Synthesis, X-ray molecular structure analysis, and study on ligand scrambling reactions of new thiolatogold(I) complexes with various phosphines

Article abstract of DOI:10.1016/S0020-1693(00)00353-4

Treatment of Au(PPh₃)Cl, (AuCl)₂(trans-dpen) and (AuCl)₂(dppfe) with Sn(SPh)(n-Bu)₃ and/or PhSH/KOH affords Au(PPh₃)(SPh) (1), (AuSPh)₂(μ-trans-dpen) (2), (AuSPh)2(μ-dppfe) (3), (AuSPh)(μ-t

Full text of DOI:10.1016/S0020-1693(00)00353-4

www.elsevier.nl/locate/ica
Inorganica Chimica Acta 312 (2001) 100–110
Synthesis, X-ray molecular structure analysis, and study on ligand
scrambling reactions of new thiolatogold(I) complexes with various
phosphines
Satoru Onaka a,*, Yoshitaka Katsukawa b, Michito Shiotsuka c, Osamu Kanegawa a,
Masahiro Yamashita b,1
a Department of En6ironmental Technology, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku,
Nagoya 466-8555, Japan
b Di6ision of Informatics for Science, Graduate School of Human Informatics and PRESTO (JST), Nagoya Uni6ersity, Chikusa-ku,
Nagoya 464-8601, Japan
c Department of Systems Management and Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
Received 15 July 2000; accepted 11 October 2000
Abstract
Treatment of Au(PPh3)Cl, (AuCl)2(trans-dpen) and (AuCl)2(dppfe) with Sn(SPh)(n-Bu)3 and/or PhSH/KOH affords
Au(PPh3)(SPh) (1), (AuSPh)2(v-trans-dpen) (2), (AuSPh)2(v-dppfe) (3), (AuSPh)(v-trans-dpen)(AuCl) (4), and (AuSPh)-
1
(v-dppfe)(AuCl) (5) in good yields. All these thiophenolates are characterized by single crystal X-ray analysis, H and 31P NMR
spectroscopy. 1 forms tetramer through Au···Au interaction and p–p interaction between the phenyl group in SPh and one of the
phenyl groups in PPh3 in the solid state. An infinite chain structure is formed for 2 through intermolecular aurophilicity and these
chains are connected by partial overlap (p–p interaction) of neighboring phenyl groups in SPh to give two-dimensional networks
in the solid state. Similar infinite chains are formed through aurophilicity, but two-dimensional networks are not formed for 4 in
1
the solid state. No multidimensional structure is formed for 3 and 5 in the solid state. H and 31P NMR spectroscopy of CDC13
solutions of 2, 3, 4, and 5 has revealed that rapid ligand scrambling takes place for 4 and 5. © 2001 Elsevier Science B.V. All
rights reserved.
Keywords: Thiolatogold(I) complexes; Au···Au interaction; Infinite chain structures; Ligand scrambling
factory understanding of the structures and bonding of
these thiolatogold nanoparticles, nano-clusters and sur-
1. Introduction
face chemistry, it appears that the systematic study of
There is a continuing interest in the coordination
the chemistry of simple thiolatogold(I) complexes is
chemistry of thiolatogold(I) complexes for several rea-
inevitable. However, to our surprise, there has not been
sons. Among these are the relevance to biological sys-
enough exploration for targeting this field of chemistry
tems especially to drugs [1–7], the usage of the gold
[18,19]. Another interesting feature of the thio-
complexes as lubrication additives [8,9], and the appli-
latogold(I) complexes is that they will provide an excel-
cation to supramolecular chemistry [10,11]. Applica-
lent opportunity for inducing the Au···Au interaction
tions for thiolatogold complexes have surged in the
(aurophilicity) in the solid [20], because recent theoreti-
fields of nanoparticles, nanostructured films, modem
cal studies by Pyykko¨ et al. have suggested that the
electronics, and opto-electonics [12–17]. For the satis-
aurophilic interaction is augmented by introducing a
SR (thiolate) group to a gold(I) complex [21]. Thus
* Corresponding author. Fax: +81-52-7355160.
supramolecular chemistry and/or the design of extended
solid state structural chemistry have been burgeoning
for the past decade with the aid of the aurophilic
E-mail address: onklustr@ks.kyy.nitech.ac.jp (S. Onaka).
1 Present address: Department of Chemistry, Graduate School of
Science, Tokyo Metropolitan University, Tokyo, Japan.
0020-1693/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0020-1693(00)00353-4

S. Onaka et al. / Inorganica Chimica Acta 312 (2001) 100–110
101
interaction [21–28]. In most of these studies, only the
force of the aurophilic interaction has been used to
construct multidimensional arrays in solid states. How-
ever, Schmidbaur et al. has recently successfully assem-
bled the L-Au-X units into supramolecular arrays in
the solid-state by collaborating two weak interactions,
that is, aurophilic interaction and hydrogen bonding
[23]. We have imagined that the collaboration of similar
weak interactions such as p–p interaction with au-
rophilic interaction may also bring an extended solid-
state structure. We are now able to present four
examples of the type (Au-L)(v-diphos)(Au-X) where L
represents thiophenol and X thiophenol and/or chloride
[29]. The present paper reports on the synthesis, X-ray
molecular structure analysis, and the ligand scrambling
reactions in solutions of thiolatogold(I) complexes to-
gether with X-ray structure analysis on the molecular
structure and the crystal packing of Au(SPh)PPh3, the
crystal structure of which was reported in 1993 by
Schmidbaur et al. and in 1994 by Fackler et al. without
information on crystal packing [30].
