(1)
Pt(1)-S(11)-C(7)
C(7)-S(12)-C(8)
C(7)-S(12)-C(9)
S(1)-C(1)-C(2)
S(3)-C(1)-C(2)
S(2)-C(2)-S(4)
S(2)-C(2)-C(1)
S(4)-C(2)-C(1)
S(3)-C(3)-S(4)
S(3)-C(3)-S(5)
S(4)-C(3)-S(5)
105.5(4)
S(6)-C(4)-C(5)
122.2(11)
113.3(11)
117.9(11)
116.4(11)
112.2(9)
123.5(9)
124.3(10)
120.6(4)
125.3(3)
110.5(18)
114.3(20)
93.1(2)
93.0(2)
102.3(6)
102.9(5)
98.0(7)
97.8(8)
102.8(6)
104.1(5)
99.2(7)
98.9(7)
103.3(10)
107.4(10)
121.7(12)
115.8(11)
124.0(9)
119.9(11)
116.0(12)
112.4(9)
S(8)-C(4)-C(5)
S(7)-C(5)-C(4)
S(9)-C(5)-C(4)
S(8)-C(6)-S(9)
S(8)-C(6)-S(10)
S(9)-C(6)-S(10)
S(11)-C(7)-C(7)
S(12)-C(7)-C(7)
S(12)-C(8)-C(9)
S(12)-C(9)-C(8)
123.6(10)
124.0(11)
is not very favorable for high conductivity and explains the low
value of the measured powder conductivity for this compound
(5 × 10-5 S cm-1). It is interesting to note that 4 is one of the
rare donor-acceptor compounds8 in which both the donor and
acceptor molecules are transition metal complexes. Even in
the present case, both donor and acceptor are complexes of 1,2-
dithiolate ligands.
been prepared by galvanostatic electrolysis of solutions of the
monovalent (PPN)[M(dmit)2] and (BTP)[M(dmit)2] complexes
in acetone, acetonitrile, or 1,1,2-trichloroethane. Elemental
analyses are compatible with a (cation)[M(dmit)2]z stoichiometry
with z ≈ 3. This was confirmed in the case of (BTP)[Ni(dmit)2]3
(5), for which crystal quality was sufficient for an X-ray
structure determination.
(PPN)[M(dmit)2]z and (BTP)[M(dmit)2]z Compounds. The
results of the electrochemical studies discussed earlier clearly
show that the (cation)[M(dmit)2] complexes studied may be used
for the preparation of (cation)[Ni(dmit)2]z NIOS radical anion
salts. (PPN)[M(dmit)2]n complexes with M ) Te, Se and n )
2, 1 have been previously reported,58 but no derived NIOS
compounds. The (TTP)[Ni(dmit)2]3 (TTP+ ) tetraphenylphos-
phonium) radical anion salt has been reported very recently.59
In this work, plate-shaped crystals of the (PPN)[M(dmit)2]z
and (BTP)[M(dmit)2]z radical anion salts with M ) Ni, Pd have
The asymmetric unit of (BTP)[Ni(dmit)2]3 (5) contains three
crystallographically independent [Ni(dmit)2] entities and one
BTP+ cation. Selected bond lengths and angles are listed in
Table 13. The averaged NisS, inner SsC, and CdC bond
lengths [2.162, 1.707, and 1.39 Å for the Ni(1) unit, 2.155,
1.697, and 1.392 Å for the Ni(2) unit, and 2.147, 1.703, and
1.387 Å for the Ni(3) unit] do not show significant differences
between the three independent [Ni(dmit)2] units. From this
observation, it can be anticipated that the negative charge is
totally delocalized over the three [Ni(dmit)2] units. The almost
planar [Ni(dmit)2] units form stacks along the [102] direction
(Figure 13) separated by the BTP+ cations, which are located
close to the external sulfur atoms of the thione group of the
(58) Singh, D. J.; Singh, H. B. Polyhedron 1993, 12, 2849.
(59) Nakamura, T.; Underhill, A. E.; Coomber, A. T.; Friend, R. H.; Tajima,
H.; Kobayashi, A.; Kobayashi, H. Inorg. Chem. 1995, 34, 870.

3868 Inorganic Chemistry, Vol. 35, No. 13, 1996
Faulmann et al.
(with y ) 0, 1, 2, 3 and M ) Ni, Pd) by galvanostatic
electrolysis of solutions of the monovalent (SMeyEt3-y)[Ni(dmit)2]
complexes and the divalent (SMeyEt3-y)2[Pd(dmit)2] complexes
(the corresponding monovalent palladium complexes could not
be isolated, Vide supra) in mixtures of acetonitrile and ethyl
alcohol or acetone.
The quality of the needle-shaped crystals of (SMe3)[Ni-
(dmit)2]2 (6) was sufficient for X-ray structure determination.
The unit cell parameters (space group P1h, a ) 7.882(1) Å, b )
11.603(2) Å, c ) 17.731(2) Å, R ) 77.44(1)°, â ) 85.86(1)°,
γ ) 81.27(1)°, Z ) 2) were found to be equivalent to those
previously reported.61,63 Selected bond lengths and angles are
listed in Table 14. The (SMe3)+ cations are statistically
distributed between two positions related by a center of
symmetry. The Ni(dmit)2 units stack along the [100] direction.
The stacking arrangement is shown in Figure 15a. Within these
stacks, the interplanar distances are alternately 3.49 and 3.61
Å (Figure 15b). These stacks form layers parallel to the (001)
plane and these layers alternate with the (SMe3)+ cations layers
along the [001] direction. As are usually observed in M(dmit)2
compounds, a number of S‚‚‚S interatomic distances shorter than
the sum of the van der Waals radii (3.70 Å) are observed
between molecules belonging to adjacent stacks (Figure 15a).
