The effect of carbon chain length of the diphosphine ligand on the aurophilic interaction. Synthesis and X-ray structural study for a series of Au(I) compounds with Ph2P-R-PPh2 and S-(CH 2)n-py ligands

Article abstract of DOI:10.1016/j.jorganchem.2004.08.028

The effect of the carbon chain-length for Ph₂P-R-PPh₂ (R = -CHCH-, -CH₂-CH₂-, -CH₂-CH ₂-CH₂-, and -CH₂-CH₂-CH₂- CH₂-) and S-(CH₂)_n-pyridine ligand (n = 0 to 2) on the aurophilic interaction has been explored systematically. The effect of the N position in x-mercaptopyridine (x = 2 or 4) toward Au(I) center and/or the SR group was also investigated. X-ray structural study was made for 12 new derivatives. The Au-Au distances are below 3.0 ? for 2-S-pyridine derivatives with Ph₂P-CHCH-PPh₂ (t-dpen) and Ph ₂P-CH₂-CH₂-PPh₂ (dppe) ligand and the pyridine N atoms come in close contact with the H atoms of these diphosphine carbon chains. A local coplanar conformation is formed between 2-S-pyridine and Au-P-CH groups for these derivatives. The carbon chain lengths are not too consequential on the induction of aurophilicity. Various infinite and/or dimer structures have been revealed from single crystal X-ray analysis for the present series of compounds.

Full text of DOI:10.1016/j.jorganchem.2004.08.028

Journal of Organometallic Chemistry 690 (2005) 57–68
www.elsevier.com/locate/jorganchem
The effect of carbon chain length of the diphosphine ligand on the
aurophilic interaction. Synthesis and X-ray structural study for
a series of Au(I) compounds with Ph2P–R–PPh2 and
S-(CH2)n-py ligands
a,
a
a
b
Satoru Onaka *, Masanobu Yaguchi , Ryuichiro Yamauchi , Tomoji Ozeki ,
a
a
a
Mitsuhiro Ito , Tetsuya Sunahara , Yukako Sugiura , Michito Shiotsuka ,
c
a
Keiko Nunokawa , Makoto Horibe , Kazuya Okazaki , Akifumi Iida ,
a
a
b
b
Hirokazu Chiba , Katsuya Inoue , Hiroyuki Imai , Katsuya Sako
d
d
c
a
Department of Environmental Technology, Graduate School of Engineering, Nagoya Institute of Technology,
Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
Department of Chemistry and Materials Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
b
c
Department of Systems Management and Engineering, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
d
Institute for Molecular Science, Myodaiji, Okazaki 444-8484, Japan
Received 8 June 2004; accepted 18 August 2004
Available online 25 September 2004
Abstract
The effect of the carbon chain-length for Ph2P–R–PPh2 (R = –CH@CH–, –CH2–CH2–, –CH2–CH2–CH2–, and –CH2–CH2–
CH2– CH2–) and S-(CH2)n-pyridine ligand (n = 0 to 2) on the aurophilic interaction has been explored systematically. The effect
of the N position in x-mercaptopyridine (x = 2 or 4) toward Au(I) center and/or the SR group was also investigated. X-ray struc-
˚
tural study was made for 12 new derivatives. The Au–Au distances are below 3.0 A for 2-S-pyridine derivatives with Ph2P–
CH@CH–PPh2 (t-dpen) and Ph2P–CH2–CH2–PPh2 (dppe) ligand and the pyridine N atoms come in close contact with the H atoms
of these diphosphine carbon chains. A local coplanar conformation is formed between 2-S-pyridine and Au–P–CH groups for these
derivatives. The carbon chain lengths are not too consequential on the induction of aurophilicity. Various infinite and/or dimer
structures have been revealed from single crystal X-ray analysis for the present series of compounds.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Aurophilicity; Pyridinethiol; Diphosphine; N–H interaction; Infinite chains
1. Introduction
factors which are important to the appearance and the
strength of the aurophilic interaction. For instance, the
steric effect of ligands and/or the crystal packing force
are sometimes more accentuated than the electronic ef-
fect of ligands or vice versa [4–10]. Pykko¨ et al. [11] have
highlighted the importance of the steric effect of the SR
group from their theoretical calculations. Substitution
of a SR (R = organic group) group for X in XAuPR30
compounds is a well-known stratagem to induce and/
The use of aurophilic interaction is a sophisticated
strategy to construct supra molecules and nanometer-
sized molecules on a gold(I) derivative as a scaffolding
[1–3]. However, there have been many debates on the
*
Corresponding author. Tel.: +81527355160; fax: +8152735516.
E-mail address: onaka.satoru@nitech.ac.jp (S. Onaka).
0022-328X/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.08.028