6.99 (t, 2H, o-SPh), 7.11 (t, 1H, p-SPh). 31P{1H} NMR
(CDCl3): l 39.2 (s). These NMR data are close to those
reported by Schmidbaur et al [30]. Anal. Calc. for
C24H20AuPS: C, 50.71; H, 3.55. Found: C, 50.47; H,
3.48%.
2.3. Synthesis of
(AuSPh)2{trans-1,2-bis(diphenylphosphino)ethylene} (2)
A similar procedure to that of 1 was employed. To a
THF suspension (20 ml) of (AuCl)2(v-trans-dpen) (215
mg, 0.25 mmol) was added (n-Bu)3SnSPh (196 mg, 0.49
mmol) and the mixture was refluxed for 2.5 h. After
being cooled to room temperature (r.t.), the solvent was
distilled at reduced pressure to leave a pale yellow solid.
This solid was washed with hexane (25 ml) and then
with benzene (70 ml) and the pale yellow residue was
extracted with CH2Cl2 (50 ml). The solvent was vac-
uum-stripped from the extract to leave pale-yellow solid
of 2 (yield 194 mg, 79%). Single crystals for X-ray
analysis were grown from CH2Cl2–hexane. 2 was also
obtained from the reaction of (AuCl)2(v-cis-dpen) with
PhSH and KOH in CH2Cl2–acetone in similar yield.
1H NMR (CDCl3, 270MHz): l 7.46–7.65 (m, 24H,
PPh, m-SPh), 6.94–7.08 (m, 6H, o-SPh, p-SPh), 7.29 (t,
2H, JP–H=18.8 Hz, HCꢀ). 31P{1H} NMR (CDCl3): l
35.87 (s). Anal. Calc. for C38H32Au2P2S2: C, 45.25; H,
3.20. Found: C, 44.73; H, 3.14%.
2. Experimental
2.1. General procedure
All reactions were carried out under a purified nitro-
gen atmosphere using Schlenk and vacuum line tech-
niques. Solvents were dried by standard methods and
distilled under nitrogen. Dppfe (dppfe=1,1%-bis(-
diphenylphosphino)ferrocene) and cis-dpen (dpen=
1,2-bis(diphenylphosphino)ethylene) were purchased
from Strem Chemicals and trans-dpen was purchased
from Aldrich. HAuCl4 was purchased from Tanaka
Precious Metals Co. PhSH and PPh3 were obtained
2.4. Synthesis of
(AuSPh)2{v-1,1%-bis(diphenylphosphino)ferrocene} (3)
A similar procedure to that of 1 was employed. A
611 mg (0.6 mmol) sample of (AuCl)2(v-dppfe) was
dissolved in THF (25 ml) and to this was added 499 mg
(1.25 mmol) of (n-Bu)3Sn(SPh). The yellow solution
was refluxed for 2.5 h. After being cooled to r.t., the
resulting yellow precipitates were collected on a frit and
washed with THF (20 ml) and then with petroleum-
from
Wako
Chemicals.
(AuCl)2(v-cis-dpen),
and
(AuCl)2(v-trans-dpen),
(AuCl)2(v-dppfe)
Au(PPh3)Cl were prepared by literature methods [31–
34]. (n-Bu)3SnSPh was prepared as previously reported
[35].
1
ether (20 ml) to leave 587 mg, (84%) of 3. H NMR
(CDCl3, 300 MHz): l 7.38–7.54 (m, 20H, PPh), 7.09–
7.14 (m, 4H, o-SPh), 7.60–7.65 (m, 4H, m-SPh), 6.99
(t, 2H, p-SPh), 4.18–4.20 (m, 4H, C2-H in Cp), 4.64–
4.65 (m, 4H, C3-H in Cp). 31P{1H} NMR (CDCl3): l
32.80 (s). Anal. Calc. for C46H38Au2FeP2S2: C, 47.36;
H, 3.28%. Found: C, 46.77; H, 3.31%.
2.2. Synthesis of Au(SPh)PPh3 (1)
A 445 mg sample (0.90 mmol) of AuCl(PPh3) was
suspended in THF (60 ml) and to this was added a
slight excess of (n-Bu)3SnSPh (425 mg, 1.07 mmol). The
mixture was refluxed for 20 h. Then the solvent was
distilled off at reduced pressure to leave a pale yellow
oil. The oil was treated with a small amount of hexane
to remove some soluble components and the residue
was extracted with benzene. A white solid was left upon
distillation of the benzene and this was recrystallized
from benzene–hexane (1:1) to afford single crystals of
Au(SPh)PPh3 (1) (yield 475 mg, 93%). 1H NMR
(CDCl3, 300 MHz): l 7.43–7.63 (m, 17H, PPh, m-SPh),
2.5. Synthesis of (AuSPh)(v-trans-1,2-
bis(diphenylphosphino)ethylene}(AuCl) (4)
An 861 mg (1.0 mmol) sample of (AuCl)2(v-trans-
dpen) was dissolved in a mixed solvent of CH2Cl2 (60
ml) and acetone (50 ml). To this was added a MeOH
solution (30 ml) of PhSH (110 mg, 1.0 mmol) and KOH

102
S. Onaka et al. / Inorganica Chimica Acta 312 (2001) 100–110
(28 mg, 0.53 mmol) and the mixture was stirred at r.t.