The room temperature conductivity of the needle-shaped
crystals of (SMe3)[Ni(dmit)2]2 is 0.15 S cm-1, and the compound
behaves as a semiconductor with an activation energy of 0.12
eV (supplementary material, Figure S3). The room temperature
conductivity of the needle-shaped crystals of (SMeEt2)[Ni-
(dmit)2]z is also moderate (0.6 S cm-1), and this compound is
also a semiconductor with an activation energy of 0.11 eV. The
room temperature conductivity of the plate-shaped crystals of
(SEt3)[Ni(dmit)2]z is somewhat higher (10 S cm-1). It is also
a semiconductor. Two regimes are observed in the temperature
dependence of the conductivity with activation energies of 0.05
eV from 300 to 220 K and 0.18 eV from 220 to 115 K.
The unit cell of (SMeEt2)[Pd(dmit)2]2 (7) contains two
crystallographically independent Pd(dmit)2 units and one
(SMeEt2)+ cation. Selected bond distances and angles are given
in Table 15. Within the esds, the averaged intramolecular
distances are almost identical in both Pd(dmit)2 units. Each
Pd(dmit)2 unit forms segregated stacks along the [100] direction
(Figure 16a). The stacks formed by one of the independent
Pd(dmit)2 unit are connected to the stacks formed by the other
independent Pd(dmit)2 unit through its terminal sulfur atoms
along the [010] direction. In a stack, the Pd(dmit)2 entities are
paired, forming [Pd(dmit)2]2 dimers with a Pd-Pd bond length
of 3.131(2) and 3.138(2) Å. Thus, the structure consists of
layers of [Pd(dmit)2]2 dimers parallel to the ac plane, connected
to each other through short S‚‚‚S contacts (Figure 16b) and
separated by sheets of (SMeEt2)+ cations. The Pd(dmit)2 entities
are eclipsed within a dimer and slipped between dimers, with
interplanar distances of 3.50 and 3.59 Å, respectively (Figure
16c).
Figure 12. [Pt(dddt)2][Ni(dmit)2]2 (4): (a) projection onto the ac plane;
(b) stacking arrangement [dotted lines represent the S‚‚‚S distances
shorter than the sum of the van der Waals radii (3.70 Å)].
[Ni(dmit)2] units. The repeat unit along a stack is characterized
by three interplanar distances of 3.59, 3.59, and 3.54 Å (Figure
13) and three modes of overlap pictured in Figure 14; two of
them result from mainly longitudinal and slightly transverse
offsets, resulting in reduced π interactions along the stacks.60
In the same way, most of the short (e3.7 Å) S‚‚‚S contacts
occur between molecules belonging to adjacent stacks (Figure
13).
It is interesting to note that the structural arrangement of 5 is
totally different from that observed for the parent compound
(TTP)[Ni(dmit)2]3, which also has a phosphonium countercation
(tetraphenylphosphonium instead of benzyltriphenylphospho-
nium) and the same 1/3 stoichiometry.59 In (TTP)[Ni(dmit)2]3,
two Ni(dmit)2 units form stacks along the [010] direction, and
another Ni(dmit)2 unit is almost perpendicular to the stacks.59
The single-crystal conductivity of (BTP)[Ni(dmit)2]3 (5) is
modest (0.2 S cm-1) compared to that of (BTP)[Pd(dmit)2]z (80
S cm-1), (PPN)[Ni(dmit)2]z (45 S cm-1), and (PPN)[Pd(dmit)2]z
(62 S cm-1). All of these compounds behave as semiconductors
(supplementary material, Figure S2). The activation energy of
(PPN)[Ni(dmit)2]z is rather small (≈0.05 eV), resulting in a high
residual conductivity at low temperature (0.15 S cm-1 at 70
K).
By contrast with (SMe3)[Ni(dmit)2]2 , the room temperature
conductivity of the plate-shaped crystals of (SMeEt2)[Pd(dmit)2]2
is very high (100 S cm-1). The temperature dependence of the
(SMeyEt3-y)[M(dmit)2]z Compounds. The preparation of
(SMe3)[Ni(dmit)2]2 has been mentioned previously,61 and
(SMe3)[Au(dmit)2]z and (SBu3)[Au(dmit)2]z phases have been
reported to exhibit high metal-like conductivities.62 We have
prepared all the members of the (SMeyEt3-y)[M(dmit)2]z series
(63) Kobayashi et al. have reported in ref 61 the following unit cell
parameters for (SMe3)[Ni(dmit)2]2: space group P1h, a ) 20.330(1)
Å, b ) 11.598(5) Å, c ) 7.883(4) Å, R ) 98.62(4)°, â ) 111.14(5)°,
γ ) 108.81(5)°, Z ) 2). During the writing of this manuscript, we
became aware that the structure of this compound had been solved
simultaneously by Liu et al. (Liu, H. L.; Tanner, D. B.; Pullen, A. E.;
Abboud, K. A.; Reynolds, J. R. Personal communication, submitted
for publication in Phys. ReV. B). They report the following unit cell
parameters: space group P1h, a ) 7.923(1) Å, b ) 11.647(5) Å, c )
17.812(2) Å, R ) 77.46(1)°, â ) 85.93(1)°, γ ) 81.36(1)°, Z ) 2.
The main features of this structure are essentially similar to those
reported in the present work.
(60) Kobayashi, A.; Kim, A.; Sasaki, H.; Kato, R.; Kobayashi, H. Solid
State Commun. 1987, 62, 57.
(61) Kato, R.; Kobayashi, H.; Kim, H.; Kobayashi, A.; Sasaki, Y.; Mori,
T.; Inokuchi, H. Synth. Metals 1988, 27B, 359.
(62) Yagubskii, E. B.; Ukhin, L. Yu.; Kotov, A. I. Dokl. An. SSSR 1986,
290, 115.