58
S. Onaka et al. / Journal of Organometallic Chemistry 690 (2005) 57–68
or reinforce the aurophilicity of this type of Au(I) deriv-
atives [11]. Balch et al. [12] have made a systematic study
for a series of (Au–X)2(l2-PPh2–(CH2)n–PPh2) (n = 4 to
8) derivatives and pointed out that Au–Au distances do
not depend simply on the length of the carbon chains,
but the woven structure by the carbon backbone is lar-
gely influential. We have shown that the advent of auro-
philicity depends on the intricate balance among crystal
packing force, steric demands of the phosphine ligand,
each of solid-state molecular structures appears to exist
in solutions at room temperature.
2.2. Molecular structures
The molecular structures of 1–5 which are composed
of P–C@C–P and P–C–C–P skeletons are quite similar
except the tilt of the SR ring (Figs. 1(a)–5(a)). The
crystals 1, 2 and 3 belong to the monoclinic system
2/m (C2/c, P21/n and C2/c, respectively), while 4 and 5
~
and the interaction (p-p stack) between aromatic rings
ꢀ
for a series of (m-CF3–C6H4)3P–Au–X derivatives
(X = Cl, SR) in the previous paper [13]. The previous
paper has also shown that the aurophilicity is weakend
for 4-S-pyridyl derivatives than for the S-phenyl deriva-
tives [13]. This finding has led us to assess the influence
of the S position in the pyridine-thiolate ligand on the
aurophilicity for [Au(x-S-pyridine)]2(l-diphos) type
derivatives (x = 2 and/or 4). The first onset of this study
was made for [Au(2-S-pyridine)]2(l2-t-dpen) (1)
(t-dpen = trans-1,2-bis (diphenyl phosphino) ethylene).
Single crystal X-ray analysis on 1 has revealed two inter-
esting results; a short Au–Au distance and significant
pyridine-Nꢀ ꢀ ꢀH–C (ethylene) contact, indicative of a
hydrogen bond. These serendipitous findings have
enticed us to systematic exploration on [Au(x-S-
pyridine)]2(l2-t-dpen). The present study was under-
taken to glean essential ingredients by changing the
length of carbon chain in the diphosphine and/or pyri-
dine-thiolate ligands and the S-position, by which the
rational design and the fabrication of extended gold-
based molecular assemblies will be possible.
belong to the triclinic system, P. The predominant
molecular shape for 1–5 has a sinusoidal S–Au–P–P–
Au–S skeleton in which the SR groups are oriented to
an opposite direction for each other. There are two inde-
pendent molecules in a unit cell of 5; only one molecule
is shown in Fig. 5(a). The center of symmetry is located
at the midst of the C@C backbone for 1. Similarly, there
is a center of symmetry at the midst of the C–C back-
bone for 3, 4 and each molecule of 5. For the diphos-
phine with a P–C–C–C–P backbone, single crystals
were obtained for the 2-S-pyridine and SPh derivatives
6 and 7. X-ray structure analysis shows a sinusoid chain
structure (Figs. 6(a) and 7(a)). The C–C–C-chains of 6
and 7 exhibit an elongated C–C–C form and the bent
direction of the two Au-2-S-py groups is opposite in 6.
Three kind of substitution products 8–10 were synthe-
2. Results
2.1. Synthesis
The new diphosphine-bridged gold arylthiol com-
plexes (AuSR)2(l-Ph2P–Cn–PPh2) (n = 2 to 4), 1–10,
were synthesized by the reaction of (AuCl)2(l-Ph2P–
Cn–PPh2) with two equivalent amounts of HSR together
with KOH or Na2CO3 in CH2Cl2/CH3OH. Au{4-S-
(CH2)n-pyridines}PPh3, 11 and 12, were similarly syn-
thesized from Au(Cl)PPh3 with 4-HS-(CH2)n-pyridine
(1:1 ratio) together with KOH in CH2Cl2/CH3OH. All
these compounds were obtained in a satisfactory yield.
The 1H NMR spectrum of each compound supports
the synthesis of new respective gold-thiol derivatives,
which was confirmed by single crystal X-ray analysis.
The 31P NMR spectra in CDCl3 exhibit a singlet (ca.
36 ppm) at room temperature for the present series of
SR complexes. Substitution of the SR group for Cl in
the precursor diphosphine Au chlorides induces a con-
siderable lower-filed shift compared with a singlet at
ca. 30 ppm for each parental chloride. The trend is con-
sistent with our previous observations [13–15]. Thus,
Fig. 1. (a) An ORTEP drawing of (2-S-pyridine-Au)2(l2-t-dpen) (1).
(b) Infinites chains composed of aurophilicity for 1. The chains are
almost in the ac plane.

S. Onaka et al. / Journal of Organometallic Chemistry 690 (2005) 57–68
59
Fig. 2. (a) An ORTEP drawing of (4-S-pyridine-Au)2(l2-t-dpen) (2).
(b) The molecular packing of 2 along the c-axis, which shows dimer
formation through aurophilicity interaction. Phenyl groups are omit-
ted for clarity.
sized for the P–C–C–C–C–P diphosphine ligand. All
three these compounds were obtained in a form of single
crystals (Figs. 8(a)–10(a)). The C–C–C–C-chain of 8,
which possesses the 2-S-py ligand as an SR group exhib-
its an elongated C–C–C–C form and the bent direction
of the two Au-2-S-py groups is opposite in 8. The molec-
ular structure of 9 which possesses the 4-S-py ligand is
composed of a rectangular C–C–C–C backbone. Two
independent molecules with distinctly different confor-
mations relevant to the –C–C–C–C– backbone are con-
tained in a unit cell of 10 in which the SPh substitutes for
Spy ligands in 8 and 9. The methylene groups in the
hydrocarbon chain and the phosphorus atoms have anti,
staggered conformations similar to that depicted in Fig.
10(a) for one molecule of 10; in another molecule, the
CH2 groups and the phosphorus atoms have rectangu-
lar, staggered conformations similar to that illustrated
in Fig. 9(a) and the two inside CH2 groups occupy dis-
ordered positions pointed to an opposite direction.
Although 8–10 possess the four hydrocarbon chain in
the diphosphine ligand, the vectors of the two S–Au–P
groups for these molecules are significantly different;
the vectors are almost reversed for 8 and 10, while the
angle between these vectors is loosened significantly
from 180ꢁ for the 4-S-pyridine derivative 9.
Fig. 3. (a) An ORTEP drawing of (2-S-pyridine-Au)2(l2-dppe) (3). (b)
Infinites chains composed of aurophilicity for 3. Phenyl groups are
omitted for clarity.
Fig. 4. An ORTEP drawing of (4-S-pyridine-Au)2(l2-dppe) (4).

60
S. Onaka et al. / Journal of Organometallic Chemistry 690 (2005) 57–68
Fig. 6. (a) An ORTEP drawing of (2-S-pyridine-Au)2(l2-dppp) (6). (b)
Infinite chains composed of aurophilicity and the dppp ligand for 6,
which is almost parallel to the a-axis.
Fig. 5. (a) An ORTEP drawing of (S-Ph-Au)2(l2-dppe) (5). (b) Infinite
chains composed of aurophilicity and the dppe ligand for 5, viewed
down along the a-axis.
In order to assess the effect of the carbon chain length
in S-(CH2)n-py ligand on the conformation of mole-
cules, Au(4-S-CH2-py)PPh3 (11), and Au{4-S-(CH2)2-
py}PPh3 (12) were synthesized and subjected to single
crystal X-ray diffraction analysis. The structures of these
molecules are shown in Figs. 11 (11) and 12 (12). Com-
pounds 11 and 12 exist as an isolated molecule in solid
states. An interesting structural feature of 12 is that
the S–C–C–C(py) backbone is bent back to the Ph3P–
Au moiety.
Selected bond lengths and angles are collected in Ta-
ble 2. As three different kinds of diffractometers were
used to collect the diffraction data and the quality of
data are not at the same level, it seems better to avoid
precise metrical comparisons among these parameters
Fig. 7. (a) An ORTEP drawing of (S-phenyl-Au)2(l2-dppp) (7). (b)
Infinite chains composed of aurophilicity and the dppp ligand for 7,
viewed down along the b-axis.

