Tetraphenylphosphonium bis(2-thioxo-1,3-dithiole-4,5-dithiolato)- aurate(III) acetone solvate and ethyltriphenylphosphonium bis(2-thioxo-1,3- dithiole-4,5-dithiolato)aurate(III)

Article abstract of DOI:10.1107/S010827010706074X

In the two title complexes, (C₂₄H₂₀P)[Au(C ₃S₅)₂]-C₃H₆O, (I), and (C₂₀H₂₀P)[Au(C₃S₅)₂], (II), the Au^III atoms exhibit square-planar coordinations involving four S atoms from two 2-thioxo-1,3-dithiole-4,5-dithiolate (dmit) ligands. The Au-S bond lengths, ranging from 2.3057 (8) to 2.3233 (7) A in (I) and from 2.3119 (8) to 2.3291 (10) A in (II), are slightly smaller than the sum of the single-bond covalent radii. In (I), there are two halves of independent Ph₄P⁺ cations, in which the two P atoms lie on twofold rotation axis sites. The Ph₄P⁺ cations and [Au(C ₃S₅)₂]^- anions are interspersed as columns in the packing. Layers composed of Ph₄P⁺ and [Au(C₃S₅)₂]^- are separated by layers of acetone molecules. In (II), the [Au(C₃S₅) ₂]^- anions and EtPh₃P⁺ counter-cations form a layered arrangement, and the [Au(C₃S ₅)₂]^- anions form discrete pairs with a long intermolecular Au...S interaction for each Au atom in the crystal structure.

Full text of DOI:10.1107/S010827010706074X

metal-organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
response time, together with good physicochemical properties,
such as environmental stability and processability (Kuang et
al., 2003).
ISSN 0108-2701
Tetraphenylphosphonium bis(2-
thioxo-1,3-dithiole-4,5-dithiolato)-
aurate(III) acetone solvate and ethyl-
triphenylphosphonium bis(2-thioxo-
1,3-dithiole-4,5-dithiolato)aurate(III)
Xin-Qiang Wang,a* Wen-Tao Yu,a Dong Xu,a Jian-Dong
Fan,a Guang-Hui Zhanga and Quan Renb
aState Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong
University, Jinan 250100, People's Republic of China, and bDepartment of Optics,
School of Information Science and Engineering, Shandong University, Jinan 250100,
People's Republic of China
For nearly three decades, the synthesis and characterization
of 2-thioxo-1,3-dithiole-4,5-dithiolate (dmit) complexes and
related analogues have been paid great attention (Steimeck &
Kirmse, 1979). As special ꢃ-electron conjugated systems, dmit
and related ligands have been used as building units for
electrical conductors and superconductors (Svenstrup &
Becher, 1995; Cassoux, 1999; Pullen & Olk, 1999; Robertson &
Cronin, 2002). The ꢃ-electron delocalization in conjugated
systems can also contribute to an ultrafast optical response
capability and large TONLO effects (Coe, 2004). Recently,
many dmit complexes have been reported as possessing good
TONLO properties (Wang et al., 1999; Liu et al., 2002). In our
previous studies, the TONLO properties of a series of such
complexes were reported. The results showed that they
possess large TONLO properties with sub-picosecond
response times (Yang et al., 2005; Sun et al., 2006). Along with
this research, Au±dmit complexes (Li et al., 2005, 2006) have
been found to possess large n2 and nearly zero absorption with
Correspondence e-mail: xqwang@sdu.edu.cn
Received 21 September 2007
Accepted 19 November 2007
Online 14 December 2007
In the two title complexes, (C24H20P)[Au(C3S5)2]ÁC3H6O, (I),
and (C20H20P)[Au(C3S5)2], (II), the AuIII atoms exhibit
square-planar coordinations involving four S atoms from
two 2-thioxo-1,3-dithiole-4,5-dithiolate (dmit) ligands. The
Ê
AuÐS bond lengths, ranging from 2.3057 (8) to 2.3233 (7) A
Ê
in (I) and from 2.3119 (8) to 2.3291 (10) A in (II), are slightly
smaller than the sum of the single-bond covalent radii. In (I),
there are two halves of independent Ph4P+ cations, in which
the two P atoms lie on twofold rotation axis sites. The Ph4P+
cations and [Au(C3S5)2] anions are interspersed as columns
in the packing. Layers composed of Ph4P+ and [Au(C3S5)2]
are separated by layers of acetone molecules. In (II), the
[Au(C3S5)2] anions and EtPh3P+ counter-cations form a
layered arrangement, and the [Au(C3S5)2] anions form
discrete pairs with a long intermolecular AuÁ Á ÁS interaction
for each Au atom in the crystal structure.
