Preparation and characterization of metal complexes with an extended TTF dithiolato ligand, bis(propylenedithiotetrathiafulvalenedithiolato)-nickelate and -cuprate

Article abstract of DOI:10.1039/a704518b

Novel monoanionic nickel and dianionic copper complexes with the extended TTF dithiolato ligand, propylenedithiotetrathiafulvalenedithiolate [ptdt^2- =(S₈C₉H₆)^2-], have been synthesized. Characterization of monoanionic tetraphenylphosphonium and tetramethylammonium salts of Ni(ptdt)₂^- and the dianionic tetraphenylphosphonium salt of Cu(ptdt)₂^2- have been performed, using cyclic voltammetry, electrical resistivity measurements, magnetic susceptibility measurements and X-ray crystal structure determination. The geometries around the Ni atoms are almost square planar. In both Ni complexes, one of the extended ligands of Ni(ptdt)₂^- is overlapping with that of the adjacent anion separated by about half of the unit of the molecule, forming a one-dimensional chain. The adjacent chains are connected by transverse short S...S contacts. Cu(ptdt)₂^2- has a distorted tetrahedral geometry around the Cu atom and the dihedral angle between the planes of the dithiolato ligand is 54.2°. The crystal structures of Ni(ptdt)₂^- and Cu(ptdt)₂^2- complexes show the possibility of novel 2D or 3D intermolecular contacts through ptdt ligands. The complex [Me₄N][Ni(ptdt)₂]·Me₂CO is a semiconductor with a room temperature conductivity of 1.4 × 10^-3 S cm^-1 and activation energy of 9.9 × 10^-2 eV.

Full text of DOI:10.1039/a704518b

J O U R N A L O F
Preparation and characterization of metal complexes
with an extended TTF dithiolato ligand,
bis(propylenedithiotetrathiafulvalenedithiolato)-nickelate
and -cuprate†
C H E M I S T R Y
Mieko Kumasaki, Hisashi Tanaka and Akiko Kobayashi*
Department of Chemistry, Faculty of Science, T he University of T okyo, Hongo, Bunkyo-ku, T okyo
113, Japan
Novel monoanionic nickel and dianionic copper complexes with the extended TTF dithiolato ligand,
propylenedithiotetrathiafulvalenedithiolate [ptdt2−=(S C H )2−], have been synthesized. Characterization of monoanionic
8 9
6
tetraphenylphosphonium and tetramethylammonium salts of Ni(ptdt) − and the dianionic tetraphenylphosphonium salt of
measurements and X-ray crystal structure determination. The geometries around the Ni atoms are almost square planar. In both
2
Cu(ptdt) 2− have been performed, using cyclic voltammetry, electrical resistivity measurements, magnetic susceptibility
2
Ni complexes, one of the extended ligands of Ni(ptdt) − is overlapping with that of the adjacent anion separated by about half of
2
the unit of the molecule, forming a one-dimensional chain. The adjacent chains are connected by transverse short S,S contacts.
Cu(ptdt) 2− has a distorted tetrahedral geometry around the Cu atom and the dihedral angle between the planes of the dithiolato
intermolecular contacts through ptdt ligands. The complex [Me N][Ni(ptdt) ]·Me CO is a semiconductor with a room
2
ligand is 54.2 °. The crystal structures of Ni(ptdt) − and Cu(ptdt) 2− complexes show the possibility of novel 2D or 3D
2
2
4
2
2
temperature conductivity of 1.4×10−3 S cm−1 and activation energy of 9.9×10−2 eV.
In recent investigations of molecular conductors and supercon-
ductors, there is increasing interest in molecules with extended
p-conjugation frameworks.1 This is because such molecules
can stabilize multi-cation states and increase intermolecular
interactions. Furthermore metal complexes with extended p
ligands are expected to open a new field of molecular conduc-
tors owing to the variety of central metal atoms and possible
modifications of the extended p-conjugation ligands. However,
only a few conducting metal complexes with elongated dithi-
olene-type ligands have been prepared.
metal complexes with elongated p-ligands will provide new
types of molecular conducting systems. Here, we report the
preparation of a new ligand, propylenedithiotetrathiafulvalene-
dithiolate (C H S 2−, ptdt2−) and the crystal structures of a
9
6 8
precursor of the ligand ptdt(CH CH CN) , the tetraphenyl-
2
2
2
phosphonium salt of a square-planar Ni complex, (Ph P)-
[Ni(ptdt) ]·1.4Me CO 1, the tetramethylammonium salt of
the Ni complex, (Me N)[Ni(ptdt) ]Me CO 2 and a tetrahedral
Cu complex, (Ph P) [Cu(ptdt) ]·1.2Me CO 3.
