Solid-state luminescence and crystal structures of novel gold(i) benzenethiolate complexes

Article abstract of DOI:10.1039/b006572m

A series of mononuclear bis(benzenethiolato)gold(i) complexes, [n-Bu4N][Au(SC6H4R)2] [R = H (1), o-Me (2), o-OMe (3), o-Cl (4), m-Me (5), ni-OMe (6), i-Cl (7),/;-Me (8),/?-OMe (9) orp-Cl (10)] showed luminescence in the solid state at room temperature. The emission maxima ranged from 438 (blue emission) to 529 nm (green emission). The luminescence of these complexes is affected by substituent effects: electron-donating substituents (R = Me or OMe) on the benzene rings tend to shift the emission maxima toward shorter wavelengths, but the electron-withdrawing substituents (R = Cl) make the emission maxima shift toward longer wavelengths when compared to the maximum of the non-substituted species. This suggests that the luminescence properties could come from excited states due to a metal-to-ligand charge-transfer (MLCT) or ligand-centred (LC) transition. Complexes 2, 4, and 7 show normal linear S-Au-S geometries but exhibit no gold-gold interactions owing to the steric hindrance of the bulky counter cations, [n-Bu4N]⁺, which prevent the approach of two neighboring gold atoms. Both 2 and 4 show asymmetric configurations of the two thiolate ligands. On the other hand, 7 shows a completely symmetric configuration, where the gold atom is positioned at a center of symmetry. The Royal Society of Chemistry 2000.

Full text of DOI:10.1039/b006572m

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Solid-state luminescence and crystal structures of novel gold(I)
benzenethiolate complexes
Seiji Watase,a Masami Nakamoto,*a Takayuki Kitamura,b Nobuko Kanehisa,c Yasushi Kaic
and Shozo Yanagida*b
a Osaka Municipal Technical Research Institute, Morinomiya, Joto-ku, Osaka 536-8553,
Japan. E-mail: nakamoto@omtri.city.osaka.jp
b Material and Life Science, Graduate School of Engineering, Osaka University, Suita,
Osaka 565-0871, Japan. E-mail: yanagida@chem.eng.osaka-u.ac.jp
c Department of Materials Chemistry, Graduate School of Engineering, Osaka University,
Suita, Osaka 565-0871, Japan. E-mail: kai@chem.eng.osaka-u.ac.jp
Received 9th August 2000, Accepted 23rd August 2000
First published as an Advance Article on the web 19th September 2000
A series of mononuclear bis(benzenethiolato)gold() complexes, [n-Bu4N][Au(SC6H4R)2] [R = H (1), o-Me (2),
o-OMe (3), o-Cl (4), m-Me (5), m-OMe (6), m-Cl (7), p-Me (8), p-OMe (9) or p-Cl (10)] showed luminescence in
the solid state at room temperature. The emission maxima ranged from 438 (blue emission) to 529 nm (green
emission). The luminescence of these complexes is affected by substituent effects: electron-donating substituents
(R = Me or OMe) on the benzene rings tend to shift the emission maxima toward shorter wavelengths, but the
electron-withdrawing substituents (R = Cl) make the emission maxima shift toward longer wavelengths when
compared to the maximum of the non-substituted species. This suggests that the luminescence properties could come
from excited states due to a metal-to-ligand charge-transfer (MLCT) or ligand-centred (LC) transition. Complexes 2,
4, and 7 show normal linear S–Au–S geometries but exhibit no gold–gold interactions owing to the steric hindrance
of the bulky counter cations, [n-Bu4N]ϩ, which prevent the approach of two neighboring gold atoms. Both 2 and 4
show asymmetric configurations of the two thiolate ligands. On the other hand, 7 shows a completely symmetric
configuration, where the gold atom is positioned at a center of symmetry.
of a bulky tetra-n-butylammonium cation [n-Bu4N]ϩ, which
Introduction
may prevent gold–gold interaction in the solid state, and (iii)
Much attention has been paid to the photophysical properties
the ease of introduction of electron-donating or -withdrawing
and photochemistry of gold() complexes with the closed shell
substituents on the benzenethiolate to study substituent effects
on the luminescence.