Comment
The third-order nonlinear optical (TONLO) response is very
important in all-optical switching, signal processing and
ultrafast optical communications (Sutherland, 1996). For the
realisation of all-optical switching devices, the material
requirements which have to be met are W >> 1 and T << 1.
These two ®gures of merit are de®ned as W = n2I/(ꢀꢁ) and T =
ꢂꢁ/n2, where n2 is the nonlinear refractive index, ꢀ is the linear
absorption coef®cient, ꢂ is the nonlinear absorption coef®-
cient, ꢁ is the wavelength and I is the light irradiance.
Furthermore, ultrafast response times are required for the
nonlinear processes involved. Therefore, to be practically
useful for all-optical switching, materials should have a large
n2 at the operating wavelength, small ꢀ and ꢂ and an ultrafast
Figure 1
The molecular structure of (I), showing the atom-numbering scheme.
Displacement ellipsoids are drawn at the 50% probability level. H atoms
have been omitted for clarity. There are two halves of independent
tetraphenylphosphonium cations where the two P atoms lie on twofold
rotation axis sites.
m46 # 2008 International Union of Crystallography
DOI: 10.1107/S010827010706074X
Acta Cryst. (2008). C64, m46±m49

metal-organic compounds
good ®gures of merit, W and T, for all-optical switching
applications at 1064 nm. Therefore, they are potential candi-
dates for all-optical switching device applications. To continue
this work, the preparation and structural characterization of
the two title compounds, (C24H20P)[Au(C3S5)2]ÁC3H6O, (I),
and (C20H20P)[Au(C3S5)2], (II), are reported here.
The two structures show similarities with and differences
from each other and the previously reported crystal structures
of 18 related Au±dmit complexes in the Cambridge Structural
Database (CSD; Version 5.38 of May 2007; Allen, 2002). The
similarities are that in all these crystal structures, dmit exhibits
its typical behaviour as a bidentate ligand and the Au3+ ion is
coordinated by four S atoms from two dmit molecules in an
almost square-planar geometry; the four S atoms are planar,
with a slight deviation of the Au atom therefrom, and all of
them have a slight Td distortion. Like the previously reported
An obvious difference between these 20 compounds lies in
the type of [Au(C3S5)2] anion. There is one type of
[Au(C3S5)2] anion in some of these complexes, with large
counter-cations (Miura et al., 2004; Li et al., 2006), and
compounds (I) and (II) belong to this class. In other
complexes, there are two kinds of crystallographically inde-
pendent [Au(C3S5)2] anions in another type of [Au(C3S5)2]
anion (Matsubayashi & Yokozawa, 1990; Li et al., 2005), with
small counter-cations. The counter-cations and their orienta-
tions with respect to the [Au(C3S5)2] anions are different in
these crystal structures. In (I), there are two halves of inde-
pendent (C24H20P)+ cations, in which the two P atoms lie on
twofold rotation axis sites. The (C24H20P)+ cations and
[Au(C3S5)2] anions are interspersed as columns in the
packing. Layers composed of (C24H20P)+ and [Au(C3S5)2] are
separated by layers of acetone. In (II), there are layers of
(C21H22P)+ cations and of [Au(C3S5)2] anions, and the
[Au(C3S5)2] anions form discrete pairs with a long inter-
molecular AuÁ Á ÁS interaction for each Au atom in the crystal
structure.