4
2
2
4
2
2
2
4
2
2
Recently, Narvor et al. have reported the synthesis, structure
and conductive properties of nickel complexes of tetrathiafulva-
lenedithiolate, which exhibited a fairly high conductivity in the
neutral state.2 However bulky terminal SR (R=alkyl) groups
sticking out from the molecular plane might prevent close
intermolecular S,S contacts. Nakano et al. have prepared
metal complexes of ethylenedithiotetrathiafulvalenedithiolate
(C H S 2−, etdt2−).3 The etdt metal complexes, however, have
Experimental
Synthesis and crystal growth
Reagent-grade tetrahydrofuran was purified and distilled over
sodium–benzophenone prior to use. Methanol was refluxed
over Mg and distilled; other solvents and chemicals were used
as received. Schlenk techniques were used in carrying out
manipulations under argon atmosphere. NMR spectra were
measured on a JEOL JNM-EX 270 Model spectrometer.
Cyclic voltammetry data were recorded by BAS CV-60W. The
ptdt2− ligand was synthesized as shown in Scheme 1.
Initially, we used p-acetoxybenzyl as the protecting group
in cross-coupling to synthesize the unsymmetrical precursor of
ptdt2−. Gemmell et al.4 and Misaki et al.5 reported that their
unsymmetrical TTF derivatives were obtained in high yields
using this protecting group. In our case, however, the cross-
coupling method gave more than five products and our target
molecule was obtained in only 4.6% yield. We then used
cyanoethyl as the protecting group, and succeeded in obtaining
7 in high yield.
8
4 8
poor solubility as is often the case for molecules with extended
p-conjugation, which is unfavorable for obtaining good single
crystals. Thus a crystal structure of an M(etdt) compound
has not been reported. Therefore, an improvement of the
2
solubility seems to be necessary for further development.
In order to increase solubility, we prepared a new ligand
which incorporates an additional methylene group into etdt2−.
One of the important requirements for constituent molecules
of the molecular conductors is good planarity of the molecules.
However in metal complexes with tetrathiafulvalenedithiolate,
the planarity of the whole molecule may be not so important.
The long ligand will be preferably favorable for increasing
overlapping between the molecules. Each of the two tetrathia-
fulvalene moieties joined to the central transition metal atom
will be able to produce S,S networks even if the metal
complex molecule has a twisted conformation. Thus transition
Preparation of 4,5-propylenedithio-1,3-dithiole-2-thione 4.
(Et N) [Zn(dmit) ] (43 g) was dissolved in 200ml of aceto-
4
2
2
nitrile and 26 g of 1,3-dibromopropane was added and the
solution stirred for 2 d at room temperature. The resulting
orange precipitate was filtered off and to the residue dichloro-
methane was added and the solution was filtered. Activated
charcoal (0.2 g) was added to the filtrate and the solution was
† Presented at the 58th Okazaki Conference, Recent Development and
Future Prospects of Molecular Based Conductors, Okazaki, Japan,
7–9 March 1997.
J. Mater. Chem., 1998, 8(2), 301–307
301

S
S
S
S
S
S
S
S
S
S
S
S
Br
Br
[(C2H5)4N]2
S
S
S
Zn
CH3CN
4
[Et4N]2[Zn(dmit)2]
Br
S
S
S
S
S
5
CN
CN
S
S
6
CN
CN
Hg(OAc)2–CHCl3
AcOH
NC
[Et4N]2[Zn(dmit)2]
S
O
CH3CN
S
S
S
+
+
S
S
S
S
S
S
S
S
CN
CN
S–NMe4
P(OEt)3
NMe4OH
MeOH
4 + 6
S–NMe4
S
S
S
S
7
S
S
S
S
S
S
S
S
S
S
S
S
M2+
(NMe4)x
M
S
S
S
S
S
S
8 M = Ni
9 M = Cu
S
S
S
S
S
S
S
S
S
S
cation exchange
(PPh4)m(solvent)n
M
S
S
S
S
1 M = Ni
3 M = Cu
Scheme 1
refluxed for 30 min. The solution was filtered and ethanol was
added. Yellow crystals were obtained from this solution at
−20 °C. Yield 19.6g. {68.7% based on (Et N) [Zn(dmit) ]}.
to −20 °C. Orange yellow needle crystals were obtained. Yield
3.1 g. (60.5% based on 6) (Found: C, 37.48; H, 2.95; N, 5.84; S,
53.30. C H N S requires C, 37.63; H, 2.95; N, 5.85; S, 53.58%).
4
2
2
15 14 2 8
1H NMR(270 MHz, CDCl , ref. TMS) d : 3.08 (4H, t, J=
7.1 Hz), 2.76–2.69 (8H, m), 2.41 (2H, m).
3
H
Preparation of 4,5-bis(2-cyanoethylthio)-1,3-dithiole-2-thione
5. (Et N) [Zn(dmit) ] (10 g) was dissolved in 80 ml of aceto-
4
2
2
nitrile and 7 g of 3-bromopropionitrile was added to the
solution and was refluxed for 1 h. The solution was filtered off
and then concentrated. After adding 125 ml of dichloro-
methane, the solution was washed three times with water.