Metal Complexes of Dithiolate Ligands
Inorganic Chemistry, Vol. 35, No. 13, 1996 3869
Table 13. Selected Bond Distances and Angles (deg) for (BTP)[Ni(dmit)2]3 (5)
Ni(1)-S(1)
Ni(1)-S(2)
Ni(1)-S(6)
Ni(1)-S(7)
Ni(2)-S(11)
Ni(2)-S(12)
Ni(2)-S(16)
Ni(2)-S(17)
Ni(3)-S(21)
Ni(3)-S(22)
Ni(3)-S(26)
Ni(3)-S(27)
S(1)-C(1)
2.154(2)
2.161(2)
2.163(2)
2.168(2)
2.156(2)
2.158(2)
2.159(2)
2.148(2)
2.153(2)
2.145(2)
2.148(2)
2.141(2)
1.704(6)
1.708(6)
1.731(7)
S(3)-C(3)
S(4)-C(2)
S(4)-C(3)
S(5)-C(3)
S(6)-C(4)
S(7)-C(5)
S(8)-C(4)
S(8)-C(6)
S(9)-C(5)
S(9)-C(6)
S(10)-C(6)
S(11)-C(7)
S(12)-C(8)
S(13)-C(7)
S(13)-C(9)
1.732(7)
1.725(6)
1.738(7)
1.632(7)
1.703(7)
1.712(7)
1.729(7)
1.735(8)
1.723(7)
1.725(8)
1.642(8)
1.698(7)
1.707(7)
1.734(7)
1.752(8)
S(14)-C(8)
S(14)-C(9)
S(15)-C(9)
S(16)-C(10)
S(17)-C(11)
S(18)-C(10)
S(18)-C(12)
S(19)-C(11)
S(19)-C(12)
S(20)-C(12)
S(21)-C(13)
S(22)-C(14)
S(23)-C(13)
S(23)-C(15)
S(24)-C(14)
1.733(7)
1.730(8)
1.634(8)
1.697(7)
1.685(6)
1.739(7)
1.739(7)
1.730(6)
1.737(7)
1.626(7)
1.693(7)
1.677(7)
1.729(7)
1.750(8)
1.727(7)
S(24)-C(15)
S(25)-C(15)
S(26)-C(16)
S(27)-C(17)
S(28)-C(16)
S(28)-C(18)
S(29)-C(17)
S(29)-C(18)
S(30)-C(18)
C(1)-C(2)
1.749(8)
1.608(8)
1.693(7)
1.707(7)
1.734(7)
1.729(8)
1.730(7)
1.727(8)
1.629(8)
1.386(9)
1.40(1)
C(4)-C(5)
C(7)-C(8)
1.390(9)
1.394(9)
1.405(9)
1.369(9)
C(10)-C(11)
C(13)-C(14)
C(16)-C(17)
S(2)-C(2)
S(3)-C(1)
S(1)-Ni(1)-S(2)
S(6)-Ni(1)-S(7)
92.68(7)
C(13)-S(23)-C(15)
C(14)-S(24)-C(15)
Ni(3)-S(26)-C(16)
Ni(3)-S(27)-C(17)
C(16)-C(28)-C(18)
C(17)-C(29)-C(18)
S(1)-C(1)-C(2)
S(3)-C(1)-C(2)
S(2)-C(2)-C(1
S(4)-C(2)-C(1)
S(3)-C(3)-S(4)
S(3)-C(3)-S(5)
S(4)-C(3)-S(5)
S(6)-C(4)-C(5)
S(8)-C(4)-C(5)
S(7)-C(5)-C(4)
S(9)-C(5)-C(4)
S(8)-C(6)-S(9)
S(8)-C(6)-S(10)
S(9)-C(6)-S(10)
S(11)-C(7)-C(8)
S(13)-C(7)-C(8)
S(12)-C(8)-C(7)
S(14)-C(8)-C(7)
97.6(3)
S(13)-C(9)-S(14)
112.8(4)
123.5(5)
123.6(5)
120.8(5)
115.8(5)
120.6(5)
115.7(5)
113.2(4)
123.5(4)
123.3(4)
120.3(5)
116.1(5)
120.8(5)
115.7(5)
112.7(4)
124.5(5)
122.8(5)
121.5(5)
115.6(5)
120.2(5)
116.7(5)
113.8(4)
123.8(5)
122.4(5)
93.06(8)
93.18(7)
92.81(7)
92.99(7)
93.15(7)
103.1(2)
103.0(2)
97.3(3)
97.9(3)
102.4(2)
102.7(2)
97.0(4)
S(13)-C(9)-S(15)
S(14)-C(9)-S(15)
S(16)-C(10)-C(11)
S(18)-C(10)-C(11)
S(17)-C(11)-C(10)
S(19)-C(11)-C(10)
S(18)-C(12)-S(19)
S(18)-C(12)-S(20)
S(19)-C(12)-S(20)
S(21)-C(13)-C(14)
S(23)-C(13)-C(14)
S(22)-C(14)-C(13)
S(24)-C(14)-C(13)
S(23)-C(15)-S(24)
S(23)-C(15)-S(25)
S(24)-C(15)-S(25)
S(26)-C(16)-C(17)
S(28)-C(16)-C(17)
S(27)-C(17)-C(16)
S(29)-C(17)-C(16)
S(28)-C(18)-S(29)
S(28)-C(18)-S(30)
S(29)-C(18)-S(30)
S(11)-Ni(2)-S(12)
S(16)-Ni(2)-S(17)
S(21)-Ni(3)-S(22)
S(26)-Ni(3)-S(27)
Ni(1)-S(1)-C(1)
Ni(1)-S(2)-C(2)
C(1)-S(3)-C(3)
96.7(4)
120.8(5)
116.0(5)
120.3(5)
116.0(5)
113.4(4)
123.3(4)
123.3(4)
121.3(5)
114.8(5)
120.1(5)
116.4(5)
113.4(4)
122.7(5)
123.9(5)
120.8(5)
115.8(5)
120.8(5)
115.8(5)
C(2)-S(4)-C(3)
97.3(3)
Ni(1)-S(6)-C(4)
Ni(1)-S(7)-C(5)
C(4)-S(8)-C(6)
102.7(2)
102.8(2)
97.8(4)
C(5)-S(9)-C(6)
97.5(4)
Ni(2)-S(11)-C(7)
Ni(2)-S(12)-C(8)
C(7)-S(13)-C(9)
C(8)-S(14)-C(9)
Ni(2)-S(16)-C10)
Ni(2)-S(17)-C(11)
C(10)-S(18)-C(12)
C(11)-S(19)-C(12)
Ni(3)-S(21)-C(13)
Ni(3)-S(22)-C(14)
102.8(2)
102.4(2)
97.4(3)
97.9(3)
102.5(2)
103.3(2)
97.5(3)
97.9(3)
102.7(2)
103.2(2)
Figure 13. (BTP)[Ni(dmit)2]3 (5): stacking of the Ni(dmit)2 entities
along [102].