All the data show that the two [Au(C3S5)2] ring systems in
the title compounds have a high degree of electron delocali-
zation. The most striking physical characteristic of these two
crystal structures is the extended electronically delocalized
core, comprising the central Au3+ ion, four S atoms and the
adjacent C C units in the quasi-square plane. It has been
shown that when Au3+ takes the place of group 12 metal ions
(Zn2+, Cd2+ and Hg2+), electron delocalization is enhanced (Li
et al., 2003). This is due to the un®lled d electron shell of Au3+,
which allows the possibility of low-energy charge-transfer
transitions and is an important contribution to optical nonli-
nearity. In particular, the 3p orbitals of S and 3d orbitals of
Au3+ can overlap to form a highly delocalized system. This
delocalization will greatly enhance hyperpolarizability and
nonlinear susceptibility and lead to large TONLO properties.
The TONLO properties of these two compounds were
measured by the Z-scan technique (Sheik-Bahae et al., 1989,
1990), in mM solutions of both acetone and acetonitrile at
1064 nm. These revealed that their nonlinear refractive indices
were superior to that of CS2.
Ê
complexes, the AuÐS bond lengths [2.3057 (8)±2.3233 (7) A
Ê
for (I) and 2.3119 (8)±2.3291 (10) A for (II)] are slightly
Ê
smaller than the sum of the single-bond covalent radii (1.36 A;
Pauling, 1960). The SÐAuÐS bite angles [87.20 (3)±91.76 (3)ꢀ
for (I) and 86.97 (3)±91.49 (3)ꢀ for (II)] are almost nominal
right angles and the trans SÐAuÐS angles [176.97 (3) and
177.20 (3)ꢀ for (I), and 178.22 (3) and 178.40 (3)ꢀ for (II)] are
very close to 180ꢀ. The C S double bond is much longer than
Ê
the typical C S bond length (1.599 A; Allen et al., 1987). The
Ê
other CÐS bonds [1.723 (4)±1.747 (3) A for (I) and 1.728 (3)±
Ê
1.751 (3) A for (II)] are shorter than the typical CÐS single
Ê
bond (1.819 A; Allen et al., 1987) and are essentially single
bonds with some double-bond character. The two C C bond
Ê
lengths of the dmit ion [1.345 (4) and 1.340 (4) A for (I), and
Ê
1.336 (5) and 1.340 (5) A for (II)] are very close to the
Ê
corresponding double-bond value of 1.341 A (Allen et al.,
1987).
Experimental
For the preparation of (I), 4,5-bis(furoylsulfanyl)-1,3-dithiole-2-
thione (1.211 g) (Wang et al., 2005) was suspended in methanol
(15 ml). Under a nitrogen atmosphere, a sodium methoxide solution
obtained from Na (0.145 g) in methanol (15 ml) was added to the
above-mentioned mixture at room temperature to give a dark-red
solution. To this solution, separate solutions of NaAuCl4Á2H2O
(0.597 g) dissolved in methanol (5 ml) and C24H20PBr (0.659 g) in
methanol (5 ml) were added consecutively with stirring at room
temperature. The reaction mixture was stirred for about 30 min. The
product was collected by ®ltration and washed with methanol to
afford a dark-brown precipitate of (C24H20P)[Au(C3S5)2]. An acetone
solution of the product was left standing at room temperature, and
brown crystals of the solvate, (I), suitable for structure determination
were obtained. Electronic absorption (Hitachi model U-3500
recording spectrophotometer, nm): 339 and 347 (ꢃ±ꢃ* transition of
the dmit ligand), 466 (Au S charge-transfer transition).
Figure 2
The molecular structure of (II), showing the atom-numbering scheme.
Displacement ellipsoids are drawn at the 30% probability level. H atoms
have been omitted for clarity.
ꢁ
Acta Cryst. (2008). C64, m46±m49
Wang et al.