Then the solution was dried with magnesium sulfate. After
removing the drying agent, ethanol was added at −20 °C.
Brown yellow needle crystals were obtained. Yield 5.6 g.
{66.1% based on (Et N) [Zn(dmit) ]}.
Preparation of 8. The following procedures were performed
under an argon atmosphere. To 101 mg of 7 in a 300 ml flask
was added 22 ml of THF and the solution was cooled to
−78 °C using a dry-ice bath. The tetramethylammonium salts
were obtained by deprotection with 0.2 ml of Me NOH fol-
4
lowed by addition of 20 ml of a methanol solution containing
5 mg of NiCl ·6H O. This solution was stirred overnight and
2
2
then gradually warmed to room temperature. The obtained
precipitate was filtered off and dried in vacuo (1 mmHg) and
obtained as a brown powder.
4
2
2
4,5-Bis(2-cyanoethylthio)-1,3-dithiole-2-one 6. To 4.8 g of 5
and 12.1 g of Hg(CH COO) in a 300 ml flask were added
3
2
160 ml of chroloform–acetic acid (351). The solution was
stirred at room temperature overnight. A white precipitate was
obtained and filtered off using Celite. The filtered solution was
Preparation of 9. The following procedures were performed
under an argon atmosphere. To 101 mg of 7 in a 300 ml flask
was added 22 ml of THF. The solution was then cooled to
−78 °C using a dry-ice bath. The tetramethylammonium salts
washed with water, saturated NaHCO aqueous solution,
water and dried with Na SO . After removing the drying
3
was prepared by deprotection with 0.2 ml of Me NOH followed
2
4
4
agent, the filtrate was concentrated and ethanol was added at
−20 °C. Milky white crystals were obtained. Yield 3.7 g.
(83.7% based on 5).
by addition of
a
20 ml methanol solution of 5 mg of
CuCl ·2H O at −78 °C. This solution was stirred overnight
2
2
and the reaction mixture was warmed gradually to room
temperature. The obtained green precipitate was filtered off
and dried at 1 mmHg pressure.
2,3-Bis (2-cyanoethylthio)-6,7-propylenedithiotetrathiaful-
valene 7. To 4.4 g of 4 and 3.0 g of 6 in a 200 ml flask under an
argon atmosphere was added freshly distilled P(OC H )
Preparation of 1 and 2. Compound 8 and tetraphenylphos-
phonium bromide were placed in separate compartments of
an H-cell under argon. Acetone was poured into the H-cell
which was left to stand undisturbed. After 10 days, red plate
crystals of 1 were obtained. Crystals of 2 were obtained
unexpectedly in the procedure of the electrocrystallization
using a current of 0.1 mA in an H-shaped cell with platinum
2
5 3
(130 ml) under flushing argon. The reaction mixture was then
raised to 110 °C. After reaction for 1 h, the red solution was
cooled to room temperature and a precipitate was obtained at
−20°C. The precipitate was dissolved into dichloromethane and
7 was isolated by dichloromethane silica gel column chromatog-
raphy. The solution was concentrated, ethanol added and cooled
302
J. Mater. Chem., 1998, 8(2), 301–307

electrodes under an argon atmosphere. The crystals were
obtained using 10 mg of 8 and tetramethylammonium bromide
and then adding 20 ml of acetone. Black block crystals were
collected from the bottom of the H-cell after 3 weeks.
the non-hydrogen atoms and refinement was by full-matrix
least-squares methods. The calculated positions of hydrogen
atoms [d(C–H)=0.95 A] were included in the final calculation
˚
except for the solvent molecules. The populations of the solvent
molecules are refined initially and fixed in the final calculation.
Atomic scattering factors were taken from ref. 6. The absolute
configuration of the crystal structure of 7 could not be deter-
mined owing to an insufficient number of Friedel pair reflec-
tions. All calculations were performed using the teXsan
crystallographic software package of the Molecular Structure
Corporation.7 Full crystallographic details excluding structure
factors have been deposited at the Cambridge Crystallographic
Data Centre (CCDC). See Information for Authors, J. Mater.
Chem., 1998, Issue I. Any request to the CCDC for this material
should quote the full literature citation and the reference
number 1145/54.
Preparation of 3. Compound 9 and tetraphenylphosphonium
bromide were placed in separate compartments of an H-cell
under argon. Acetone was poured into the H-cell which was
left to stand undisturbed. After 10 days green plate crystals
were obtained.