for several hours. The solvent was distilled off at re-
duced pressure to leave pale yellow solid. This solid was
recrystallized from benzene to afford pale yellow crys-
tals of 4. Yield 360 mg (41%). 4 was also obtained from
the reaction of (AuCl)2(v-cis-dpen) with PhSH and
refinements for carbon atoms made the thermal
parameters negative for more than ten carbon atoms
for these compounds; carbon atoms in all the phenyl
rings of 2 were refined as rigid ring atoms. We repeated
the processes and methods for recrystallization many
times to obtain good quality crystals. The crystals used
for measurements were the best ones so far. The final R
and Rw values are also listed in Table 1. At first we
suspected that a small amount of impurities contained
in the crystals as a result of co-crystallization rather
than imperfection of the crystals should be responsible
for high values of R for 2, 3, and 5 as was suggested
previously by Parkin and Rheingold [37]. As was de-
scribed in the Section 2, elemental analysis on 4 has
given less satisfactory results, but the R value is rather
satisfactory. Instead, R values for 2 and 3 which show
satisfactory elemental analyses are high. It is difficult at
present for us to conclude which factor is responsible
for high R values for these crystals. Tables for atomic
coordinates, thermal parameters, and bond lengths and
angles are available as supporting information. Selected
bond-lengths and angles are shown in Tables 2–6.
1
KOH in CH2Cl2–acetone in a similar yield. H NMR
(CDCl3, 300 MHz): l 7.48–7.63 (m, 22H, PPh, m-SPh),
6.95–7.08 (m, 3H, o-SPh, p-SPh), 7.22 (t, 2H, JP–
Hꢀ19.3 Hz, HCꢀ). 31P{1H} NMR (CDCl3): l 32.64 (s).
Anal. Calc. for C32H27Au2ClP2S: C, 41.11; H, 2.91.
Found: C, 40.04; H, 2.97%.
2.6. Synthesis of
(AuSPh){[v-1,1%-bis(diphenylphosphino)ferrocene}
(AuCl) (5)
To a mixed solvent of CH2Cl2 (30 ml) and acetone
(25 ml), (AuCl)2(v-dppfe) (510 mg, 0.5 mmol) was
dissolved. A methanol solution of PhSH (55 mg, 0.5
mmol) and KOH (30 mg, 0.5 mmol) was added to this
solution and the mixture was stirred for several hours.
The solvents were vacuum-stripped to leave an orange
product. The product was washed with 20 ml of hexane
and extracted with benzene (50 ml). The distillation of
benzene from the extract afforded the orange product
2.8. NMR study on ligand-exchange reactions in a
solution
1
5. Yield 470 mg, 86%. H NMR (CDCl3, 300 MHz): l
Solutions of 3, 5 (5.0 and 20.0 mmol) and (AuCl)2(v-
dppfe) (6) in CDCl3 were subjected to the measurement
of 31P{1H} NMR spectra and similarly prepared 1.0
and 10.0 mmol solutions of 3, 5 and 6 were employed
7.41–7.54 (m, 20H, PPh), 7.12 (t, 2H, o-SPh), 7.62–
7.65 (m, 2H, m-SPh), 6.99 (t, 1H, p-SPh), 4.22–4.25
(m, 4H, C2-H in Cp), 4.68 (s, 4H, C3-H in Cp). 31P{1H}
NMR (CDCl3): l 30.43 (s).
1
for H NMR spectral measurements to assay the con-
centration effect. For 2 and 4, 1.0, 5.0 and 20.0 mmol
solutions in CDCl3 were used for 1H and 31P{1H}
NMR spectral measurements, while only the 3.0 mmol
solution of (AuCl)2(v-trans-dpen) (7) was used because
of low solubility in CDCl3. Deuterated THF was also
used for NMR measurements of 2, 4, and 5 to explore
2.7. X-ray crystallography on 1, 2, 3, 4, and 5
Suitable crystals of these five compounds were ob-
tained by recrystallization from CH2Cl2–hexane. The
selected crystals were glued to the top of a fine glass
rod. Accurate cell dimensions were obtained by least-
square refinements of 22–25 reflections on a MAC
MXC3 diffractometer equipped with graphite-
monochromated Mo Ka radiation. The reflection data
were collected at r.t. for 1, 2, and 3 and at −100°C for
4 and 5 by use of an Oxford cryostream cooler. Com-
plete crystal data are given in Table 1. The structures of
1 and 2 were solved by the direct method, Dirdif, and
that of 3 by SIR92 in a Crystan-GM program package
and those of 4 and 5 by SHELXS86 in a Crystan
program package; these program packages were pro-
vided by MAC Science. An analytical absorption cor-
rection was applied for 4 and 5 [36]. The structures
were refined by full-matrix least-squares with an-
isotropic thermal parameters for all non-hydrogen
atoms except 2, 4, and 5 by an aforementioned Crystan-
GM and a Crystan program package. Refinements were
made anisotropically for heavy atoms and isotropically
for carbon atoms in 2, 4, and 5, because anisotropic
1
the solvent effect on the ligand scrambling. H NMR
spectra were recorded on a Varian Gemini-2000 (300
MHz) and/or JEOL FT/EX-270 (270 MHz) spectrome-
ter and 31P{1H} NMR spectra were recorded at 80.984
MHz on a Varian XL-200 spectrometer equipped with
a temperature controller. 31P{1H} NMR chemical shifts
are referenced to external 85% H3PO4.