In this paper we report the solid-state luminescence of a
series of bis(benzenethiolato)gold() complexes, [n-Bu4N][Au-
(SC6H4R)2] [R = H (1), o-Me (2), o-OMe (3), o-Cl (4), m-Me
(5), m-OMe (6), m-Cl (7), p-Me (8), p-OMe (9) or p-Cl (10)] and
the crystal structures of 2, 4, and 7 with no gold–gold inter-
actions in the crystals. All the complexes luminesce in the solid
electronic structure [Xe]4f145d10. Since such gold(I) complexes
exhibit intra- and/or inter-molecular d10–d10 interactions and
these may be an important factor for the luminescent behavior
due to the metal-centered Au(5d)→Au(6p) transition, the
preparation of polynuclear gold(I) complexes with gold–gold
interactions has been conducted in the course of luminescence
studies.1–12 However, the luminescence of the binuclear gold()
thiolate complex [Au2(p-tc)2(dppe)] [p-tc = p-toluenethiolate;
state and also exhibit characteristic substituent effects on the
luminescence, suggesting an MLCT or LC transition rather
than an LMCT one.
dppe = 1,2-bis(diphenylphosphino)ethane]13 and mononuclear
gold() thiolate complexes [Au(SR)(PPh3)]14–17 and [Au(SR)-
(TPA)] (TPA = 1,3,5-triaza-7-phosphaadamantanetriylphos-
phine)15 has recently been assigned as arising from an
S(π)→Au(6p) LMCT excited state. In addition, a binuclear
gold() complex [n-Bu4N]2[Au2(i-MNT)2] (i-MNT = 1,1-di-
cyanoethylene-2,2-dithiolate)18 and a trinuclear gold com-
plex[Au(PEt3)2][Au(AuPEt3)2(i-MNT)2]19 with a S–Au–S unit
exhibited excited states as a result of S(π)→Au(6p) LMCT
absorptions, giving luminescence. Those papers pointed out
that the LMCT excited state originating from the S–Au–S unit
is important for the luminescence, while the existence of π elec-
trons of the phosphine ligand and intra- and/or inter-molecular
gold–gold interactions may make it more complicated to
estimate the contribution of the thiolate ligand to the lumin-
escence behavior of those gold() thiolate complexes. Recently,
we found that a series of mononuclear tetra-n-butylammonium
bis(benzenethiolato)gold() complexes [n-Bu4N][Au(SR)2] show
solid-state luminescence. This type of complex offers an ideal
luminescent gold system in terms of the following points: (i) the
absence of phosphine ligands with π electrons, (ii) the presence
Results and discussion
Luminescence
The present bis(benzenethiolato)gold() complexes except
complex 4 (luminesces at 77 K) show bright luminescence in
the solid state at room temperature, as depicted in Fig. 1. The
solid-state absorption (KBr method), excitation, and emission
wavelengths of 1–10 are summarized in Table 1. The solid-state
absorption and excitation spectra of 7 are shown in Fig. 2.
Complex 7 displays broad and intense absorption in the range
250 to 350 nm and the maximum is at 292 nm (ε 18000 dm3
molϪ1 cmϪ1), while there appear no significant absorptions at
wavelengths greater than 350 nm. All other gold() thiolate
complexes also afford similar absorptions in the same region.