S. Onaka et al. / Journal of Organometallic Chemistry 690 (2005) 57–68
61
Fig. 8. An ORTEP drawing of (2-S-pyridine-Au)2(l2-dppb) (8).
Fig. 10. (a) An ORTEP drawing of (S-phenyl-Au)2(l2-dppb) (10). (b)
Infinite chains composed of aurophilicity and the dppb ligand for 10,
viewed down along the c-axis.
Fig. 9. An ORTEP drawing of (4-S-pyridine-Au)2(l2-dppb) (9).
except discussions on trends for these derivatives. For
RS–Au–P“P–Au–SR series, Au–S and Au–P distances
˚
fall within normal ranges (ca. 2.31 and 2.26 A, respec-
tively) [13–15]. There is no apparent changes of these
lengths along with the elongation of the carbon back-
bone. The P–Au–S bond angles are almost linear and
there appears no systematic changes with the change
of the carbon backbone; those angles for 7 are the most
acute (167.63(6)ꢁ and 171.26(6)ꢁ). The Au–S–C(ipso) an-
gles are around 109ꢁ. There is also no systematic
changes of these angles with the changes of the carbon
chain.
Fig. 11. An ORTEP drawing of Au (4-S-CH2-pyridine)(PPh3) (11).
scribed above (X = 2-S-py, 4-S-py and S-Ph). Typical
solid-state structural motifs for (AuX)2diphos so far
known are classified into four types A, B, C, and D
and are summarized in Chart 1; there is no Au–Au inter-
action in D. The motifs of 1–10 are A, B, A, D, A, A, A,
D, (A) and A, respectively. Among the crystal packing
diagrams for aforementioned molecules, only archetypal
cases for aurophilic interaction are shown in Fig. 1(b)–
3(b) and 5(b)–7(b) for 1–3, and 5–7. Compounds 1
3. Discussions
3.1. Crystal structures and aurophilicity
Systematic exploration of the substitution effect of X
group and/or diphosphine on the aurophilic interaction
has been made for (AuX)2(diphos)-type compounds de-
and
3
indicate
a
strong Au–Au interaction

62
S. Onaka et al. / Journal of Organometallic Chemistry 690 (2005) 57–68
substitution of the SR group for Cl generally reinforces
aurophilicity [8,16]. However, it is surprising to us that
the 2-S-pyridyl group constricts the Au–Au separation
strongly than the S-phenyl group and/or 4-S-pyridine.
It is unlikely that the subtle difference of the electron
donating ability between 2-S-pyridyl group and the 4-
S-pyridyl group should induce such a dramatic change
of the aurophilicity. Thus the following questions come
out immediately, why 2-S-pyridine derivatives 1 and 3
exhibit such a strong aurophilic interaction, why not
4-S-pyridine derivative 4? What is the most important
factor to influence on the aurophilicity? Details on this
query are described below and it seems appropriate to
continue investigations into the effect of the carbon
chain lengths on the aurophilicity at this moment. Sys-
tematic synthesis and X-ray structure analysis for
diphosphines with C–C–C and C–C–C–C backbones
have been attempted in order to assess the special role
of 2-S-pyridyl group(s) on aurophilicity further. The
crystal structures of 6 (the 2-S-py derivative with the
C–C–C backbone) (Fig. 6(b)) and 7 (the S-Ph derivative
with the C–C–C backbone) (Fig. 7(b)) show quasi one-
dimensional chains which are constructed by connecting
neighboring molecules through Auꢀ ꢀ ꢀAu interactions
Fig. 12. An ORTEP drawing of Au (4-S-CH2-CH2-pyridine)(PPh3)
(12).
˚
(r(Au–Au) = 2.986(1) and 2.9679(2) A for 1 and 3,
respectively) and a quasi one-dimensional infinite chain
is thus formed (Figs. 1(b) and 3(b)). By substituting 4-S-
pyridyl groups for 2-S-pyridyl groups in 1, the N-posi-
tion isomer 2 is obtained. The Au–Au distance in 2 is
˚
significantly elongated (r(Au–Au) = 3.239(2) A) and di-
mers are formed via two Au(I) centers in one molecule
which is connected to an adjacent molecule of 2 (Fig.
2(b)). Compound 4 is formed upon substitution of 4-
S-pyridyl groups for 2-S-pyridyl groups in 3. The Au–
Au interaction is amazingly elongated from r(Au–
˚
˚
(r(Au–Au) = 3.1081(5) A for 6 and 3.1389(5) A for 7).
A similar quasi one-dimensional chain was reported pre-
viously for the starting chloride, but the Au–Au distance
˚
˚
Au) = 2.9679(2) to 5.8749(7) A by this substitution; this
is significantly longer (r(Au–Au) = 3.316 A) [17]. For the
distance is far beyond the Au–Au interaction. By substi-
tuting phenyl groups for 2-S-pyridyl groups in 1 and 3,
(AuSPh)2(l2-t-dpen) [14] and the S-Ph analogue 5 (dppe
backbone) are obtained. For both of them, quasi one-di-
mensional infinite chains are formed; the chain of 5 is
constructed by connecting adjacent independent mole-
cules via two Au(I) centers. The Au–Au distance for
diphosphine ligand with the C–C–C backbone, the spe-
cial role of the 2-S-pyridine on the aurophilicity is dem-
onstrated again in 6. However, the contribution of the 2-
S-pyridine on the aurophilicity is not manifested in 8
where the carbon chain of the diphosphine ligand is
C–C–C–C–. By substituting 4-S-pyridine for 2-S-pyri-
dine, an analogous diphosphine derivative 9 is obtained;
two neighboring molecules are aligned with a head to
tail fashion to form parallelograms with an Auꢀ ꢀ ꢀAu
˚
(AuSPh)2(l2-t-dpen) is 3.023(2) A [14], which is just be-
˚
tween that of the 2-S-pyridine derivative (1) (2.986(1) A)
˚
and the 4-S-pyridine derivative (2) (3.239(2) A). The
˚
contact of 3.626(1) A in 9. Although the observed Au–
˚
Au–Au distance in 5 is 3.0840(6) A, which is between
Au contact is slightly longer than the generally accepted
distances for this interaction [6,11], the aggregation
seems to be the result of this contact to some extent.
Quite interestingly, the S-Ph analogue 10 with the same
alkyl chain diphosphine ligand exhibits the aurophilicity
˚
˚
2.979(2) A (3) and 5.8749(7) A (4). The observation of
an elongated Au–Au distance for 2 and 4 compared with
the S-phenyl analogue (AuSPh)2(l2-t-dpen) and 5 is
consistent with our previous conclusion that the auro-
philicity is weak for the 4-S-pyridyl derivatives com-
pared with the S-phenyl derivatives, although
˚
(r(Au–Au) = 3.0926(5) A). Two independent molecules
of 10 are connected through Au–Au interactions to yield
Chart 1. Structural motifs for diphosphine digold complexes.