3. Results and discussion
3.1. Synthesis
Replacement of two Cl groups in (AuCl)2(v-diphos)
has been achieved by two methods, that is, the reaction
with Sn(SPh)(n-Bu)3 and the reaction with HSPh–
KOH; the use of Sn(SPh)(n-Bu)3 for replacement of the
halogen by the SPh group has precedent in the synthe-
sis of Mn4(SPh)4(CO)12 from Mn2(CO)8Br2 and Sn-

S. Onaka et al. / Inorganica Chimica Acta 312 (2001) 100–110
103
Table 1
Crystal data
Compound
AuSPh(PPh3) (1)
(AuSPh)2
(AuSPh)2(v-dppfe) (AuSPh)(v-trans-dpen) (AuSPh)(v-dppfe)(AuCl)·
(v-trans-dpen) (2) (3)
(AuCl) (4)
CH2Cl2 (5)
Formula
C24H2OAuPS
568.4
triclinic
C38H32Au2P2S2
1008.6
triclinic
C46H38Au2FeP2S2
1166.6
triclinic
C32H27Au2ClP2S
934.9
monoclinic
Aa
15.520(4)
19.010(5)
11.715(4)
C40H33AuClP2S
1177.8
triclinic
Formula weight
Crystal system
Space group
(
(
(
(
P1
P1
P1
P1
,
a (A)
11.552(3)
16.766(4)
11.030(2)
93.51(2)
93.23(2)
97.00(2)
2112.1(8)
4
12.527(3)
15.383(2)
9.740(1))
96.55(1)
91.95(2)
70.50(2)
1757.8(6)
2
10.147(4)
13.032(6)
8.652(3)
106.32(4)
105.62(3)
101.80(4)
1007.8(7)
1
12.391(6)
20.035(7)
8.479(3)
92.58(3)
103.83(3)
76.45(4)
1987(l)
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
108.73(2)
3
,
V (A )
3273(2)
4
1.90
Z
2
1.83
Dcalc (g cm−3
)
1.79
1.91
1.92
Crystal dimensions
0.45×0.25×0.20
0.25×0.20×0.20
0.45×0.20×0.05
0.40×0.20×0.20
0.55×0.25×0.l5
(mm3)
v (Mo Ka) a (cm−1
Scan type
)
41.15
46.30
ꢀ
41.8
2q−ꢀ
1.65+0.35 tan q
5.0
50.0
42.3
ꢀ
2q−ꢀ
1.50+0.35 tan q
6.0
2q−ꢀ
1.70+0.35 tan q
6.0
Scan range
1.55+0.35 tan q
5.0
50.0
2.60+0.35 tan q
6.0
45.0
Scan speed (° min−1
2qmax (°)
)
50.0
50.0
55.0
Temperature (K)
Unique reflections
Reflections with
ꢀFoꢀ\n|(ꢀFoꢀ)
298
5516
4541 (n=4)
298
5519
3941 (n=3)
298
3551
2981 (n=4)
173.2
3758
2518 (n=3)
173.2
5175
3044 (n=4)
No. of parameters
refined
487
403
247
187
246
b
R
0.075
0.113
0.091
0.137
0.126
0.154
0.067
0.10
0.114
0.141
c
Rw
a
,
Mo Ka radiation (u=0.71073 A).
b R=SꢀꢀFoꢀ−ꢀFcꢀꢀ/ꢀFoꢀ.
c Rw=[S(ꢀFoꢀ−ꢀFcꢀ)2/Sw(Fo)2]1/2 where w=1/|2(F).
(SPh)(n-Bu)3 [37,38]. The yields of the product by both
methods are comparable and are relatively high. 1 was
synthesized previously from the reaction of Ph3PAuCl
with PhSH and Et3N by Shmidbaur et al., but the yield
was less satisfactory compared with that of our meth-
ods [30]. Substitution of SPh for one Cl has been made
by the latter method to obtain 4 and 5. This is the first
report on the synthesis of (AuSR)(v-diphos)(AuCl)
type mixed thiolatogold complexes to the best of our
knowledge. However, the yield of mono-substituted 4 is
less satisfactory. The reason has been lately clarified by
NMR study on the facile ligand scrambling reaction of
the monosubstituted product in solution. Results on
elemental analyses for 1–3 are satisfactory, but the
results on 4 are rather unsatisfactory; the finding sug-
gests that small amounts of impurities should be con-
tained in the crystals. Elemental analysis of 5 has not
yet been made. Attempts to substitute SPh for Cl in
(AuCl)2(v-cis-dpen) with PhSH and/or Sn(SPh)(n-Bu)3
have shown that the cis-backbone is isomerized to the