(C24H20P)[Au(C3S5)2]ÁC3H6O and (C20H20P)[Au(C3S5)2] m47

metal-organic compounds
Data collection
For the preparation of (II), 4,5-bis(furoylsulfanyl)-1,3-dithiole-2-
thione (1.211 g) was suspended in methanol (15 ml). Under a nitro-
gen atmosphere, a sodium methoxide solution obtained from Na
(0.145 g) in methanol (15 ml) was added to the above-mentioned
mixture at room temperature to give a dark-red solution. To this
solution, separate solutions of NaAuCl4Á2H2O (0.597 g) dissolved in
methanol (5 ml) and C24H20PBr (0.584 g) in methanol (5 ml) were
added consecutively with stirring at room temperature. The reaction
mixture was stirred for about 30 min. The product was collected by
®ltration and washed with methanol to afford a dark-brown preci-
pitate of (II). An acetone solution of (II) was left standing at room
temperature, and brown crystals of (II) suitable for structure deter-
mination were obtained. Electronic absorption (Hitachi model U-
3500 recording spectrophotometer, nm): 316 and 367 (ꢃ±ꢃ* transition
of the dmit ligand), 446 (Au S charge-transfer transition).
Bruker APEXII CCD area-detector
diffractometer
Absorption correction: multi-scan
(APEX2; Bruker, 2005)
Tmin = 0.361, Tmax = 0.536
(expected range = 0.336±0.499)
22548 measured re¯ections
7292 independent re¯ections
5381 re¯ections with I > 2ꢅ(I)
Rint = 0.027
Re®nement
R[F2 > 2ꢅ(F2)] = 0.027
wR(F2) = 0.057
S = 1.01
344 parameters
H-atom parameters constrained
3
Ê
Áꢆmax = 0.80 e A
3
Ê
0.27 e A
7292 re¯ections
Áꢆmin
=
Table 2
Selected geometric parameters (A, ) for (II).
ꢀ
Ê
Compound (I)
Au1ÐS4
Au1ÐS6
Au1ÐS7
Au1ÐS5
C1ÐS1
C1ÐS3
C1ÐS2
C2ÐC3
C2ÐS2
C2ÐS4
2.3119 (8)
2.3215 (10)
2.3215 (8)
2.3291 (10)
1.637 (3)
1.728 (3)
1.728 (4)
1.336 (5)
1.739 (3)
1.740 (4)
C3ÐS3
C3ÐS5
C4ÐC5
C4ÐS6
C4ÐS8
C5ÐS9
C5ÐS7
C6ÐS10
C6ÐS8
C6ÐS9
1.743 (3)
1.747 (3)
1.340 (5)
1.741 (3)
1.751 (3)
1.743 (3)
1.743 (4)
1.634 (3)
1.731 (4)
1.741 (4)
Crystal data
3
Ê
(C24H20P)[Au(C3S5)2]ÁC3H6O
V = 3795.78 (18) A
Z = 4
Mr = 987.07
Monoclinic, P2=c
Mo Kꢀ radiation
1
Ê
a = 24.4198 (7) A
ꢄ = 4.50 mm
T = 296 (2) K
Ê
b = 7.4511 (2) A
Ê
c = 23.1654 (6) A
ꢂ = 115.7720 (10)ꢀ
0.24 Â 0.23 Â 0.15 mm
Data collection
S4ÐAu1ÐS6
S4ÐAu1ÐS7
S6ÐAu1ÐS7
86.97 (3)
178.22 (3)
91.49 (3)
S4ÐAu1ÐS5
S6ÐAu1ÐS5
S7ÐAu1ÐS5
91.43 (3)
178.40 (3)
90.11 (3)
Bruker APEXII CCD area-detector
diffractometer
Absorption correction: multi-scan
(APEX2; Bruker, 2005)
Tmin = 0.379, Tmax = 0.508
33785 measured re¯ections
8724 independent re¯ections
7545 re¯ections with I > 2ꢅ(I)
Rint = 0.024
Re®nement
R[F2 > 2ꢅ(F2)] = 0.023
wR(F2) = 0.054
S = 1.03
8724 re¯ections
419 parameters
14 restraints
H-atom parameters constrained
For compound (I), all H atoms were placed in geometrically
calculated positions and re®ned using a riding model, with CÐH =
Ê
0.93 (for CH groups) or 0.96 A (for CH3 groups), and with Uiso(H) =
3
Ê
Áꢆmax = 0.62 e A
3
Ê
0.44 e A
Áꢆmin
=
1.2Ueq(C) or 1.5Ueq(methyl C). Although atoms S1 and S10 had large
anisotropic parameters, no suitable disorder model could be found.