S. Onaka et al. / Journal of Organometallic Chemistry 690 (2005) 57–68
63
a chain structure (Fig. 2(g)). The chains are parallel for
each other in solid states. According to Balch et al. [12],
no Au–Au interaction is observed for the parental chlo-
ride. Therefore, the effect of substituting SPh for Cl on
the aurophilicity is evident for 10. The comparison of
the Au–Au distances in the present series of (Au-
SR)2(l-diphosphine) derivatives and in those reported
previously [13,14] indicates following two important
trends. For the S-Ph series, the aurophilicity is less sus-
ceptible to the alkyl chain length in the diphosphine lig-
ands up to C4. However, the aurophilicity is quite
sensitive to the alkyl chain length in the diphosphine lig-
ands for the 2-S-pyridine series. From these trends, we
were hit by an idea what happens on the aurophilicity
by inserting a CH2 group between the S and the pyridine
ring. This idea was first examine by use of the simple tri-
phenylphosphine derivatives. For 11 and 12, no Au–Au
interaction is induced by substituting 4-S-(CH2)n-py for
Cl in the parental Ph3P–Au–Cl [13,15]. Then we have
examined the idea for [Au(4-S-CH2-pyridine)]2(l-t-
dpen). Our preliminary experiment shows a quite inter-
esting result, that is, the insertion of a CH2 group into
the pyridine–S bond makes the Au–Au distance closer
All of the available data mentioned above highlight
the special role of the 2-S-pyridine ligand on the auro-
philcity when the ligand is incorporated into the diphos-
phine ligands with short hydrocarbon backbone. One
plausible explanation of the result is extended in the fol-
lowing section.
3.2. Nꢀ ꢀ ꢀH–C@ interaction and NMR spectra
In the above section, the special role of the 2-S-pyri-
dine group on the aurophilicity was demonstrated in
terms of the outlook of the molecular structure. In this
section, the issue is discussed in terms of detailed
1
X-ray and H NMR data. Calculated crystal densities
(Table 1) do not suggest that the crystal packing force
is directly related to the strength of the aurophilicity.
The ORTEP drawings of 1, 3 and 4 (Fig. 1(a), 3(a)
and 4(a)) have shown an interesting common feature
at first glance; a quasi-coplanar structure is built up
around the central part of each molecule including car-
bon and nitrogen atoms of the pyridine ring. The devia-
tion of the H atom of the core CH–CH diphosphine
from the best plane defined by the RS–Au–P–CH group
˚
˚
from 3.239(2) A (2) to 3.102(3) A [18]; this distance is
shorter than that of (AuCl)2dppe (r(Au–Au) = 3.189(1)
˚
˚
is 0.80 A for 1, and 0.41 A for 3, respectively (calcula-
tions were made after the hydrogen positions were trans-
ferred by the symmetry operation). However, the
deviation from the planarity is larger for 4. In order to
assess this coplanarity in another way, the dihedral
angle between two planes (one is defined from the H–
C1–P1–Au1–S1 array and the other is from the S–pyri-
dine array) is calculated; the angle is 19.1(5)ꢁ for 1, 21.9
(1)ꢁ for 3 and 35.8(1)ꢁ for 4, respectively. The Nꢀ ꢀ ꢀH–C
angle is almost linear (157ꢁ for 1 and 173.5ꢁ for 3,
respectively) and the distance between N and observed
˚
A) [16]. Solvent molecules sometimes play crucial role
for the occurrence and/or strength of aurophilicity
[10,12]. However, crystals of 1–5, 7 and 9–12 do not con-
tain solvent molecules. Bates et al. [16] and Balch and
co-workers [12] have drawn attention to the change of
aurophilic interaction due to the polymorphims in Au
phosphine derivatives. Healy and co-workers [17] have
also reported the importance of cooperative effects of
weak forces in different crystal structures of the same
Au compounds. We have also reported that the appear-
ance of aurophilicity depends on the crystal polymor-
phism for simple mononuclear Au phosphine
derivatives [13]. However, other crystal systems than
those described in the present paper have not been de-
tected so far for 1 and 3. Thus 2-S-py ligand itself is
important for the strong aurophilicity in 1 and 3.
Balch et al. have indicated that there are some pre-
ferred geometrical parameters for Au–Au interaction
in a series of (AuX)2{P(CH2)nP} derivatives [12]; the
X–Au–Au–X torsional angles and X–Au–Au–Y angles
average to 90ꢁ. For the present system where the A-type
of aurophilicity is explicitly manifested, S–Au–Au–S
torsional angles are 84.1ꢁ, 120.9ꢁ, 75.3ꢁ, and 64.6ꢁ,
respectively for 1, 3, 4, and 7, P–Au–Au–P torsional an-
gles are 77.6ꢁ, 121.3ꢁ, 71.0ꢁ and 67.3ꢁ, respectively, for
this order, and S–Au–Au–P torsional angles are 99.2ꢁ,
59.7ꢁ, 104.7ꢁ and 109.0ꢁ and 114.0ꢁ, respectively, in this
order. Observed Au–Au distances for the present series
of compounds are generally shorter than those of
Balchꢀs chlorides but their trends do not hold for our
compounds.
˚
H (from the Fourier map) is 2.8(2) A [20]. These results
suggest a kind of hydrogen bond between N and H–C–
[20,21]. The lack of a hydrogen atom in an ortho posi-
tion should make it possible for 2-S-pyridine rings to
be coplanar with the C–P–Au–S backbone and small
dihedral angles for 1 and 3 are thus rationalized. In 1
and 3, the 2-S-pyridine ring and the S–Au–P–C moiety
can provide a desired flat pedestal for Nꢀ ꢀ ꢀH–C@ inter-
action mentioned above. Thus Nꢀ ꢀ ꢀH–C interaction is a
certain viable source for this coplanarity. Aurophilicity
has now been suggested to be quite sensitive to many
factors, and the reported factors are sometime contro-
versial [7,12,16,19]. Pyykko¨ has suggested that the lig-
and softness tends to reinforce the aurophilicity. The
2-S-pyridine group seems to play a similar role as a soft
ligand at experimental levels; the S group at an ortho-
position donates more electrons to Au(I) than that at
the para-position. Further experiments to support possi-
ble Nꢀ ꢀ ꢀH–C interaction are described below.
The 1H NMR spectrum of 1 in CDCl3 has shown that
four magnetically different protons of 2-S-pyridyl ligand