Table 2
,
Selected bond-lengths (A) and angles (°) of 1
Au1ꢁAu2
Au2ꢁP2
P1ꢁC31
P2ꢁC71
Au2ꢁS2
S2ꢁC7
3.145(2)
2.28(1)
1.78(4)
1.71(4)
2.32(1)
1.79(4)
1.89(4)
Au1ꢁS1
S1ꢁC1
P1ꢁC41
Au1ꢁP1
P1ꢁC21
P2ꢁC61
2.30(1)
1.77(4)
1.81(3)
2.263(9)
1.82(3)
1.81(5)
P2ꢁC51
S1ꢁAu1ꢁP1
Au2ꢁAu1ꢁP1
Au1ꢁS1ꢁC1
Au1ꢁP1ꢁC31
Au2ꢁP2ꢁC61
Au2ꢁAu1ꢁS1
Au1ꢁP1ꢁC21
P1ꢁAu1ꢁAu2ꢁP2
(torsional angle)
175.9(4)
103.5(3)
109(1)
116(1)
112(2)
75.9(3)
116(1)
100.3(4)
S2ꢁAu2ꢁP2
Au1ꢁAu2ꢁS2
Au2ꢁS2ꢁC7
Au1ꢁP1ꢁC41 111(1)
Au2ꢁP2ꢁC71 115(1)
Au1ꢁAu2ꢁP2 102.7(3)
Au2ꢁP2ꢁC51 110(3)
179.3(4)
77.8(3)
107(1)

104
S. Onaka et al. / Inorganica Chimica Acta 312 (2001) 100–110
Table 3
3.2. Molecular structure
,
Selected bond-lengths (A) and angles (°) of 2
The final R factors for 2, 3, and 5 are relatively high
because of the poor quality of the crystals used for
measurements. The results, however, are satisfactory
for our purposes to ascertain the existence of au-
rophilicity and to explore supra-structures in solid
states. The reason why it is difficult to obtain good
quality crystals will be discussed later. The molecular
structures presented by ORTEP drawings are shown in
Figs. 1–5. The structure of 1 (Fig. 1) was solved as a
Au1ꢁAu2
Au2ꢁP2
S2ꢁC31
P1ꢁC23
Au2ꢁS2
C2ꢁC2%
P2ꢁC2
3.023(2)
2.18(2)
1.67(1)
1.80(5)
2.24(3)
1.32(9)
1.89(7)
1.7(1)
Au1ꢁS1
C1ꢁC
2.33(2)
1.29(6)
1.83(5)
1.89(7)
2.27(1)
1.78(6)
1.67(5)
1.79(7)
P1ꢁC1
P2ꢁC2
Au1ꢁP1
S1ꢁC11
P1ꢁC17
P2ꢁC43
P2ꢁC37
S1ꢁAu1ꢁP1
Au2ꢁS2ꢁC31
C1ꢁP1ꢁC17
C2ꢁP2ꢁC43
S2ꢁAu2ꢁP2
Au1ꢁP1ꢁC1
S1ꢁAu1ꢁAu2ꢁS2
(torsional angle)
173.4(6)
112(6)
116(2)
101(3)
176.4(6)
111(2)
106.2
Au1ꢁS1ꢁC11 100(2)
Au2ꢁP2ꢁC2
C2ꢁP2ꢁC37
P2ꢁC2ꢁC2%
C1ꢁP1ꢁC23
P1ꢁC1ꢁC1%
113(2)
106(3)
120(5)
102(2)
120(3)
,
dimer; the Au···Au distance is 3.145(2) A, which indi-
cates an aurophilic interaction [20–28]; the geometry of
1 is essentially identical to that reported by Shmidbaur
et al. and Fackler et al. (r(AuꢁAu)=3.1355(3) and
,
3.154(2) A) [30]. The structure of 2 was also solved and
refined as a dimer (Fig. 2); the Au···Au distance is
,
3.023(2) A. This distance also indicates an aurophilic
interaction [20–28]. The structure of 3 was solved and
Table 4
,
Selected bond-lengths (A) and angles (°) of 3
Table 6
Au1ꢁS1
Fe1ꢁC3
P1ꢁC1
Au1ꢁP1
Fe1ꢁC4
P1ꢁC12
2.316(9)
2.07(4)
1.76(3)
2.274(8)
2.05(4)
1.82(3)
Fe1ꢁC1
Fe1ꢁC5
P1ꢁC18
Fe1ꢁC2
S1ꢁC6
2.01(3)
2.04(4)
1.87(3)
2.05(4)
1.77(4)
,
Selected bond-lengths (A) and angles (°) of 5
Au1ꢁP1
Fe1ꢁC1
Fe1ꢁC5
Fe1ꢁC9
P1ꢁC17
P2ꢁC37
Au1ꢁC11
Fe1ꢁC2
Fe1ꢁC6
Fe1ꢁC10
P1ꢁC23
2.25(1)
2.06(5)
2.03(4)
2.05(6)
1.82(4)
1.84(4)
2.29(2)
2.09(5)
2.02(5)
2.11(5)
1.82(5)
Au2ꢁP2
Fe1ꢁC3
Fe1ꢁC7
S1ꢁC11
P2ꢁC6
Au2ꢁS1
Fe1ꢁC4
Fe1ꢁC8
P1ꢁC1
2.26(1)
1.95(5)
2.02(5)
1.59(9)
1.78(5)
2.28(2)
2.01(5)
2.07(5)
1.78(5)
1.84(5)
S1ꢁAu1ꢁP1
Au1ꢁP1ꢁC12
Au1ꢁS1ꢁC6
170.7(3)
106.8(9)
102(2)
Au1ꢁP1ꢁC1
Au1ꢁP1ꢁC18
117(1)
114(1)
P2ꢁC31
Table 5
,
Selected bond-lengths (A) and angles (°) of 4
P1ꢁAu1ꢁC11
P2ꢁAu2ꢁS1
Au2ꢁP2ꢁC6
Au1ꢁP1ꢁC23
Au2ꢁS2ꢁC11
177.0(5)
176.4(5)
115(2)
106(2)
114(2)
Au1ꢁP1ꢁC1
Au1ꢁP1ꢁC17
Au2ꢁP2ꢁC37
Au2ꢁP2ꢁC31
111(2)
117(2)
112(2)
112(2)
Au1ꢁAu2
Au1ꢁC11
P2ꢁC2
P2ꢁC29
Au2ꢁS1
C1ꢁC2