conductivity of this compound is shown in Figure 17. The
behavior is that of a pseudometal from 300 down to 150 K and
increases slightly up to 108 S cm-1. At ≈150 K, the compound
undergoes a transition to a semiconducting state. However, this
behavior is not reversible when heating back to room temper-
ature and on subsequent cooling cycles, whereby the compound
remains semiconducting over the whole temperature range. This
behavior is reminiscent of that of the superconducting R-(TTF)-
[Pd(dmit)2]2 phase.19c
Electronic Structure of (SMeEt2)[Pd(dmit)2]2. Despite the
similarities in resistivity behavior between (SMeEt2)[Pd(dmit)2]2
and R-(TTF)[Pd(dmit)2]2,19c there are two subtle but important
differences in the structure of the acceptor layers of these
Figure 14. Different modes of molecular overlap within the Ni(dmit)2
stacks of (BTP)[Ni(dmit)2]3 (5).
salts.19c,20 First, the Pd(dmit)2 stacks are uniform in the latter,
but contain [Pd(dmit)2]2 diads in the former. Second, the two
acceptor layers of the unit cell in R-(TTF)[Pd(dmit)2]2 are related
by a symmetry element and thus are equivalent, whereas in
(SMeEt2)[Pd(dmit)2]2 the unit cell contains two crystallographi-
cally independent Pd(dmit)2 units.
The calculated band structures for the two different acceptor
layers of (SMeEt2)[Pd(dmit)2]2 are shown in Figure 18. The

3870 Inorganic Chemistry, Vol. 35, No. 13, 1996
Faulmann et al.
Table 14. Selected Bond Distances and Angles (deg) for (SMe3)[Ni(dmit)2]2 (6)
Ni(1)-S(1)
Ni(1)-S(2)
Ni(1)-S(6)
Ni(1)-S(7)
S(1)-C(1)
2.153(2)
2.151(2)
2.163(2)
2.162(2)
1.693(7)
S(2)-C(2)
S(3)-C(1)
S(3)-C(3)
S(4)-C(2)
S(4)-C(3)
1.686(7)
1.729(7)
1.721(8)
1.723(8)
1.717(7)
S(5)-C(3)
S(6)-C(4)
S(7)-C(5)
S(8)-C(4)
S(8)-C(6)
1.650(8)
1.695(8)
1.691(7)
1.742(7)
1.724(8)
S(9)-C(5)
S(9)-C(6)
S(10)-C(6)
C(1)-C(2)
C(4)-C(5)
1.746(8)
1.733(7)
1.648(8)
1.388(8)
1.38(1)
Ni(11)-S(11)
Ni(11)-S(12)
Ni(11)-S(16)
Ni(11)-S(17)
S(11)-C(11)
2.152(2)
2.158(2)
2.154(2)
2.161(2)
1.700(8)
S(12)-C(12)
S(13)-C(11)
S(13)-C(13)
S(14)-C(12)
S(14)-C(13)
1.709(7)
1.735(7)
1.706(9)
1.736(8)
1.730(7)
S(15)-C(13)
S(16)-C(14)
S(17)-C(15)
S(18)-C(14)
S(18)-C(16)
1.659(8)
1.688(7)
1.689(7)
1.735(7)
1.731(8)
S(19)-C(15)
S(19)-C(16)
S(20)-C(16)
C(11)-C(12)
C(14)-C(15)
1.746(7)
1.725(7)
1.637(8)
1.360(9)
1.366(9)
S(1)-Ni(1)-S(2)
S(6)-Ni(1)-S(7)
Ni(1)-S(1)-C(1)
Ni(1)-S(2)-C(2)
C(1)-S(3)-C(3)
C(2)-S(4)-C(3)
Ni(1)-S(6)-C(6)
Ni(1)-S(7)-C(5)
92.63(7)
C(4)-S(8)-C(6)
C(5)-S(9)-C(6)
S(1)-C(1)-C(2)
S(3)-C(1)-C(2)
S(2)-C(2)-C(1)
S(4)-C(2)-C(1)
S(3)-C(3)-S(4)
S(3)-C(3)-S(5)
97.6(3)
S(4)-C(3)-S(5)
122.7(5)
120.8(5)
116.2(6)
122.0(6)
115.1(5)
113.2(4)
124.2(4)
122.6(5)
93.09(7)
102.9(2)
103.0(2)
96.6(3)
97.1(3)
102.2(2)
101.9(3)
97.8(4)
120.5(5)
116.1(5)
120.9(6)
115.6(5)
114.5(4)
122.7(4)
S(6)-C(4)-C(5)
S(8)-C(4)-C(5)
S(7)-C(5)-C(4)
S(9)-C(5)-C(4)
S(8)-C(6)-S(9)
S(8)-C(6)-S(10)
S(9)-C(6)-S(10)
S(11)-Ni(11)-S(12)
S(16)-Ni(11)-S(17)
Ni(11)-S(11)-C(11)
Ni(11)-S(12)-C(12)
C(11)-S(13)-C(13)
C(12)-S(14)-C(13)
Ni(11)-S(16)-C(14)
Ni(11)-S(17)-C(15)
93.49(7)
92.97(7)
102.0(2)
101.6(2)
97.4(3)
96.6(4)
102.3(2)
101.7(2)
C(15)-S(19)-C(16)
S(11)-C(11)-C(12)
S(13)-C(11)-C(12)
S(12)-C(12)-C(11)
S(14)-C(12)-C(11)
S(13)-C(13)-S(14)
S(13)-C(13)-S(15)
S(14)-C(13)-S(15)
97.3(3)
121.5(5)
115.7(6)
121.3(6)
116.3(5)
114.0(5)
123.6(4)
122.4(5)
S(16)-C(14)-C(15)
S(18)-C(14)-C(15)
S(17)-C(15)-C(14)
S(19)-C(15)-C(14)
S(18)-C(16)-S(19)
S(18)-C(16)-S(20)
121.0(5)
116.2(5)
121.9(6)
115.6(5)
113.4(4)
121.9(4)