Table 1
Crystal data
Compound
1
2
3
4
5
6
7
8
9
10
11
12
Chemical formula
C
36H30Au2- C36H30Au2- C36H32Au2- C36H32Au2-
C38H34Au2-
P2S2
C37H34Au2- C39H36Au2-
C44H42Au2-
N2P2S2
C38H36Au2- C40H38Au2-
C24H21Au1- C25H23Au1-
N2P2S2
N2P2S2
N2P2S2
N2P2S2
1012.7
N2P2S2
1026.7
P2S2
N2P2S2
1040.7
P2S2
N1P1S1
583.4
N1P1S1
597.5
Formula weight
Crystal system
Space group
˚
a (A)
˚
b (A)
1010.7
1010.7
1012.7
1010.8
1024.7
1118.8
1038.7
Triclinic
ꢀ
P
Monoclinic
C2/c
Monoclinic
P21/n
Monoclinic
C2/c
Triclinic
ꢀ
Triclinic
ꢀ
Triclinic
ꢀ
Triclinic
ꢀ
Monoclinic
P21/n
Triclinic
ꢀ
Triclinic
ꢀ
Triclinic
ꢀ
P
P
P
P
P
P
P
16.035(2)
20.323(2)
11.264(4)
112.854(3)
114.33(1)
16.691(5)
20.645(9)
11.159(4)
16.158(1)
19.762(1)
11.214(1)
8.759(2)
9.879(2)
10.532(2)
10.4706(9)
11.636(1)
16.468(2)
70.771(2)
86.757(2)
69.131(2)
1765.9(3)
4
8.626(1)
11.207(2)
18.647(3)
93.551(3)
100.141(8)
107.408(5)
1680.5(4)
2
8.718(2)
11.637(3)
17.863(4)
92.446(3)
93.144(4)
108.415(3)
1713.4(2)
2
8.735(1)
10.073(1)
23.768(3)
9.918(1)
9.910(1)
19.098(1)
91.743(1)
88.221(1)
74.900(1)
995.7(1)
2
10.899(2)
11.888(2)
15.715(3)
107.380(3)
95.948(3)
108.741(3)
1794.8(4)
2
9.070(6)
11.309(7)
11.536(9)
79.19(6)
71.30(5)
89.61(5)
1099(1)
2
8.850(5)
14.364(5)
18.616(7)
75.90(3)
86.23(4)
81.61(4)
2269(2)
2
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
99.34(4)
90.409(3)
3792(3)
4
111.744(1)
102.447(3)
95.683(3)
3
˚
V (A )
3345.0(9)
4
3326.0(2)
4
815.9(2)
1
2080.8(5)
4
Z
Dcalc (g cmꢁ3
)
2.06
1.79
2.02
2.06
1.90
2.03
1.99
1.79
1.91
1.99
1.76
2.26
Crystal
dimension (mm3)
0.55 · 0.5
· 0.3
9.02
0.75 · 0.55
· 0.45
7.94
0.1 · 0.1
· 0.1
12.3
0.15 · 0.1
· 0.1
9.24
0.1 · 0.15
· 0.1
8.5.
0.1 · 0.1
· 0.1
1.22
0.1 · 0.15
· 0.1
8.8
0.2 · 0.15
· 0.1
7.3
0.1 · 0.1
· 0.1
11.35
0.1 · 0.1
· 0.1
8.4.
0.6 · 0.50
· 0.45
6.9
0.7 · 0.55
· 0.40
6.8
l (mm)
Diffractometer
2hmax (ꢁ)
Temperature (K)
MXC3
50
MXC3
45
MAC DIP
SMART APEX SMART APEX MAC DIP
SMART APEX SMART APEX MAC DIP
SMART APEX MXC3
MXC3
55
55
55
55
55.0
120
50.0
100
45.0
298
298
298
120
100
3558
3503
100
7660
5485
120
7681
6419
100
4900
4542
293
298
Unique reflections 2957
4954
7762
7222
4775
2412
10330
8749
7855
7316
3874
3117
5941
5279
Data reduction
2355
3045
cut off
Number of
203
227
263
205
260
406
550
235
559
501
253
293
parameter refined
R1
0.064
0.186
P
0.102
0.258
P
0.02
0.04
P
0.04
0.11
0.08
0.15
0.04
0.09
0.03
0.08
0.06
0.11
0.04
0.04
0.09
0.096
0.262
0.098
0.254
wR2
P
0.067
2
2
1=2
2
R ¼ jjF oj ꢁ jF cjj= jF oj; Rw ¼ f w½ðF 2o ꢁ F c2Þ = wðF o2 Þ ꢂ ; where w ¼ 1=½r2ððF 2oÞ þ ðapÞ þ bpÞꢂ.