Cyclic voltammetry
Cyclic voltammetry (CV) of (Me N) [Cu(ptdt) ] 9 and
(Me N)[Ni(ptdt) ] 8 were carried out in acetonitrile using
4
2
2
4
4
2
(Bu N)ClO as supporting electrolyte at 100 mV s−1 over the
4
potential range −1.8 to +2.0 V. The working and counter
electrode were platinum and the reference electrode was
Ag/Ag+. (Me N) [Cu(ptdt) ] and (Me N)[Ni(ptdt) ] showed
Magnetic susceptibility
4
2
2
4
2
qualitatively similar features, but the latter’s peak intensities
decreased on repeated scanning due to the formation of an
insoluble film of the neutral 151 salt on the electrode.
(Me N) [Cu(ptdt) ] showed one reduction process at −0.73 V
The magnetic susceptibility was measured at a field of 2 T
from 300 to 2 K using a Quantum Design MPMS SQUID
magnetometer.
4
2
2
vs. SCE and two oxidation process at −0.08 and +1.15 V vs.
SCE, while (Me N)[Ni(ptdt) ] showed peaks at −0.45, −0.15,
Electrical resistivity
4
2
Resistivities were measured by a conventional four-probe
method using gold wire (0.02 mm) with gold paint as a contact
in the temperature range 300–77 K.
and +1.20 V. The CV data of these compounds indicate that
the peak at −0.08 V of the Cu complex appears to correspond
to the process Cu(ptdt) 2−Cu(ptdt) − and the peak at
2
2
−0.45 V of the Ni complex corresponds to the process
Ni(ptdt) 2−Ni(ptdt) −; Ni(ptdt) 2− is readily oxidized to
Results and Discussion
2
Ni(ptdt) −.
2
2
2
Crystal structures
Crystal structure determination
2,3-Bis(2-cyanoethylthio)-6,7-propylenedithiotetrathiafulval-
Intensity data were measured on Rigaku AFC-7R, AFC-5R or
AFC-6S automated four-circle diffractometers using graphite
monochromated Mo-Ka radiation at 23 °C. Empirical absorp-
tion corrections were performed. The experimental details and
crystal data are listed in Table 1. The structure were solved by
direct methods. Anisotropic temperature factors were used for
ene5ptdt(CH CH CN) 7. The ptdt(CH CH CN) molecule is
2
2
2
2
2
2
shown in Fig. 1(a) and selected bond lengths are listed in Table 2.
Atoms S(1), S(2), S(3), S(4), C(1) and C(2) lie in a good plane
A while atoms S(3), S(4), S(5), S(6), S(7), S(8), C(3), C(4),
C(5) and C(6) including a tetrathiafulvalene group form a fairly
good plane B. Atoms S(7), S(8), C(5), C(6), C(7), C(8) and
Table 1 Crystal and experimental data
(Me N)[Ni(ptdt) ]·Me CO
(Ph P)[Ni(ptdt) ]·1.4Me CO
(Ph P) [Cu(ptdt) ]·1.2Me CO
ptdt(CH CH CN)
4
2
2
4
2
2
4
2
2
2
2
2
2
formula
C
H
S
NNiO
C
H
S
PNiO
C
H
S
CuP O
C H N S
25 30 16
47.40 44.60 16
1.40
69.60 59.20 16
2
1.20
15 14 2 8
crystal color, habit
crystal system
formula mass
black, block
triclinic
932.18
12.799(1)
13.306(1)
12.539(2)
91.172(9)
108.421(7)
109.482(6)
1890.9(4)
P1
2
1.637
0.30×0.20×0.20
Mo-Ka
AFC 5R
14.21
55.0
9230
red, plate
monoclinic
1190.53
28.567(3)
8.289(6)
25.295(6)
green, block
monoclinic
1553.29
21.420(6)
11.826(4)
29.18(1)
orange, needle
monoclinic
478.77
9.96(3)
6.707(9)
15.08(5)
˚
a/A
˚
b/A
˚
c/A
a/degrees
b/degrees
c/degrees
108.08(1)
91.20(3)
101.0(2)
988(3)
P2
˚
V/A3
space group
5694(3)
C2/c
4
1.389
0.30×0.20×0.20
Mo-Ka
AFC 7R
9.93
55.0
7155
7007
288
v
0.73+0.30tanh
16
7390(3)
P2/c
4
1.396
0.20×0.30×0.10
Mo-Ka
AFC 5R
8.34
9
1
Z
2
1.608
D /g cm−3
radiation
x
dimensions/mm
0.30×0.10×0.60
Mo-Ka
AFC 6S
9.05
55.3
2619
2483
226
v–2h
1.10+0.30tanh
8.0
diffractometer
m/cm−1
total reflections
2h /degrees
max
55.0
18 277
17 814
790
reflections used
parameters refined
scan technique
scan width
8693
397
v–2h
1.57+0.30tanh
12
v
0.73+0.30tanh
16
v scan speed
(degrees min−1)
final shift/error
R, R
0.039, 0.034
0.67
0.34
0.060, 0.058
0.59
0.77
0.065, 0.055
0.06
0.38
0.035, 0.036
0.06
0.24
w
˚
residual d/e A−3
J. Mater. Chem., 1998, 8(2), 301–307
303

Fig. 2 (a) ORTEP drawing of the monoanion Ni(ptdt) − showing the
in (Ph P)[Ni(ptdt) ]·1.4Me CO.