for the layer containing diads with a Pd‚‚‚Pd bond length of
3.138(2) Å (layer 2) are shown as dashed lines. As usual, in
M(dmit)2 salts with strong dimerization,64-67 the lowest com-
bination of the two Pd(dmit)2 LUMOs (Ψ+LUMO) is lower in
energy than the highest combination of the two Pd(dmit)2
HOMOs (Ψ-HOMO). The intermolecular interactions within the
two acceptor slabs of (SMeEt2)[Pd(dmit)2]2 do not change this
level ordering, so that the third pair of bands from the bottom
of Figure 18, i.e., the bands that are partially filled, is the
Ψ-
bands.
HOMO
Since there is a short interlayer S‚‚‚S contact in (SMeEt2)-
[Pd(dmit)2]2, we have also carried out calculations for the three-
dimensional acceptor lattice. However, the band dispersion
along the interlayer direction is very small, and the calculated
3D band structure is practically the superposition of the band
structures of the two slabs. Consequently, from now on, our
discussion will be based on the results of Figure 18. The most
interesting result of this band structure is that the bands of layer
2 are always at slightly lower energies than those of layer 1.
Consequently, the filling of the partially filled band of layers 1
and 2, i.e., the associated charge transfer, must be different.
According to our calculations, the number of electrons trans-
1
ferred per Pd(dmit)2 unit (F) is approximately /3 for layer 1
and 2/3 for layer 2. The two partially filled bands of Figure 18
are completely parallel and shifted by ≈0.08 eV. Thus, the
interdiad interactions in both layers must be almost identical
and are not at the origin of the different charge transfer. The
energy difference between the HOMOs of the Pd(dmit)2
molecules in both layers is 0.095 eV, with the energy of the
HOMOs of the Pd(dmit)2 in layer 2 being lower. The splitting
between the two HOMO levels of the diads (Ψ+
and
HOMO
Ψ-HOMO) in both layers differs by only 0.008 eV. Conse-
quently, the difference between the partially filled bands of both
layers originates from slight geometrical differences between
the corresponding Pd(dmit)2 molecules. This somewhat surpris-
ing difference in the charge transfer for the two layers, which
is not revealed by important geometrical differences, is due to
the nonexistence of a symmetry element relating both layers.
Given the accuracy of the crystal structure, the 2/3 and 1/3 values
for F evidently should be taken as indicative, and their difference
can be considered an upper limit.
Figure 15. (SMe3)[Ni(dmit)2]2 (6): (a) stacking of the Ni(dmit)2] units
along the [100] direction with the network of S‚‚‚S distances shorter
than the sum of the van der Waals radii (3.70 Å) (dotted lines); (b) the
two different modes of molecular overlap within the Ni(dmit)2 stacks.
bands for the layer containing diads with a Pd‚‚‚Pd bond length
of 3.131(2) Å (layer 1) are shown as continuous lines; those

Metal Complexes of Dithiolate Ligands
Inorganic Chemistry, Vol. 35, No. 13, 1996 3871
Table 15. Selected Bond Distances and Angles (deg) for (SMeEt2)[Pd(dmit)2]2 (7)
Pd(1)-Pd(1)
Pd(1)-S(11)
Pd(1)-S(12)
Pd(1)-S(16)
Pd(1)-S(17)
Pd(2)-Pd(2)
Pd(2)-S(21)
Pd(2)-S(22)
Pd(2)-S(26)
Pd(2)-S(27)
S(11)-C(11)
3.131(2)
2.305(4)
2.289(3)
2.283(4)
2.293(3)
3.138(2)
2.296(3)
2.287(4)
2.288(4)
2.295(4)
1.68(1)
S(12)-C(12)
S(13)-C(11)
S(13)-C(13)
S(14)-C(12)
S(14)-C(13)
S(15)-C(13)
S(16)-C(14)
S(17)-C(15)
S(18)-C(14)
S(18)-C(16)
S(19)-C(15)
1.70(1)
1.73(1)
1.74(2)
1.73(1)
1.72(2)
1.63(2)
1.69(1)
1.69(1)
1.71(1)
1.70(1)
1.75(1)