S. Onaka et al. / Journal of Organometallic Chemistry 690 (2005) 57–68
65
appear as sharp signals at room temperature, suggesting
that the solid state conformation about the S-pyridyl
group is not fluxional on an NMR time scale even in a
solution. In addition, the ethylene proton resonates at
approximately 0.4 ppm lower field (d 7.64) than that
of (AuSPh)2(l2-t-dpen) [14]. Close contact between N
and H–C@ described above suggests that the lower field
shift is the result of the hydrogen bond between N and
H. If this is the case, the ethylene proton signal of 1
should be detected almost at the same position as those
of aforementioned analogues, when the hydrogen bond
formation is inhibited by blocking the N atom from this
interaction. A drop of dilute hydrochloric acid suspen-
sion into CDCl3was added to a NMR tube of 1. After
several hours standing, the mixture was subjected to
1H NMR measurements; the addition caused a signifi-
cant higher field shift of the ethylene proton (d 7.52)
with concomitant remarkable lower field shifts of
pyridine proton signals, although peaks due to phenyl
protons were left intact. The ortho-proton signal of the
2-S-pyridyl ligand was shifted from 7.37 to 7.38 (d) to
7.48, meta-proton signal(d) from 8.04 and 6.82 to 8.10
and 6.94, respectively, and the para-proton signal from
7.32 (t) to 7.43. We suspected at first that (Au–2–S–
py)(Au–Cl)(l2-t-dpen) and/or (AuCl)2(l2-t-dpen) was
yielded upon addition of HCl [14]. However, the ob-
Jeffrey has classified hydrogen bonds into three cate-
gories, that is, strong, moderate and weak [21]. The gen-
eral Nꢀ ꢀ ꢀH interactions have been well documented and
similarly classified [22]. Thaimattam et al. have reported
that 4,40-dicyanobiphenyl forms a 1:1 complex with urea
˚
via long C–Hꢀ ꢀ ꢀN interactions (2.88 and 2.83 A) and
concluded that these interactions contribute in some
measure to overall crystal and supra structural stabiliza-
tion [23]. Among many examples where pyridyl and/or
nucleotide N atoms are concerned, the observed
Nꢀ ꢀ ꢀH–C@ contact in 1 seems to be an upper limit of
weak interactions. Because of paucity of data, we do
not intend to allege that this Nꢀ ꢀ ꢀH–C@ interaction
reinforce the aurophilicity, but we propose that the find-
ings should not be vitiated.
4. Conclusion
It is worth pointing that the 2-S-pyridine group is one
of the best SR ligand to reinforce the aurophilicity for
Au(I) diphosphine derivatives with a short hydrocarbon
backbone. The 2-S-pyridine ring is almost coplanar to
the P–C@C–P skeleton. The lack of the hydrogen atom
on N makes this conformation possible and this leads to
a kind of Nꢀ ꢀ ꢀH–C@ hydrogen bond. The compactness
around the central part including Au, S, P, and the
hydrocarbon backbone should be the most important
factor to accentuate the aurophilicity.
1
served H NMR spectrum is entirely different from the
spectra of these compounds. Therefore, the observed re-
sults are interpreted in terms that the lower-field shifts of
pyridine protons are induced by the protonation of the
N atom in the 2-S-pyridine ligand and the formation
of the pyridinium salt is completed within several hours
upon addition of hydrochloric acid, because no pyridine
proton signal due to original 1 is detected. Another at-
tempt to intervene such a hydrogen bonding is a use
of pyridine as a solvent. However, such an attempt to
5. Experimental
5.1. General comments
Reactions were carried out under an argon atmos-
phere by standard Schlenk techniques. The reaction ves-
sel was covered with a piece of black cloth to shield from
room light. All diphosphine ligands except t-dpen were
purchased from Aldrich and Strem Chemicals Inc.;
t-dpen was purchased from Tokyo Kasei Co. Ltd. 2-
and 4-Pyridinethiols were also purchased from Aldrich.
4-Pyridineethanethiol was obtained from Tokyo Kasei
Co. Ltd. in a form of hydrochloride. 4-Pyridinemetha-
nethiol was synthesized according to the literature meth-
od with major revisions [24]. 4-Pyridinemethanethiol
was kept in a form of dilute THF solution, because pure
4-pyridinemethanethiol decomposes easily.
1
take a H NMR spectrum of 1 in deuterated pyridine
was hampered because of low solubility in this solvent.
We surmise that some kind of such an attractive force
is effective even in solutions and co-planarity of the eth-
ylene protons in the @CH–P group to the –S–pyridine-
ring may be a good reason to account for a lower-field
shift of this proton. Perhaps a kind of delocalized system
(Scheme 1) is constructed and a ring current produced in
these complexed rings is largely responsible for a lower
field shift of the ethylene protons in 1.
1H NMR spectra were recorded on a Varian Gemini-
2000 (300 MHz) spectrometer and 31P{1H} NMR spec-
tra were recorded at 80.984 MHz on a Varian XL-200
spectrometer. 31P{1H} NMR chemical shifts are refer-
enced to external 85% H3PO4. C, H, N analyses were
made for key compounds; characterizations of other
1
compounds were done by H NMR and single crystal
X-ray diffractions.
Scheme 1. Structural motifs for diphosphine digold complexes.