2
atom labelling at the 50% probability level. (b) Side view of Ni(ptdt) −
2
4
2
2
˚
Table 3 Selected bond lengths (A) and angles (degrees)
for (Ph P)[Ni(ptdt) ]·1.4Me CO
4
2
2
Ni(1)MS(1)
Ni(1)MS(2)
S(1)MC(1)
S(2)MC(2)
S(3)MC(1)
S(3)MC(3)
S(4)MC(2)
S(4)MC(3)
S(5)MC(4)
S(5)MC(5)
S(6)MC(4)
2.154(1)
2.167(2)
1.735(7)
1.707(6)
1.765(6)
1.757(7)
1.762(7)
1.773(7)
1.755(7)
1.757(7)
1.765(7)
S(6)MC(6)
S(7)MC(5)
S(7)MC(7)
S(8)MC(6)
S(8)MC(9)
C(1)MC(2)
C(3)MC(4)
C(5)MC(6)
C(7)MC(8)
C(8)MC(9)
1.752(7)
1.736(7)
1.809(8)
1.739(8)
1.783(8)
1.345(9)
1.323(8)
1.36(1)
1.49(1)
1.54(1)
Fig. 1 (a) ORTEP drawing8 of ptdt(CH CH CN) showing the atom
labelling at the 50% probability level. (b) Side view of
ptdt(CH CH CN) .
2
2
2
S(1)MNi(1)MS(1) 180.00
S(1)MNi(1)MS(2)
S(1)MNi(1)MS(2)
S(1)MNi(1)MS(2)
S(1)MNi(1)MS(2)
S(2)MNi(1)MS(2) 180.00
87.07(7)
92.93(7)
92.93(7)
87.07(7)
2
2
2
˚
Table 2 Selected bond lengths (A) for ptdt(CH CH CN)
2
2
2
S(1)MC(1)
S(2)MC(2)
S(3)MC(1)
S(3)MC(3)
S(4)MC(2)
S(4)MC(3)
S(5)MC(4)
S(5)MC(5)
S(6)MC(4)
S(6)MC(6)
1.752(6)
1.761(6)
1.751(6)
1.744(6)
1.753(6)
1.771(6)
1.743(6)
1.752(6)
1.752(6)
1.766(6)
S(7)MC(5)
S(7)MC(7)
S(8)MC(6)
S(8)MC(9)
C(1)MC(2)
C(3)MC(4)
C(5)MC(6)
C(7)MC(8)
C(8)MC(9)
1.738(6)
1.821(8)
1.754(6)
1.847(9)
1.328(8)
1.342(7)
1.310(8)
1.46(1)
and angles of Ni(ptdt) − are similar to those of the analogous
two methyl groups [2.172(5), 2.160(7) A and 93.3(2), 86.7(2) °,
2
compound in which propylene groups are substituted for the
˚
respectively].2 The central C(3)MC(4) bond length is
1.323(8) A, which is shorter than that in 7. The seven-mem-
˚
bered heteroring is flexible and those in ptdt(CH CH CN) 1
and Ni(ptdt) − 2 bend at S(7) and S(8) in the opposite
2
2
2
2
1.50(1)
direction. The crystal structure of 1 [Fig. 3(a)] showed that
one of the ligands of Ni(ptdt) − is overlapping with that of
forming a one-dimensional chain along [110]. The overlapping
2
the adjacent anion separated by the translation 1/2a−1/2b,
C(9) form a seven-membered heteroring. This seven-membered
ring adopts a chair conformation and is tilted from plane B. The
central C(3)MC(4) bond length is 1.342(7) A, which is similar
to that of the CNC bond length in neutral bis(propylenedithio)-
tetrathiafulvalene [1.341(4) A].9 The C(1)MC(2) and C(5)M
C(6) distances are 1.328(8) and 1.310(8) A, respectively, which
mode of Ni(ptdt) − is shown in Fig. 3(b), which shows that
2
˚
˚
˚
are shorter than the central C(3)MC(4). Fig. 1(b) shows that
C(7), C(8) and C(9) show the largest deviation from plane A,
˚
of 4.06, 4.27 and 3.91 A, respectively. The dihedral angle of
planes A and B is 21.25 °.