S(19)-C(16)
S(20)-C(16)
S(21)-C(21)
S(22)-C(22)
S(23)-C(21)
S(23)-C(23)
S(24)-C(22)
S(24)-C(23)
S(25)-C(23)
S(26)-C(24)
S(27)-C(25)
1.75(2)
1.62(2)
1.71(1)
1.69(1)
1.75(1)
1.74(1)
1.73(1)
1.71(1)
1.64(1)
1.70(1)
1.71(1)
S(28)-C(24)
S(28)-C(26)
S(29)-C(25)
S(29)-C(26)
S(30)-C(26)
C(11)-C(12)
C(14)-C(15)
C(21)-C(22)
C(24)-C(25)
1.73(1)
1.74(2)
1.74(1)
1.72(2)
1.64(2)
1.39(2)
1.38(2)
1.35(2)
1.37(2)
S(11)-Pd(1)-S(12)
S(16)-Pd(1)-S(17)
Pd(2)-Pd(2)-S(21)
Pd(2)-Pd(2)-S(22)
S(21)-Pd(2)-S(22)
Pd(2)-Pd(2)-S(26)
Pd(2)-Pd(2)-S(27)
S(26)-Pd(2)-S(27)
Pd(1)-S(11)-C(11)
Pd(1)-S(12)-C(12)
C(11)-S(13)-C(13)
C(12)-S(14)-C(13)
Pd(1)-S(16)-C(14)
Pd(1)-S(17)-C(15)
C(14)-S(18)-C(16)
C(15)-S(19)-C(16)
Pd(2)-S(21)-C(21)
Pd(2)-S(22)-C(22)
89.9(1)
89.8(1)
91.6(1)
92.0(1)
89.8(1)
91.5(1)
91.9(1)
90.1(1)
101.4(5)
102.0(4)
98.8(7)
98.0(7)
102.8(5)
101.0(5)
99.0(7)
96.9(7)
100.6(5)
101.9(5)
C(21)-S(23)-C(23)
C(22)-S(24)-C(23)
Pd(2)-S(26)-C(24)
Pd(2)-S(27)-C(25)
C(24)-S(28)-C(26)
C(25)-S(29)-C(26)
S(1)-C(2)-C(3)
96.0(7)
97.8(7)
102.1(5)
101.0(5)
97.6(7)
S(19)-C(15)-C(14)
115.1(11)
112.9(8)
124.9(10)
122.1(9)
124.4(10)
116.6(11)
123.2(11)
115.9(10)
113.4(8)
121.7(8)
124.6(9)
122.3(10)
115.9(10)
124.4(10)
115.7(10)
113.1(9)
122.6(10)
124.3(10)
S(18)-C(16)-S(19)
S(18)-C(16)-S(20)
S(19)-C(16)-S(20)
S(21)-C(21)-C(22)
S(23)-C(21)-C(22)
S(22)-C(22)-C(21)
S(24)-C(22)-C(21)
S(23)-C(23)-S(24)
S(23)-C(23)-S(25)
S(24)-C(23)-S(25)
S(26)-C(24)-C(25)
S(28)-C(24)-C(25)
S(27)-C(25)-C(24)
S(29)-C(25)-C(24)
S(28)-C(26)-S(29)
S(28)-C(26)-S(30)
S(29)-C(26)-S(30)
97.7(7)
108.9(24)
106.5(21)
124.4(10)
114.2(10)
122.3(10)
116.7(10)
112.4(9)
123.3(10)
124.2(10)
121.6(11)
116.0(10)
124.7(10)
S(1)-C(4)-C(5)
S(11)-C(11)-C(12)
S(13)-C(11)-C(12)
S(13)-C(12)-C(11)
S(14)-C(12)-C(11)
S(13)-C(13)-S(14)
S(13)-C(13)-S(15)
S(14)-C(13)-S(15)
S(16)-C(14)-C(15)
S(18)-C(14)-C(15)
S(17)-C(15)-C(14)
Figure 16. (SMeEt)2[Pd(dmit)2]2 (7): (a) projection on the ab plane; (b) stacking arrangement within the Pd units [dotted lines represent the S‚‚‚S
distances shorter than the sum of the van der Waals radii (3.70 Å), and S‚‚‚S distances represented with - ‚ - are observed only for the Pd(1)
units]; (c) the two different modes of molecular overlap within the Pd(dmit)2 stacks.
Unlike in the organic systems based on TTF-like molecules
of the oxidation state of the donor, we have previously shown
where the central CdC bond length is quite a good indicator
that the MsS bond length in M(dmit)2-based systems should

3872 Inorganic Chemistry, Vol. 35, No. 13, 1996
Faulmann et al.
Figure 17. Temperature dependence of the conductivity of (SMeEt)2-
[Pd(dmit)2]2 (7): (a) decreasing temperature; (b) increasing temperature.
Figure 19. Calculated Fermi surfaces for the two Pd(dmit)2 layers of
(SMeEt2)[Pd(dmit)2]2: (a) layer 1 and F ) 1/3; (b) layer 2 and F ) 2/3;
1
(c) layer 1 and F ) 1/2; and (d) layer 2 and F ) /2.
[Pd(dmit)2]2 should be a 2D metal (or a pseudo-2D metal
depending on the charge transfer) with a better conductivity
along the c direction. Moreover, the conductivity anisotropy
should be larger when the difference in charge transfer between
the two layers decreases.
Figure 18. Dispersion relations calculated for the HOMO and LUMO
bands of the two Pd(dmit)2 layers in (SMeEt2)[Pd(dmit)2]2. The bands
of layer 1 (see text) are shown as continuous lines, whereas those of
layer 2 are shown as dashed lines. Γ, X, Z, and S refer to the wave
vectors (0, 0), (a*/2, 0), (0, c*/2), and (-a*/2, c*/2), respectively.