In the literature,16 absorption of [AuX(PR3)] (R = Ph or Et;
X = -cysteinate or thiomalate) at ca. 290 and 360 nm are
assigned to S→Au charge-transfer transitions on the basis of
DOI: 10.1039/b006572m
J. Chem. Soc., Dalton Trans., 2000, 3585–3590
This journal is © The Royal Society of Chemistry 2000
3585

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Table 1 Luminescence data of bis(benzenethiolato)gold() complexes
Absorptiona
Excitationc
λmax/nm
Emissionc
λmax/nm
Complex
λmax/nm (ε)b
1 [n-Bu4N][Au(SC6H5)2]
287 (19000)
285 (17000)
280 (14000)
290 (18000)
287 (17000)
283 (17000)
292 (18000)
286 (16000)
283 (19000)
296 (19000)
350
336
342
501
469
450
2 [n-Bu4N][Au(SC6H4Me-o)2]
3 [n-Bu4N][Au(SC6H4OMe-o)2]
4 [n-Bu4N][Au(SC6H4Cl-o)2]
5 [n-Bu4N][Au(SC6H4Me-m)2]
6 [n-Bu4N][Au(SC6H4OMe-m)2]
7 [n-Bu4N][Au(SC6H4Cl-m)2]
8 [n-Bu4N][Au(SC6H4Me-p)2]
9 [n-Bu4N][Au(SC6H4OMe-p)2]
10 [n-Bu4N][Au(SC6H4Cl-p)2]
No luminescence
326
353
386
370
355
367
482
480
512
489
438
529
a Solid-state absorption spectra were measured in KBr. b Molar absorption coefficient (dm3 molϪ1 cmϪ1) calculated from the volume and thickness
of the KBr disk. c Solid-state excitation and emission spectra were measured at 298 K.
Fig. 3 Solid-state excitation and emission spectra of complexes 8–10.
complexes to those of [Au(PR3)(SC6H4Me-p)] (R = Me or Ph)
may lead to the assignment of the intense 290 nm absorption
bands of the present complexes mainly as IL transitions of the
thiolate ligands.
Complex 7 shows solid-state luminescence (λem = 512 nm)
upon excitation at 386 nm at room temperature. Similarly,
intense emissions ranging from 438 to 529 nm were recorded for
the other complexes upon excitation at 326–386 nm, respec-
tively, as shown in Table 1. In the region of excitation there exist
Fig. 1 Photograph of the luminescence of [n-Bu4N][Au(SC6H4R)2]
[R = H(1), o-Me (2), o-OMe (3), o-Cl (4), m-Me (5), m-OMe (6), m-Cl
(7), p-Me (8), p-OMe (9) or p-Cl (10)] excited by the xenon lamp.
no obvious absorptions for the present complexes in the solid
state (Fig. 2) and in solution. However, at higher concentrations
in acetonitrile solution (2.4 × 10Ϫ2 mol dmϪ3), quite weak
shoulders (ε 10 dm3 molϪ1 cmϪ1) appear to lower energy (350–
420 nm), the wavelengths of which are compatible with those of
the observed excitation.† Thus, it suggests that the excitation of
the present complexes could come from an intrinsic forbidden
transition in this region rather than the stronger high-energy
transitions at ca. 290 nm.
The solid-state excitation spectra of complexes 8–10 in Fig. 3
were observed in the narrow range from λex = 355 to 370 nm.
Such behavior is suggestive of the excitation based on the same
origin in complexes 8–10. On the other hand, the emission of
these complexes showed very large Stokes shifts (>5000 cmϪ1),
and the emission maxima appeared over a wide range from
Fig. 2 Solid-state absorption (—) and excitation (–––) spectra of
complex 7.
λem = 438 nm (blue emission) to 529 nm (green emission) in
spite of the narrow range of the excitation wavelengths. Similar
results were obtained for complexes 1–7 (Table 1). Large Stokes
shifts of 83–177 nm (5300–9900 cmϪ1) between the excitation
UV-visible and CD spectra and SCF-MO calculations. Anal-
ogous gold() complexes containing the toluenethiolate ligand,
[Au(PR3)(SC6H4Me-p)] (R = Me or Ph) and [Au2(dppm)-
and emission wavelengths for each complex suggest that a large
distortion occurs in the excited state, based on the electronic
(SC6H4Me-p)2] [dppm = bis(diphenylphosphino)methane], were
and/or steric effect of the substituents on the benzene rings.
reported to show absorptions at 260 and 280 nm, which are
mainly composed of intraligand (IL) transitions of p-toluene-
thiolate with additional charge transfer or metal-centered
These results prompted us to study substituent effects on the
emission spectra.
transitions in the region 300 to 330 nm on the basis of
† Despite the observation of weak transitions responsible for the lumi-
nescence at higher concentrations in solution, all the complexes are not
Gaussian band spectral fitting.17 Thus, the similarities in peak
positions and absorptivities of the present gold() thiolate
3586 J. Chem. Soc., Dalton Trans., 2000, 3585–3590
luminescent in solution at room temperature.