66
S. Onaka et al. / Journal of Organometallic Chemistry 690 (2005) 57–68
5.2. Synthesis of [Au(x-S-pyridine)]2(l2-t-dpen)
Calc. for C36H32Au2N2P2S2; C, 42.72; H, 3.19; N, 2.77.
Found: C, 42.47 ; H, 3.00; N 2.78%.
The synthesis of [Au(2-S-pyridine)]2(l2-t-dpen) (1) (t-
dpen = 1,2-bis(diphenylphosphino)-ethylene) described
below was a typical procedure for [Au(x-S-pyri-
dine)]2(l2-diphos) type compounds. 2-S- and/or 4-S-
pyridine group was introduced into (AuCl)2(l2-t-den)
scaffold [13,25] by substituting C5H4NSꢁ for Cl. In a
200-ml three necked round-bottom flask, a methanol
solution (40 ml) of 2-pyridinethiol (120 mg, 1.25 mmol)
and KOH (70 mg, 1.25 mmol) were placed and then a
CH2Cl2 solution (50 ml) of (Cl–Au)2(l2-t-dpen) (430
mg, 0.50 mmol) was added. The mixture was stirred at
room temperature overnight. Solvents were distilled off
by rotary-evaporator to leave a pale yellow solid. The
solid was washed with small amount of hexane, benzene
and methanol successively. The residue was extracted
with small amount of CH2Cl2 and was recrystallized
from CH2Cl2–hexane to afford pale yellow crystals of
1. Yield 330 mg, 65%. 31P NMR: d 36.2. 1H NMR
(CDCl3, 300 MHz): d 8.04 (d, 6-H in py, 2H), 7.64 (t,
18.6 Hz, HC@, 2H), 7.54–7.83 (m, PPh, 20H), 7.38-
7.37 (d, 3-H in py, 2H), 7.32 (t, 4-H in py, 2H), 6.82
(t, 2-H in py, 2H). Anal. Calc. for C36H30Au2N2P2S2:
C, 42.78; H, 2.99; N, 2.77. Found: C, 42.54; H, 2.76;
N 2.62%.
The 4-S-pyridine analogue, [Au(4-S-pyridine)]2(l2-
dppe)(4), was similarly synthesized in 71% yield. 31P
NMR: d 36.3 (s). 1H NMR (CDCl3, 300 MHz): d
8.17–8.06 (m, 2,6-Spy, 4H), 7.72–7.58 (m, o-Ph, 8H),
7.57–7.38 (m, m-Ph, p-Ph, 3,5-H in Spy, 16H), 2.73 (s,
–CH2–, 4H).
The S-phenyl analogue, [Au(S-phenyl)]2(l2-dppe) (5),
was similarly synthesized in 76% yield. 31P NMR: d 37.3
1
(s). H NMR (CDCl3, 300 MHz): d 7.73–7.55 (m, o-Ph,
m-S-Ph, 12H), 7.55–7.38 (m, m-Ph, p-S-Ph, 12H), 7.15–
6.95 (m, o-S-Ph, p-S-Ph, 6H), 2.94–2.73 (m, –CH2–C–
CH2–, 4H), 2.10–1.82 (m, C–CH2–C–, 2H).
[Au(2-S-pyridine)]2(l2-dppp) (6) Æ 1/2C6H6 (dppp =
1,3-bis(diphenyl phosphino) propane) was synthesized
1
in 83% yield. 31P NMR: d 32.1 (s). H NMR (CDCl3,
300 MHz): d 8.15–8.08 (m, 6-H in Spy, 2H), d 7.81–
7.67 (m, o-Ph, 8H), 7.50–7.35 (m, m-Ph, p-Ph, 3-H in
Spy 14H), 7.35–7.27 (m, 5-H in Spy, 2H), 6.84–6.75
(m, 4-H in Spy, 2H), 3.09–2.90 (m, CH2–C–CH2, 4H),
2.16–1.92 (m, C–CH2–C). [Au(S-phenyl)]2(l2-dppp) (7)
was similarly synthesized in 76% yield. 31P NMR: d
1
32.5 (s). H NMR (CDCl3, 300 MHz): d 7.71–7.49 (m,
o-Ph, m-S-Ph, 12H), 7.49–7.35 (m, m-Ph, p-Ph, 10H),
7.15–6.95 (m, o-S-Ph, p-S-Ph, 6H), 2.94–2.73 (m,
CH2–C–CH2, 4H), 2.10–1.82 (m, C–CH2–C). Anal.
Calc. for C37H34Au2N2P2S2 Æ 1/2C6H6; C, 45.08;
H,3.50; N, 2.63. Found: C, 45.06; H, 3.60; N, 2.60%.
The 2-S-pyridine analogue [Au(2-S-pyridine)]2(l2-
dppb) (dppb = 1,4-bis(diphenyl phosphino)butane) (8)
was similarly synthesized in 58% yield. 31P NMR: d
The 4-pyridine-S analogue, [Au(4-S-pyridine)]2(l2-t-
dpen) (2) was obtained in 45% yield. 31P NMR: d
1
35.5. H NMR (CDCl3, 300 MHz): d 8.13 (dd, 2,6-H
in py, 4H), 7.50–7.66 (m, PPh, 20H), 7.40 (dd, 3,5-H
in py, 4H), 7.25 (t, 19.2 Hz, HC@, 2H).
1
34.71 (s). H NMR (CDCl3, 300 MHz): d 8.24–8.18 (m,
6-S-py, 2H), 7.78–7.65 (m, o-Ph, 8H), 7.52–7.38 (m, m-
Ph, p-Ph, 5-H in Spy, 14H), 7.36–7.29 (m, 5-H in Spy,
2H), 6.88–6.79 (m, 4-H in Spy, 2H), 2.77–2.38 (m,
–CH2–C–C–CH2–, 4H), 1.98–1.80 (m, –C–CH2–CH2–
C–, 4H). Anal. Calc. for C38H36Au2N2P2S2; C, 43.86;
H, 3.49; N, 2.69. Found: C, 43.95; H, 3.51; N, 2.64%.
[Au(4-S-pyridine)]2(l2-dppb) (9) was similarly synthe-
sized in 72% yield. 31P NMR: d 35.1 (s). 1H NMR
(CDCl3, 300 MHz): d 8.18–8.14 (m, 2,6-S-py, 4H),
7.72–7.58 (m, o-Ph, 8H), 7.56–7.42 (m, m-Ph, p-Ph, 3,5-
H in Spy, 16H), 2.58–2.37 (m, –CH2–C–C–CH2–, 4H),
1.93–1.76 (m, –C–CH2–CH2–C–, 4H). The S-phenyl
analogue [Au(S-phenyl)]2(l2-dppb) (10) was similarly
synthesized in 74% yield. 31P NMR: d 35.10 (s). 1H
NMR (CDCl3, 300 MHz): d 7.72–7.54 (m, o-Ph, m-
S-Ph, 12H), 7.54–7.40 (m, m-Ph, p-Ph, 12H), 7.16–6.94
(m, o-S-Ph, p-S-Ph, 6H), 2.58–2.38 (m, –CH2–C–C–
CH2–, 4H), 1.95–1.75 (m, –C–CH2–CH2–C–, 4H).
5.3. Synthesis of [Au(x-S-pyridine)]2(l2-diphos)
[Au(2-S-pyridine)]2(l2-dppe) (3) (dppe = 1,2-bis(diph-
enylphosphinoethane)) was similarly synthesized as
above. 2-S- and/or 4-S-pyridine group was introduced
into (AuCl)2(l2-diphos) scaffold [13,24] by substituting
C5H4NSꢁ for Cl. To a CH2Cl2 solution (20 ml) of
(AuCl)2(l2-dppe) (86 mg, 0.1 mmol) was added 22 mg
(0.2 mmol) of 2-pyridinethiol and 400 mg (3.8 mmol) of
Na2CO3. The mixture was stirred at room temperature
overnight and the solution was concentrated to 5 ml
and to this was added 15 ml of diethylether. The mixture
was left standing at room temperature for 24 h. The
resulting yellow precipitates were collected on a frit and
washed with small amount of diethylether to afford 68
mg (67%) of [Au(2-S-pyridine)]2(l2-dppe) (3). Com-
pound 3 was recrystallized from CH2Cl2–hexane to af-
ford pale yellow crystals. 31P NMR: d 37.3 (s). 1H
NMR (CDCl3, 300 MHz): d 8.14–8.07 (m, 6-H in Spy,
2H), 7.84–7.70 (m, o-Ph, 8H), 7.53–7.40 (m, m-Ph, p-
Ph, 3-H in Spy, 14H), 7.37–7.29 (m, 5-H in Spy, 2H),
6.86–6.77 (m, 4-H in Spy, 2H), 2.85 (s, –CH2–, 4H). Anal.
5.4. Synthesis of Au{4-S-(CH2)n-pyridin}PPh3
The synthesis of Au(4-S-CH2-pyridine)PPh3 (11) de-
scribed below was a typical procedure for this type of