Charge transfer salts containing Pd(dmit)2 layers with F ≈
1/2 may exhibit quite different properties although their structures
are similar.65,68-70 For example, whereas Cs[Pd(dmit)2]265 and
δ-TTF[Pd(dmit)2]268 are metallic at room temperature, (PMe4)-
[Pd(dmit)2]269 and â-(NMe4)[Pd(dmit)2]270 are room temperature
semiconductors. Moreover, even if both Cs[Pd(dmit)2]2 and
δ-TTF[Pd(dmit)2]2 undergo a metal-insulator transition,65,68 the
origin of the two transitions is different. X-ray diffuse scattering
studies have shown that whereas the first one is a structural
Peierls type transition,65 the second one occurs without any
structural change.71 In all of these cases, the Mott-Hubbard
interactions for these salts are of the same order of magnitude
as the Ψ-HOMO bandwidth, and, hence, the metallic and localized
states are in strong competition.64 This is consistent with the
be quite insensitive to the oxidation state of the M(dmit)2
acceptor.47,64 Moreover, as is the case for all other metallic
Pd(dmit)2 layers containing diads, and as a consequence of the
interdiad slipping (see Figure 16c), the dispersion of the Ψ-
HOMO
band along the chain direction (Γ f X in Figure 18) is not
large (i.e., the interdiad interactions within the chains are weaker
than those along the interchain direction). Thus, a relatively
small energy shift between the two Ψ-HOMO bands can lead to
sizable differences in their electron filling. In addition, accord-
ing to the nature of the HOMOs of Pd(dmit)2, as the charge
transfer toward the Ψ-
band increases, the main effect
HOMO
should be a small shortening of the CdC bond lengths and a
smaller lengthening of the inner CsS and terminal CdS bond
lengths. Indeed, all of these trends may be found when
comparing the geometries of the Pd(dmit)2 units of layers 1 and
2 (see Table 15). Thus, we conclude that although it might be
overestimated the difference in the charge transfers for the two
layers is a real fact.
inversion of the Ψ+
and Ψ-
levels observed for all
LUMO
HOMO
of these slabs. Thus, the interaction between the two Pd(dmit)2
of the diad is strong, and, consequently, the essential building
1
block of the slab is one such diad. If F ) /2, there is one
electron per [Pd(dmit)2]2 diad, which formally corresponds to
a 1/1 charge transfer salt where one electron is localized in each
unit of the lattice. For Pd(dmit)2 layers built from [Pd(dmit)2]2
The calculated Fermi surfaces for layer 1 (F ) 1/3) and layer
2 (F ) 2/3) are shown in Figure 19a,b, respectively. Also shown
in Figure 19c,d are the calculated Fermi surfaces assuming the
(65) Underhill, A. E.; Clark, R. A.; Marsden, I.; Allan, M.; Friend, R. H.;
Tajima, H.; Naito, T.; Tamura, M.; Kuroda, H.; Kobayashi, A.;
Kobayashi, H.; Canadell, E.; Ravy, S.; Pouget, J.-P. J. Phys.: Condens.
Matter 1991, 3, 933.
(66) Pomare`de, B.; Garreau, B.; Malfant, I.; Valade, L.; Cassoux, P.; Legros,
J.-P.; Audouard, A.; Brossard, L.; Ulmet, J.-P.; Doublet, M.-L.;
Canadell, E. Inorg. Chem. 1994, 33, 3401.
1
same charge transfer (F ) /2) for both layers. Whereas the
Fermi surface of Figure 19b is closed, all others are open. The
two Fermi surfaces of Figure 19c,d are practically identical, as
were the interdiad interactions in the two layers (see above).
1
They are relatively well nested by the wave vector q ≈ /4a* +
(67) Doublet, M.-L.; Canadell, E.; Garreau, B.; Legros, J.-P.; Brossard,
L.; Cassoux, P.; Pouget, J.-P. J. Phys.: Condens. Matter 1995, 7, 4673.
(68) Legros, J.-P.; Valade, L. Solid State Commun. 1988, 68, 599. Although
the charge transfer in δ-TTF[Pd(dmit)2]2 has not been unequivocally
demonstrated, the fact that there is no interaction among the TTF
donors and their internal geometry both strongly suggest a charge
1/2c*. Since a transition to a semiconducting state requires the
destruction of the Fermi surfaces of both layers, it is clear that
a Fermi surface instability like a charge density wave is not at
1
the origin of the transition around 150 K (except if F ≈ /2). As
1
the tunneling interaction between the slabs can be neglected,
the real Fermi surface of the material is the superposition of
those of the two layers. Consequently, above 150 K, (SMeEt2)-
transfer of one electron per TTF donor, i.e., F ) /2.
(69) Faulmann, C.; Legros, J.-P.; Cassoux, P.; Cornelissen, J.; Brossard,
L.; Inokuchi, M.; Tajima, H.; Tokumoto, M. J. Chem. Soc., Dalton
Trans. 1994, 249.
(70) Kobayashi, A.; Kim, H.; Sasaki, Y.; Murata, K.; Kato, R.; Kobayashi,
H. J. Chem. Soc., Faraday Trans. 1990, 361.
(71) Ravy, S. Personal communication.
(64) Canadell, E.; Ravy, S.; Pouget, J.-P.; Brossard, L.; Legros, J.-P. Solid
State Commun. 1990, 75, 633.

Metal Complexes of Dithiolate Ligands
Inorganic Chemistry, Vol. 35, No. 13, 1996 3873
diads, there should be a strong tendency for electron localization
with one electron in each diad. The difference from the usual
1/1 charge transfer salts is that, since each unit of the layer
contains two monomers, the intrasite electron repulsion (U)
should be considerably smaller. Consequently, the localized
state is not always the ground state as in 1/1 charge transfer
salts, but competes with the metallic state.
of this work is under way and subject to the availability of
crystals of sufficient size and quality.
However, the basic question concerning the structural and
electronic features that make the M(dmit)2 complexes so unique
that they are the only ones leading to metal complex-based
conductors and superconductors is still unanswered and remains
a contemporary research challenge. The shape, packing ar-
rangement, and redox properties have usefully directed the
investigation toward potential molecule candidates. Electronic
structure determination is irreplaceable either for understanding
some interesting transport properties of a given compound, as
shown in the case of (SMeEt2)[Pd(dmit)2]2, or for explaining
the subtle differences in these properties due to slight changes
in the geometry, as shown by the comparison in this work
between (SMeEt2)[Pd(dmit)2]2 and R-TTF[Pd(dmit)2]2 or previ-
ously between Cs[Pd(dmit)2]2 and δ-TTF[Pd(dmit)2]2.65,71 How-
ever, really unfailing guide rules based on some clear-cut theory
are still to be found. For example, it was generally admitted
that the use of small countercations should enhance the
interaction between the M(dmit)2 units and, hence, the conduc-
tivity. The high conductivity of compounds with bulky cations
such as PPN+ and BTP + and the almost 2 orders of magnitude
increase in the conductivity when going from (SMe3)[Ni(dmit)2]2
to (SEt3)[Ni(dmit)2]z seem to be inconsistent with that prediction.