3.093(2)
2.32(2)
1.93(4)
1.86(3)
2.23(1)
1.38(6)
1.84(5)
Au1ꢁP1
S1ꢁC5
P1ꢁC17
Au2ꢁP2
P1ꢁC1
2.27(1)
1.86(7)
1.81(5)
2.21(1)
1.65(4)
1.82(3)
P2ꢁC23
P1ꢁC11
Au1ꢁAu2ꢁS1
Au2ꢁAu1ꢁC11
Au2ꢁP2ꢁC2
Au1ꢁP1ꢁC11
Au2ꢁP2ꢁC29
Au1ꢁAu2ꢁP2
S1ꢁAu2ꢁP2
82.0(6)
79.7(6)
109(1)
105(2)
114(1)
Au2ꢁAu1ꢁP1
Au1ꢁP1ꢁC1
Au2ꢁS1ꢁC5
Au2ꢁP2ꢁC23
P1ꢁAu1ꢁC11
Au1ꢁP1ꢁC17
103.6(5)
118(1)
97(2)
122(1)
174.3(7)
98(2)
102.0(4)
175.2(7)
trans-backbone and (Au-SPh)2(v-trans-dpen) (2) is pro-
duced. Similar attempts to synthesize (AuSPh)(v-cis-
dpen)(AuCl) have yielded the trans isomer 4. Reactions
have been carried out with a simple method of shielding
from light. Rigorous shielding from light seems neces-
sary to yield cis-isomers as was demonstrated by Bruce
et al. for photo-isomerization of (AuX)2(v-cis-dpen) to
(AuX)2(v-trans-dpen) [39].
Fig. 1. The ORTEP drawing of Au(PPh3)(SPh) (1) which shows the
dimer structure.

S. Onaka et al. / Inorganica Chimica Acta 312 (2001) 100–110
105
AuꢁCl group are in a trans position. Therefore, intra-
molecular aurophilic interaction is impossible. The
molecular structure of 5 was also solved and refined for
a single molecule. 5 crystallizes with one CH2Cl2
molecule. However, two Cl atoms in CH2Cl2 are disor-
dered in three positions and thus refined with 2/3
weight for each Cl atom. The Au-SPh group and the
AuꢁCl group in 5 are in a staggered conformation.
Intramolecular aurophilic interaction is again impossi-
ble. In the dimer 1, the phenyl group (C7–C12) of the
SPh coordinated to Au2 is almost parallel and in close
proximity to one of the phenyl groups (C31–C36) of
PPh3 which is coordinated to Au 1. The finding sug-
gests the formation of an ‘intramolecular’ p–p interac-
tion if we treat the dimer of 1 as a molecule. This type
of ‘intramolecular’ p–p interaction is not formed in 2
for a single dimer unit and in 3–5 for a single molecule.
Fig. 2. The ORTEP drawing of (AuSPh)2(m-trans-dpen) (2) which
shows the dimer structure.
,
AuꢁP distances in 1 are 2.263(9) and 2.28(1) A, which
are longer than that of similar phosphine gold-thiolate,
,
Au(PPh3)(8-qnS) (2.248(7) A) [40]. AuꢁP distances in 2
,
are 2.27(1) and 2.18(2) A, which are close to that of
,
(AuCl)2(v-trans-dpen) (2.235(2) A) [32] and that of
[Au2(p-thiocresol)2(1,5-bis(diphenylphosphino)pentane]
,
,
(2.260(1) A) [26]. The AuꢁP distance in 3 is 2.274(8) A.
,
The AuꢁP distances in 4 are 2.21(1) A (trans to SPh)
,
and 2.27(1) A (trans to Cl). These distances in 5 are
2.26(1) (trans to SPh) and 2.25(1) A (trans to Cl). AuꢁS
distances are 2.30(1) and 2.32(1) in 1, 2.24(3) and
,
,
2.33(2) in 2, 2.316(9) in 3, 2.23(1) in 4, and 2.28(2) A in
5, respectively. These distances are close to that of
Au(PPh3)(8-qnS) (2.296(8)) [40], those of [Au2-
(p - thiocresol)2(1,4 - bis(diphenylphosphino)butane]
(2.301(2)) and of Au2(p-thiocresol)2(1,5-bis-(diphenyl-
Fig. 3. The ORTEP drawing of (AuSPh)2(m-dppfe) (3).
,
phosphino)pentane] (2.313(3) A) [26]. The AuꢁS dis-
tances in quite analogous [8] (1,1%)ferrocenophane,
,
[Au2S2(CH2)3](dppfe), are 2.289(4) and 2.295(4) A [41].