Their Uij components were restrained to isotropic behaviour. The
three C atoms of the acetone molecule were also disordered and no
treatment could be applied. The C32ÐC33 and C31ÐC32 distances
were restrained to reasonable values. Since the re¯ections 100 and
302 were obscured by the beam stop, Fo2 is much less than Fc2 in these
re¯ections. They were omitted in the ®nal re®nement.
Table 1
Selected geometric parameters (A, ) for (I).
ꢀ
Ê
Au1ÐS7
Au1ÐS4
Au1ÐS5
Au1ÐS6
C1ÐS1
C1ÐS2
C1ÐS3
C2ÐC3
C2ÐS4
C2ÐS2
2.3057 (8)
2.3166 (7)
2.3191 (7)
2.3233 (7)
1.645 (3)
1.723 (4)
1.730 (4)
1.345 (4)
1.742 (3)
1.747 (3)
C3ÐS5
C3ÐS3
C4ÐC5
C4ÐS8
C4ÐS6
C5ÐS9
C5ÐS7
C6ÐS10
C6ÐS9
C6ÐS8
1.739 (3)
1.743 (3)
1.340 (4)
1.745 (3)
1.746 (3)
1.736 (3)
1.744 (3)
1.639 (4)
1.725 (4)
1.729 (4)
For compound (II), all H atoms were placed in geometrically
calculated positions and re®ned using a riding model, with CÐH =
Ê
0.93 (for CH groups) or 0.96 A (for CH3 groups), and with Uiso(H) =
1.2Ueq(C) or 1.5Ueq(methyl C).
For both compounds, data collection: APEX2 (Bruker, 2005); cell
re®nement: APEX2; data reduction: APEX2; program(s) used to
solve structure: SIR97 (Altomare et al., 1999); program(s) used to
re®ne structure: SHELXL97 (Sheldrick, 1997); molecular graphics:
SHELXTL (Bruker, 1997); software used to prepare material for
publication: WinGX (Farrugia, 1999).
S7ÐAu1ÐS4
S7ÐAu1ÐS5
S4ÐAu1ÐS5
177.20 (3)
87.20 (3)
91.76 (3)
S7ÐAu1ÐS6
S4ÐAu1ÐS6
S5ÐAu1ÐS6
91.48 (3)
89.68 (3)
176.97 (3)
Compound (II)
Crystal data
3
Ê
(C20H20P)[Au(C3S5)2]
Mr = 880.96
V = 3179.99 (6) A
Z = 4
This work was supported by the National Natural Science
Foundation of China (grant Nos. 60476020, 50772059,
60778037, 60608010 and 50672049) and the Foundation for
Authors of National Excellent Doctoral Dissertations of
China (grant No. 200539).
Monoclinic, P21=n
Mo Kꢀ radiation
ꢄ = 5.35 mm
T = 296 (2) K
0.24 Â 0.17 Â 0.13 mm
1
Ê
a = 17.3058 (2) A
Ê
b = 9.93060 (10) A
Ê
c = 19.0668 (2) A
ꢂ = 103.9590 (10)ꢀ
ꢁ
m48 Wang et al. (C24H20P)[Au(C3S5)2]ÁC3H6O and (C20H20P)[Au(C3S5)2]
Acta Cryst. (2008). C64, m46±m49

metal-organic compounds
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Acta Cryst. (2008). C64, m46±m49
Wang et al.
(C24H20P)[Au(C3S5)2]ÁC3H6O and (C20H20P)[Au(C3S5)2] m49