On the other hand, the higher conductivity of the palladium
compounds compared to the nickel compounds studied here
seems to confirm a general trend previously observed for related
systems.14,15 For the time being, and in the absence of foolproof
guidelines, further research in this field will result, as before,
from serendipitous procedures, and progress will be based on
trial-and-error procedures, involving the design, preparation, and
evaluation of new systems by using empirical selection criteria.
It is clear that metallic charge transfer salts containing Pd-
1
(dmit)2 layers built from [Pd(dmit)2]2 diads and with F ) /2
have a strong tendency to undergo metal-insulator transitions
through either Mott-Hubbard or Fermi surface nesting mech-
anisms, the latter becoming less favorable when F becomes
larger than 1/2. By taking into account (i) the existence of two
symmetry nonequivalent layers in (SMeEt2)[Pd(dmit)2]2 and (ii)
the activated conductivity regime below the transition temper-
ature, it may be suggested that, whatever F is at higher
1
temperature, it becomes ≈ /2 for both layers near 150 K. The
metal-insulator transition at 150 K can be due to either
localization, as presumably occurs for δ-TTF[Pd(dmit)2]2, or a
Peierls transition as in Cs[Pd(dmit)2]2. Magnetic susceptibility
and X-ray diffuse scattering measurements are needed (and are
under progress) to clarify this point. However, the temperature
dependence of the conductivity suggests that localization is more
likely.
In contrast with (SMeEt2)[Pd(dmit)2]2, the HOMO and
LUMO bands of the Pd(dmit)2 layers in the typically one-
dimensional R-TTF[Pd(dmit)2]2 were found to have a strong
dispersion along the stacking direction.47 Moreover, these bands
form two sets of overlapping parallel bands, which are very
well nested. It is clear that the electronic structures of the
R-TTF[Pd(dmit)2]2 and (SMeEt2)[Pd(dmit)2]2 salts are very
different, and, consequently, the reminiscence between the
electrical behaviors of these two salts probably is accidental.
The main reason for the contrasting band structures lies in the
existence of uniform Pd(dmit)2 stacks in the first salt, whereas
the stacks of the second one are built from slipped [Pd(dmit)2]2
diads.
Acknowledgment. This work was sponsored in part by an
EEC Molecular Conductors Network Award (Grant No.
ERB4050PL930085) and a grant from the Conseil Re´gional
Midi-Pyre´ne´es (CCRRDT Grant No 9300690). We thank D.
de Montauzon for assistance in electrochemical studies. C.R.
thanks the Departament d'Ensenyament de la Generalitat de
Catalunya for a predoctoral fellowship. E.C. thanks the CNRS
for granting a sabbatical leave that made the stay at ICMAB
possible.
Conclusion
This work was part of the general research effort4,13,14,23-25
aimed at extending the range of molecular conductors and
superconductors based on transition metal complexes by (i)
designing and using new ligands, (ii) changing the nature of
the metal, and (iii) changing the nature of the counterion in the
derived NIOS compounds.
Supporting Information Available: Figures showing cyclic vol-
tammograms of (PPN)[Ni(dmit)2], (BTP)[Ni(dmit)2], (SMe3)2[Pd-
(dmit)2], (NEt4)[Pd(dddt)2], and (NBu4)[Pt(dtdt)2], single-crystal con-
ductivity of (PPN)[M(dmit)2]z and (BTP)[M(dmit)2]z (M ) Ni, Pd),
and single-crystal conductivity of (SMeyEt3-y)[Ni(dmit)2]z (y ) 0, 1,
3) (Figures S1, S2, and S3). Elemental analyses and IR data for starting
(cation)n[ML2] complexes (L ) dddt2-, dtdt2-, dmit2-; n ) 0, 1, 2; M
) Ni, Pd, Pt) (Table S1), electrocrystallization conditions, conductivity
values, and elemental analyses for [M(dddt)2][M′(dmit)2]x and (cation)-
[M(dmit)2]z compounds with cation ) PPN+, BTP+ (Tables S2 and
S3), electrocrystallization conditions and conductivity values for
(SMeyEt3-y)[M(dmit)2]z compounds (Table S4), additional relevant
parameters of data collections and refinements (Table S5), hydrogen
atomic parameters (Tables S6-S11, anisotropic thermal parameters
(Tables S12-S18), and bond distances and angles (Tables S19-S25)
for compounds 1-7, and cyclic voltammetry data (Tables S26 and S27).
(29 pages). Ordering information is given on any current masthead
page.
Although the dddt2- and dtdt2- ligands were designed and
selected because of their resemblance to the previously suc-
cessfully used dmit2- ligand, no radical anion NIOS compounds
could be obtained by from their complexes, and only radical
cation NIOS compounds may be obtained by using the
complexes of dddt2-. An explanation of this behavior is found
in the compared electrochemical studies of the complexes of
these three ligands.
Thus, the M(dmit)2 complexes remain the best candidate
systems for preparing conducting NIOS compounds, and several
examples are given in this work. Much work remains to be
done to better characterize some of the most interesting prepared
phases, for example, the highly conducting phases (BTP)[Pd-
(dmit)2]z, (PPN)[Ni(dmit)2]z, and (PPN)[Pd(dmit)2]z, by deter-
mining their structures and carrying out further conductivity
measurements, for example, under pressure. The continuation
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