3.3. Crystal structure
The drawings of the crystal packing for 1 (Fig. 6), 2
(Fig. 7), and 4 (Fig. 8) exhibit interesting features. The
projection of the molecular packing of 1 along the b
Fig. 4. The ORTEP drawing of (AuSPh)(m-trans-dpen)(AuCl) (4).
refined for a single molecule (Fig. 3). Two Au-SPh
groups are in a staggered conformation (180°) and thus
an intramolecular aurophilic interaction is impossible.
The molecular structure of 4 was solved and refined for
a single molecule (Fig. 4). The Au-SPh group and the
Fig. 5. The ORTEP drawing of (AuSPh)(m-dppfe)(AuCl) (5).

106
S. Onaka et al. / Inorganica Chimica Acta 312 (2001) 100–110
Bulky R groups in these compounds are a deterrent for
p–p interactions among aromatic rings as in 1 and such
a p–p interaction seems to be germane to the au-
rophilicity for Ph3PAu(SꢁAr) (Ar=an aromatic ring)
type compounds. A projection of the molecular packing
along the c axis is displayed in Fig. 7, which demon-
strates the formation of an infinite chain polymer con-
necting (AuSPh)2(v-trans-dpen) units by Au···Au
interaction. The gross polymer structure composed
from AuꢁPꢁCꢀCꢁPꢁAu units is parallel along the b
axis. In addition, the neighboring chains are connected
with partial p–p stacking between the phenyl rings of
the SPh groups (S2C31ꢁC36, hatched) which are coor-
dinated to Au2; the closest contact between carbon
,
atoms in these phenyl rings is 3.0(1) A. In this way,
two-dimensional layered structure is composed by au-
rophilicity and p–p interaction. This layered structure
of 2 is reflected in its mechanical property; a single
crystal of 2 is easily cleaved by applying a slight pres-
sure along the ab plane. This type of network structure
has not yet been reported for (AuCl)2(v-trans-dpen) (7)
[32] and (AuCl)2(v-cis-dpen) [42]. The projection of the
molecular packing along the b axis for (AuSPh)(v-
trans-dpen)(AuCl) (4) (Fig. 8) demonstrates the forma-
tion of an infinite chain polymer connecting
(AuSPh)(v-trans-dpen)(AuCl) units by Au···Au interac-
Fig. 6. The projection of the crystal structure of Au(PPh3)(SPh) (1)
along the b axis, which shows a tetramer structure.
,
tion (r(Au···Au)=3.093(2) A). The gross core structure
composed from the AuꢁPꢁCꢀCꢁPꢁAu unit is parallel
along the a axis and thus SPh groups and C1 groups
are parallel, respectively, to each other along the a axis.
The Au···Au distance in 4 is slightly longer than that of
,
2 (r(Au···Au)=3.023(2) A). This finding supports our
expectation that the effect of the SPh group on the
aurophilicity is stronger than that of Cl as mentioned
Fig. 7. The projection of the crystal packing of (AuSPh)2(m-trans-
dpen) (2) along the c axis, which shows the two-dimensional network.
axis (Fig. 6) shows a dimer of dimer structure which is
composed by two kind of weak interactions, aurophilic-
ity and p–p interaction between a phenyl group of
PPh3 (Ph61) coordinated to Au2 and the phenyl group
of SPh (Ph71) coordinated to Au2. The Ph71 phenyl
group of the SPh ligand overlaps with the Ph61 phenyl
,
ring and the closest interatomic distance is 3.22(4) A
among twelve carbon atoms. These distances are good
evidence to indicate a p–p interaction between these
two phenyl groups. This type of oligomer structure has
not yet been reported for 1 to the best of our knowl-
edge [30]; Schmidbaur et al. reported also molecular
structures of relevant Ph3PAu(S-2, 4, 6-R3C6H2) (R=
Et and/or iPr) compounds. Au···Au interaction, how-
ever, was not demonstrated for these compounds [30].
Fig. 8. The projection of the crystal packing of (AuSPh)(m-trans-
dpen)(AuCl) (4) along the b axis, which shows the one-dimensional
infinite structure.

S. Onaka et al. / Inorganica Chimica Acta 312 (2001) 100–110
107
above. Similar projections of the molecular packing
along the a, b or c axes have been made for dppfe
derivatives, 3 and 5. However, the closest Au···Au
begets one peak for 4 and 5. Appraisal of the reso-
nances for these complexes has shown that the chemical
shift of 4 is close to the center of the signals of 2 and 7
and that of 5 to the center of resonances of 3 and 6. We
have made NMR measurements for a mixed solution of
2 and 7, and of 3 and 6 with the ratio 1:1, respectively,
,
contact is 5.768(3) for 3 and 5.862(3) A for 5, respec-
tively, which are beyond the regime of the aurophilicity.
In addition, there is no close contact between phenyl
groups which suggests a p–p interaction. Therefore,
construction of an infinite structure and/or a multidi-
mensional array is impossible under these conditions.
Our initial strategy to construct a multidimensional
array and/or an infinite chain structure by use of aug-
mented aurophilicity in substituted Au(I) complexes
with SR group(s) has now been demonstrated in 2 and
4 with and without collaboration of weak p–p interac-
tion for less bulky diphosphines such as trans-dpen; this
kind of infinite structure has been demonstrated previ-
ously for (AuX)2(v-diphos) where X stands for Cl
and/or I and diphos is Ph2P(CH2)nPPh2 (n=4, 5, 6, 7,
and 8) by Balch et al. [43]. Next we are interested in the
role of phosphines for making such a suprastructure.