(Ph P)[Ni(ptdt) ]·1.4Me CO 1. The Ni(ptdt) − anion is
4
shown in Fig. 2(a) and selected bond lengths and angles are
2
2
2
shown in Table 3. The Ni(ptdt) − anion is located on an
2
inversion center. Atoms Ni(1), C(1), C(2), S(1), S(2), S(3)
and S(4) lie on a common plane A while the terminal propyl-
enic group is bent. The mean deviation of the atoms from the
˚
least-squares plane is ca. 0.03 A. Atoms S(7) and S(8) show
˚
the largest deviation from the plane at 2.062 and 1.998 A. The
planarity of the molecule is better than the neutral
ptdt(CH CH CN) molecule [Fig. 2(b)]. Atoms S(5), S(6),
2
2
2
S(7), S(8), C(5) and C(6) form a plane B with the dihedral
angle between planes A and B being 30.13 °. The square-planar
˚
Ni complex shows NiMS distances of 2.154(2) and 2.167(2) A
and SMNiMS angles of 92.93(7) and 87.07(7) °. The distances
Fig. 3(a) Crystal structure of (Ph P)[Ni(ptdt) ]·1.4Me CO. (b)
Overlapping mode of Ni(ptdt) − in (Ph P)[Ni(ptdt) ]·1.4Me CO.
4
2
2
2
4
2
2
304
J. Mater. Chem., 1998, 8(2), 301–307

˚
Table 4 Selected bond lengths (A) and angles (degrees)
for (Me N)[Ni(ptdt) ]·Me CO
the Ni(ptdt) − anion is deviated along the short axis of the
2
˚
molecule. The interplanar distance is ca. 3.25 A on average.
4
2
2
˚
The shortest Ni,Ni distance is 14.87 A while the shortest
Ni(1)MS(1)
Ni(1)MS(2)
Ni(1)MS(9)
Ni(1)MS(10)
S(1)MC(1)
S(2)MC(2)
S(3)MC(1)
S(3)MC(3)
S(4)MC(2)
S(4)MC(3)
S(5)MC(4)
S(5)MC(5)
S(6)MC(4)
S(6)MC(6)
S(7)MC(5)
S(7)MC(7)
S(8)MC(6)
S(8)MC(9)
S(9)MC(10)
S(10)MC(11)
S(11)MC(10)
2.163(1)
2.172(1)
2.174(1)
2.164(1)
1.712(4)
1.717(4)
1.763(4)
1.761(4)
1.767(4)
1.755(4)
1.760(4)
1.765(4)
1.753(4)
1.765(4)
1.739(4)
1.816(5)
1.740(4)
1.806(4)
1.715(4)
1.711(4)
1.759(4)
S(11)MC(12)
S(12)MC(11)
S(12)MC(12)
S(13)MC(13)
S(13)MC(14)
S(14)MC(13)
S(14)MC(15)
S(15)MC(14)
S(15)MC(16)
S(16)MC(15)
S(16)MC(18)
C(1)MC(2)
1.763(4)
1.748(4)
1.767(4)
1.758(4)
1.756(4)
1.745(4)
1.748(4)
1.753(4)
1.815(5)
1.747(4)
1.808(5)
1.358(5)
1.352(5)
1.341(5)
1.511(6)
1.519(6)
1.361(5)
1.332(5)
1.343(5)
1.515(6)
1.519(7)
˚
intermolecular S,S contact is 3.320(3) A [S(1),S(7)], corre-
sponding to the transverse S,S short contact with the neigh-
bouring chain. Along the c-axis, however, no interaction is
expected because the large tetraphenylphosphonium cations
prevent the overlap of anions in this direction. The acetone of
crystallization shows slight evidence of disorder with one of
the CMC bond lengths being a little shorter than the other
˚
[CMC=1.28(2), CNO 1.17(1), CMC 1.57(2) A] and the
angles deviate from 120 ° [134 (1), 112 (1), 104 (1)°]. The
population of the acetone molecule was determined by least-
squares refinement as 0.7. The stereoview of anion arrangement
of (Ph P)[Ni(ptdt) ]·1.4Me CO is shown in Fig. 4.
C(3)MC(4)
C(5)MC(6)
C(7)MC(8)
4
2
2
C(8)MC(9)
(Me N)[Ni(ptdt) ]·Me CO 2. The Ni(ptdt) − anion is
C(10)MC(11)
C(12)MC(13)
C(14)MC(15)
C(16)MC(17)
C(17)MC(18)
4
2
2
2
shown in Fig. 5 and selected bond lengths and angles are listed
in Table 4. Atoms Ni(1), C(1), C(2), S(1), S(2), S(3), S(4),
C(10), C(11), S(9), S(10), S(11) and S(12) are in a common
plane and the terminal propylenic group is bent. The mean
˚
S(1)MNi(1)MS(2)
93.11(4)
S(1)MNi(1)MS(9) 175.84(6)
S(1)MNi(1)MS(10) 85.52(4)
S(2)MNi(1)MS(9)
88.72(4)
S(2)MNi(1)MS(10) 176.43(6)
S(9)MNi(1)MS(10) 92.86(4)
deviation of atoms from the least-squares plane is ca. 0.07 A.
Atoms S(7), S(8) S(15) and S(16) show the largest deviation
˚
from the plane at 1.309, 1.390, 1.202 and 1.512 A, respectively.