S. Onaka et al. / Journal of Organometallic Chemistry 690 (2005) 57–68
67
˚
compounds. To a 300 ml three necked round-bottom
flask, a CH2Cl2 solution (100 ml) of Ph3PAuCl (156
mg, 0.32 mmol) was added. Then a methanol solution
(70 ml) which contains 100 mg (0.8 mmol) of 4-pyridine-
methanethiol and 20 mg (0.36 mmol) of KOH was
dropped for 1.5 h. After the mixture was stirred at room
temperature for 3 h, the solvent was rotary-evaporated
and the resulting pale yellow solid was recrystallized
from CH2Cl2/hexane (1:1) two give very pale yellow
monochromated Mo Ka radiation (k = 0.71073 A).
Reflection data for 4, 5, 7, 8 and 10 were collected at
100 K on a Bruker SMART-APEX CCD diffractometer
with graphite-monochromated Mo Ka radiation
˚
(k = 0.71073 A); these crystals were mounted on a nylon
˚
loop. The SPring-8 BL04B2 beam line (k = 0.3282 A)
equipped with a MAC DIP-LABO imaging plate dif-
fractometer [26] was used for data collections of 3, 6
and 9 at 120 K because only small size crystals were
available for these compounds; these crystals were at-
tached on a nylon loop similarly as above. The struc-
tures of these crystals were solved by the direct
method using SIR-97 in a WINGX program package
and refined with anisotropic displacement parameters
by full-matrix least-squares with SHELXS-97 in a WINGX
program package [27]. Carbon atoms in Ph and S-py
groups for 1, 2, 11 and 12 were refined isotropically, be-
cause numbers of these atoms have a negative thermal
factors upon anisotropic refinements; crystals of these
compounds are liable to decompose during reflection
data collection for several days and the data accumu-
lated are not at a satisfactory level. The refinements were
made on F2 data and the final R and wR2 values are gi-
ven in Table 1. Tables for atomic coordinates, displace-
ment parameters, and bond-lengths and angles are
available as supplementary materials. Selected bond
lengths and angles are given in Table 2. The supplemen-
tary crystallographic data are contained in CCDC-
240099 (1), -240100 (2), -240101 (3), -240102 (4),
1
crystals of 11 in 81% yield. 31P NMR: d 37.29 (s). H
NMR (CDCl3, 300 MHz): d 8.37 (d, 2, 6-H in Spy,
2H), 7.75 (d, 3, 5-H in Spy, 2H), 7.39–7.56 (m, Ph,
15H), 4.21 (s, –CH2–, 2H).
Au{4-S-(CH2)2-pyridine}PPh3 (12) was synthesized
similarly from Ph3PAuCl (1.00 g, 2 mmol), 365 mg (2
mmol) of 4-pyridineethanethiol hydrochloride, and 175
mg (3 mmol) of KOH. Yield of 12 is 1.14 g (95%). 31P
NMR: d 36.88 (s). 1H NMR (CDCl3, 300 MHz): d
8.36 (dd,, 2,6-H in Spy, 2H), 7.53–7.44 (m, Ph, 15H),
7.13 (d, 3,5-H in Spy, 2H), 3.31 (t, S–CH2–, 2H), 3.02
(t, S–C–CH2-py, 2H).
5.5. X-ray crystallography
Crystals suitable for X-ray studies were generally
grown from CH2Cl2–hexane solutions. Selected crystals
of 1, 2, 11 and 12 were glued to the top of a fine glass rod
and the reflection data were collected at room tempera-
ture on a MAC MXC3 diffractometer with graphite
Table 2
˚
Selected bond lengths (A) and angles (ꢁ)
Compound
1
2
3
4
5
6
7
8
9
10
11
12
˚
Bond distances (A)
Au–Au
Au–S
2.986(1)
3.239(2)
2.29(1)
2.294 (9)
2.255(9)
2.258(8)
1.74(4)
1.73(3)
1.77(3)
1.84(3)
1.82(3)
1.83(3)
1.88(3)
1.84(3)
2.9679(2)
2.3087(4)
3.0840 (6)
2.296(5)
2.310(3)
2.259(3)
2.254(2)
1.724(5)
1.758(4)
1.816(9)
1.799(4)
1.824(2)
1.826(3)
1.791(3)
1.847(4)
3.1081(5)
2.321(2)
2.320(2)
2.262(2)
2.259(2)
1.753(7)
1.73(1)
3.1389(5)
2.321(2)
2.312(2)
2.273(2)
2.259(2)
1.774(8)
1.796(7)
1.834(7)
1.807(7)
1.822(7)
1.838(7)
1.829(8)
1.820(6)
3.626(1)
2.311(1)
2.314(1)
2.268(1)
2.269(1)
1.751(4)
1.745(4)
1.819(3)
1.821(4)
1.812(4)
1.811(4)
1.826(4)
1.822(4)
3.0926(5)
2.311(2)
2.291(3)
2.259(2)
2.263(2)
1.771(6)
1.59(1)
2.312(4)
2.260(4)
1.73(2)
2.296(5)
2.253(2)
1.756(7)
2.300(3)
2.248(3)
1.74(2)
2.294(8)
2.265(6)
1.63(4)
2.298(4)
2.292(4)
2.258(4)
2.276(4)
1.90(2)
1.79(2)
1.86(2)
1.84(1)
1.82(1)
1.81(1)
1.83(2)
1.87(1)
Au–P
S–C
2.2629(4)
1.754(2)
P–C
1.80(2)
1.83(2)
1.79(1)
1.819(1)
1.812(1)
1.814(1)
1.815(5)
1.810(5)
1.797(6)
1.829(7)
1.841(7)
1.805(7)
1.806(9)
1.795(8)
1.809(7)
1.82(2)
1.81(1)
1.84(1)
1.830(6)
1.808(4)
1.817(7)
1.819(5)
1.816(7)
1.818(8)
1.79(2)
1.75(3)
1.85(2)
Bond angles (ꢁ)
P–Au–S
Au–S–C
Au–P–C
176.8(1)
174.9(4)
172.8(4)
102(2)
176.80 (1)
108.74(4)
174.91(7)
105.5(2)
172.3(1)
170.6(1)
105.3(2)
99.3(2)
173.36(7)
172.16(7)
105.2(2)
101.1(3)
114.0(3)
113.7(2)
114.3(3)
112.2(2)
112.2(2)
115.8(2)
94.40(5)
87.36(6)
91.47(5)
100.05(5)
171.26(6)
167.63(6)
108.2(2)
96.2(2)
175.9(1)
101.1(5)
178.32(4)
178.33(4)
108.9(1)
109.0(1)
115.9(1)
113.4(1)
111.0(1)
116.2(1)
111.0(1)
113.6(1)
174.73(5)
175.05(8)
105.7(2)
112.3(5)
113.6(2)
113.4(2)
110.4(2)
116.6(3)
113.1(2)
110.1(2)
84.26(4)
78.01(7)
98.87(4)
106.94(4)
175.6(2)
120(3)
178.5(2)
175.3(2)
102.3(6)
103.8(7)
109.0(4)
114.4(5)
114.8(5)
113.2(5)
113.6(4)
114.5(5)
108.9(6)
105(1)
109.4(5)
118.9(5)
118.5(5)
114(1)
107.98(4)
115.6(4)
118.29(4)
114.5(2)
112.4(2)
113.1(2)
108.7(3)
117.1(2)
117.2(1)
109.7(1)
114.5(2)
118.0(1)
80.13(8)
79.85(8)
105.27(6)
106.91(6)
103.2(1)
112.8(3)
112.6(2)
116.3(2)
113.9(2)
115.6(2)
111.4(2)
92.02(4)
94.30(5)
96.70(5)
98.02(5)
108.2(4)
109.5(4)
118.1(4)
114.2(3)
111.9(7)
114.0(7)
112(1)
116(1)
111(1)
112.8(9)
110(1)
115(1)
Au–Au–S
Au–Au–P
77.6(1)
85.3(3)
73.8(2)
101.6(2)
77.86(3)
73.9(1)
102.81(9)
102.61(4)

68
S. Onaka et al. / Journal of Organometallic Chemistry 690 (2005) 57–68
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This research was funded by Grants-in Aid for Scien-
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Scientific research (No. 14540514) from the Ministry
of Education, Science, Sports and Culture, Japan. The
synchrotron radiation experiment was performed
at the BL04B2 beamline in the SPring-8 with the
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