From the inspection of the results on the crystal pack-
ing for these five thiophenol gold complexes 1–5, it
may be envisaged that the bulky diphosphine ligand
such as dppfe is detrimental to the formation of a
supramolecular array in the solid state. However, we do
not allege that bulky diphosphines cannot induce the
aurophilicity itself, because Lacruna et al. have success-
fully synthesized several Au-dppfe complexes such as
[S(Au2dppfe)] which have intramolecular Au···Au inter-
actions with the aid of the element, S and/or a ligand
containing S to force gold atoms to come close [44]. In
addition we [45] and Rheingold et al. have successfully
synthesized mixed gold-transition metal clusters such as
(Au2dppfe)Re2(CO)9 and [(Au2dppfe)(AuCl)BRhRu3-
1
in CDCl3. H NMR measurements for the former com-
bination have shown a pseudo triplet at l 7.22 for
ethylene protons which coincides with the pseudo
triplet of 4 (l 7.22) at room temperature and is in
agreement with the center of pseudo triplets of 2 (l
7.29) and 7 (l 7.15). 31P{1H} NMR measurement of the
latter combination has shown a singlet at l 30.98,
which is quite close to that of 5 (30.43). The mixed
solution of 2 and 7 with a 2:1 ratio in CDCl3 at room
temperature yields a triplet at l 7.245 which is in good
agreement with the calculated value, (7.29×2+7.15×
1)/3=7.243. These experiments support the idea that
complexes 4 and 5 are in equilibrium for ligand ex-
change and/or scrambling:
2ClAuPSPAuSPh ? ClAuPSPAuCl
+PhSAuPSPAuSPh
where PSP is the trans-dpen and/or dppfe. In order to
get more information on this process two additional
experiments have been made, that is, the concentration
and the temperature effect on the exchange process.
However, no concentration effect has been detected by
HCp*(CO)9] in which dppfe bridges
a covalent
goldꢁgold bond [46]. These examples suggest that a
weaker aurophilic interaction than the covalent
goldꢁgold bond, i.e. intermolecular aurophilicity,
should be easily induced between molecules with the aid
of a collaboration of weak interactions such as hydro-
gen bonding. This line of study to construct
supramolecular arrays by use of dppfe derivatives of
Au(I) is under investigation in our laboratory.
3.4. NMR study on the ligand exchange reactions in
solutions
The trans-dpen complexes 2, 4, and 7 and the dppfe
complexes 3, 5, and 6 each exhibit one phosphorus
resonance at l 35.87, 32.64, 29.48, 32.80, 30.43, and
27.80, respectively, for 31P{1H} NMR spectra in CDCl3
at 25°C; the peaks of 4 and 5 are slightly broader than
the others. The X-ray molecular structure analysis of 4
and 5 indicates that two phosphorus atoms should be in
a different magnetic environment. Thus NMR results
suggest that some kind of exchange process in solutions
Fig. 9. The upfield shift of the 31P NMR chemical shift of 5 with
lowering the temperature.

108
S. Onaka et al. / Inorganica Chimica Acta 312 (2001) 100–110
Fig. 10. Temperature-dependent 1H NMR spectra of the cyclopentadienyl protons for 5 in d8-THF.
31P{1H} NMR spectroscopy for 4 (1.0 and 20.0 mmol
solutions) and for 5 (1.0 and 10.0 mmol solutions) in
CDCl3 at room temperature. In the temperature depen-
dent 31P NMR measurements, the signals of 4 and 5 are
broadened with lowering the temperature from +50 to
−50°C in CDCl3. However, the peak never splits into
a doublet and/or multiplet and no definitive coalescence
has been detected within this range of temperature.
Although these broadenings support the idea that 4 and
5 are amenable to the ligand scrambling, one plausible
question is why the exchange is so rapid even at −
50°C. Previous studies by Balch’s group [47] and by
Lin’s group [48] may provide some clue to this ques-
tion; both groups have demonstrated by 31P NMR and
UV–Vis spectroscopy that some dinuclear Au(I) com-
plexes bridged by diphosphine ligands are associated to
some extent through the intermolecular Au···Au inter-
action (aurophilicity) even in solution. Under our ex-
perimental conditions, the change in concentrations for
1H NMR and 31P NMR measurements is more than ten
times. However, the results from both measurements
are consistent and no concentration dependence is ob-
served. We then have suspected that the ligand scram-
bling proceeds via the exchange of the Cl atom in 4 or
5 with the Cl atom of CDCl3 or Cl− contained as an
impurity in the NMR solvent. Therefore, we have done
1
similar temperature dependent H NMR measurements
in a nonchlorinated solvent, that is, deuterated THF,
d8-THF with the temperature range from 50°C to
−100°C for 5 to explore the solvent effect on the
1
ligand exchange. The H NMR signals due to Cp ring
protons are observed at l 4.92 and 4.50, respectively,
for 2,5-H and 3,4-H protons as sharper multiplets
compared to those in CDCl3 solution at 25°C. The
signals are broadened with decreasing the temperature,
but do not split even at −100°C. Thus it is unlikely

S. Onaka et al. / Inorganica Chimica Acta 312 (2001) 100–110
109
that chlorine exchange with that of the solvent or Cl−
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Acknowledgements
This research was funded by the Iketani Science and
Technology Foundation and Grants-in-Aid for Scientific
Research on Priority Areas (No. 10149221 ‘Metal-assem-
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