Thus the planarity of the molecule is fairly high. The almost
square-planar Ni complex shows NiMS distance of 2.163(1),
˚
crystal structure of 2 is shown in Fig. 6(a). Fig. 6(b) shows that
one of the ligands of Ni(ptdt) − is overlapping with that of an
molecule, forming a one-dimensional chain along [101]. The
2.172(1), 2.174(1) and 2.164(1) A while the SMNiMS angles
within the five-membered ring are 93.11(4) and 92.86(4) ° the
remainder are 85.52(4) and 88.72(4) °, respectively. The
dihedral angle between the planes S(1)NiS(2) and S(3)NiS(4)
is 4.86 °. The central CNC bond lengths, C(3)MC(4) and
2
adjacent anion separated by about half of the unit of the
overlapping mode of Ni(ptdt) − is ring-over-bond type and
chain of 2 is larger than that in 1. The shortest intermolecular
2
˚
the interplanar distance is 3.30 A. The overlap in the anion
˚
C(12)MC(13) are 1.352(5) and 1.332(5) A, respectively. The
˚
S,S distance is 3.525(2) A [S(7),S(15)], shown in Fig. 6(a)
as dotted lines. Along the [011] direction, the shortest trans-
˚
verse S,S and Ni,Ni distances are 3.559(2) A [S(8),S(13)]
and 6.562(1) A, respectively. The characteristic feature of stack-
˚
ing is short S,S contacts between the neighbouring chains
along the [201] direction, which was not observed for 1 owing
to the large tetraphenylphosphonium cation. The interaction
is expected because the small tetramethylammonium cation
does not prevent contacts of the anions in this direction. The
acetone of crystallization is not disordered.
Fig. 4 Stereoview
[Ni(ptdt) ]·1.4Me CO.
of
the
crystal
structure
of
(Ph P)-
4
2
2
Fig. 5 ORTEP drawing of the monoanion Ni(ptdt) − showing the
Fig. 6 (a) Crystal structure of (Me N)[Ni(ptdt) ]·Me CO. (b)
Overlapping mode of Ni(ptdt) − in (Me N)[Ni(ptdt) ]·Me CO.
2
4
4
2
2
2
2
atom labelling at the 50% probability level
2
J. Mater. Chem., 1998, 8(2), 301–307
305

(Ph P) [Cu(ptdt) ]·1.2Me CO 3. The Cu(ptdt) 2− anion is
4
shown in Fig. 7 and selected bond lengths and angles are listed
2
2
2
2
in Table 5. The terminal propylenic group of Cu(ptdt) 2− is
2
bent as found for the Ni complex. A distorted tetrahedral
geometry is observed around the Cu atom with CuMS distances
˚
of 2.279(4), 2.273(4), 2.282(4) and 2.265(4) A and SMCuMS
angles of 93.6(1), 93.2(1), 140.3(2) and 142.0(2) °. The dihedral
angle between the planes S(1)CuS(2) and S(9)CuS(10) is 54.2 °.
The central CNC bond lengths C(3)MC(4) and C(12)MC(13)
˚
are 1.35(1) and 1.35(2) A, respectively. The geometry around
the Cu atom is almost the same as in [epy] [Cu(dmit) ]
2
2
(epy=N-ethylpyridinium; dmit=4,5-dimercapto-1,3-dithiole-
2-thione).10 In this case the dihedral angle is 57.3 °. The crystal
structure is shown in Fig. 8 and the schematic stacking pattern
of 3 is shown in Fig. 9. The anions form a one-dimensional
chain along the c-direction with both ligands, which overlap in
ring-over-bond type with those of adjacent anions. The
˚
interplanar distance is ca. 3.39 A and the Cu,Cu distance is
˚
˚
14.78 A. The shortest intermolecular S,S distance is 3.582(7) A
[S(16),S(16)], which correspond to short transverse contacts
between adjacent chains. The large tetraphenylphosphonium
cations prevent overlapping along the b direction. The p-
conjugated systems of the ptdt ligand are large enough to form
conduction pathways in the crystal. In the case of
[epy] [Cu(dmit) ], owing to the small size of the ligand, the
2
2
stacking of Cu(dmit) is only via one side of the ligand, which
prevents formation of a good conduction pathway. The next
2
step for the development of new types of molecular conductors
may be oxidation of the complexes.
Magnetic susceptibilities
The temperature dependence of the magnetic susceptibility of
(Me N) [Cu(ptdt) ] within the temperature range 2–300 K
4
2
2
Fig. 8 (a) Crystal structure of (Ph P) [Cu(ptdt) ]·1.2Me CO. (b)
Stereoview of (Ph P) [Cu(ptdt) ]·1.2Me CO.
4
2
2
2
2
4
2
2
Fig. 7 ORTEP drawing of the dianion Cu(ptdt) 2− showing the atom
2
labelling at the 50% probability level
˚
Table 5 Selected bond lengths (A) and angles (degrees)
for (Ph P) [Cu(ptdt) ]·1.2Me CO
4
2
2
2
Cu(1)MS(1)
Cu(1)MS(2)
Cu(1)MS(9)
Cu(1)MS(10)
S(1)MC(1)
S(2)MC(2)
S(3)MC(1)
S(3)MC(3)
S(4)MC(2)
S(4)MC(3)
S(5)MC(4)
S(5)MC(5)
S(6)MC(4)
S(6)MC(6)
S(7)MC(5)
S(7)MC(7)
S(8)MC(6)
S(8)MC(9)
S(9)MC(10)
S(10)MC(11)
S(11)MC(10)
2.279(4)
2.273(4)
2.282(4)
2.265(4)
1.73(1)
1.74(1)
1.77(1)
1.76(1)
1.75(1)
1.75(1)
1.73(1)
1.75(1)
1.76(1)
1.76(1)
1.76(1)
1.81(2)
1.72(1)
1.84(1)
1.74(1)
1.72(1)
1.76(1)
S(11)MC(12)
S(12)MC(11)
S(12)MC(12)
S(13)MC(13)
S(13)MC(14)
S(14)MC(13)
S(14)MC(15)
S(15)MC(14)
S(15)MC(16)
S(16)MC(15)
S(16)MC(18)
C(1)MC(2)
1.74(1)
1.78(1)
1.74(1)
1.77(1)
1.79(1)
1.76(1)
1.74(1)
1.75(1)
1.81(1)
1.72(1)
1.78(1)
1.34(2)
1.35(1)
1.35(2)
1.50(2)
1.48(2)
1.34(2)
1.35(2)
1.35(2)
1.53(2)
1.51(2)
Fig. 9 Schematic molecular arrangement and overlapping mode of
(Ph P) [Cu(ptdt) ]·1.2Me CO
4
2
2
2
obeys Curie behavior, indicating non-interacting spins for
(Me N) [Cu(ptdt) ]. The diamagnetic component of the mag-
4
2
2
netic susceptibility was estimated by use of Pascal law to be
−4.9×10−4 emu mol−1.11 The room temperature magnetic
susceptibility of 9.8×10−4 emu mol−1 suggests 0.8 spins per
molecule, which is consistent with the presence of Cu2+.
C(3)MC(4)
C(5)MC(6)
C(7)MC(8)
C(8)MC(9)
C(10)MC(11)
C(12)MC(13)
C(14)MC(15)
C(17)MC(18)
C(16)MC(17)
Electrical resistivities
The temperature dependence of the resistivity of
(Me N)[Ni(ptdt) ]·Me CO was measured by usual four-probe
4
2
2
S(1)MCu(1)MS(2)
S(1)MCu(1)MS(9) 101.6(1)
S(1)MCu(1)MS(10) 140.3(2)
93.6(1)
S(2)MCu(1)MS(9) 142.0(2)
S(2)MCu(1)MS(10) 96.9(1)
S(9)MCu(1)MS(10) 93.2(1)
method and was semiconducting (Fig. 10). The room tempera-
ture conductivity is 1.4×10−3 S cm−1 and the activation
energy is 9.9×10−2 eV.
306
J. Mater. Chem., 1998, 8(2), 301–307

A. Sato for her help in magnetic susceptibility measurements.
This work was partly supported by Grant-in Aid for
Fundamental Research on ‘New Series of BETS
Superconductors with Mixed Halide Gallium Anions’.
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2
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Fig. 10 Temperature dependence of the electrical resistivity of
(Me N)[Ni(ptdt) ]·Me CO
4
2
2
Conclusion
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structures of 1, 2 and 3 show possibility of novel 2D or 3D
intermolecular contacts through ptdt ligands in place of ‘span-
10 G. Matsubayashi, K. Takahashi and T. Takano, J. Chem. Soc.,
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11 L andolt-Bornstein
Zahlenwerte
und
Funktionen
aus
¨
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2
12 A. Kobayashi, T. Naito and H. Kobayashi, Phys. Rev. B., 1995,
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transition metal complexes.12–15 Moreover, a new molecular
conductor with p–d interactions will be expected if a magnetic
transition metal atom is incorporated.16 In order to meet
requirement (2), further experiments are required. Very recently
black crystals of fairly conducting neutral Ni(ptdt) have been
obtained by electrocrystallization with a room temperature
2
conductivity of 2.1 S cm−1 and an activation energy of 0.11 eV.
The conductivity is significantly higher than values normally
observed for other neutral complexes such as dithiolenes
(<10−3 S cm−1) or TTF dithiolenes (<10−1 S cm−1).2
We thank Mr. H. Fujiwara and Miss E. Arai of the Institute
for Molecular Science for their valuable discussions and Miss
Paper 7/04518B; Received 26th June, 1997
J. Mater. Chem., 1998, 8(2), 301–307
307