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Compared to the emission maximum (λem = 501 nm) of the
non-substituted benzenethiolate complex 1, electron-donating
substituents such as methyl or methoxy on the thiolate ligands
cause the emission maxima to shift 12–63 nm toward shorter
wavelengths (blue shift). On the other hand, the electron-
withdrawing chloro group causes the emission maximum to
shift 19–28 nm to longer wavelengths (red shift). Furthermore,
the emission maxima shift to the longer wavelengths in the
order OMe < Me < (H) < Cl in spite of the ortho, meta, and
para positions of substituents. This reveals that the electronic
property of the substituent reflects the emission behavior
induced by the same excitation process for all the complexes
described. It should be noted that the difference of the emission
maxima, ∆λem = 91 nm (3900 cmϪ1), in the series of para
substituted derivatives 8–10 is much greater than the values
for the ortho [∆λem = 51 nm (2200 cmϪ1)] and meta derivatives
[∆λem = 40 nm (1600 cmϪ1). In practice, complex 9 with
p-OMe and complex 10 with p-Cl show blue and yellowish
green emission, respectively (Fig. 1). Such a color change is
reasonably explained by the resonance effect of the benzene
ring, which amplifies the normal electronic effects of sub-
stituent on the thiolate ligand.
Fig. 4 An ORTEP26 view of complex 2. Thermal ellipsoids (in all
cases) are drawn at the 30% probability level.
It is well known that substituents on a ligand affect the
excitation and emission spectra due to an LMCT transition;20
the electron-withdrawing substituents of previous reported
gold() phosphine thiolate complexes, [Au(SR)(TPA)] (SR =
SC6H4X; X = H, OMe or Cl), cause a blue shift of the emission
energy compared to that of the unsubstituted one, and electron-
donating substituents and/or the formation of intermolecular
gold–gold interactions result in a red shift.15 In addition,
changing a p-toluenethiolate (p-tc) ligand of [Au2(p-tc)2(dppe)]
to the more electron donating propanedithiolate ligand
also causes a red shift in the emission energy.13 However, the
opposite trend of the substituent effects on the excitations and
emissions was observed in this study as described above. Such
a substituent dependence of the emission rules out LMCT
processes, although the previously reported gold() thiolate
complexes luminesce due to LMCT transitions.13–19,21 The
metal-centered transition arising from the gold–gold contacts
can also be disregarded, since complexes 2, 4, and 7 form no
gold–gold interactions in the crystals as described in the section
Crystal structures. Therefore, the possible sources of excitations
in this work may be a metal-to-ligand charge transfer transition
from gold (5d) to ligand (π*) or a ligand-centered (LC) transi-
tion from sulfur (non-bonding 3p) to the benzene ring (π*) of
the benzenethiolate ligand.
Fig. 5 An ORTEP view of complex 4.
Fig. 6 An ORTEP view of complex 7.
by single crystal X-ray diffraction. Selected bond lengths and
angles are listed in Table 2.
The anionic part of complex 2 contains an asymmetric struc-
ture as shown in Fig. 4. Complex 2 shows a linear S–Au–S
geometry with the angle S(1)–Au(1)–S(2) 172.7(1)Њ, which is
comparable to values in previously reported bis(thiolato)gold()
complexes ranging from 175.11(5) to 178.8(2)Њ.27–30 The two
Au–S bond lengths are slightly different from each other
[2.292(9) and 2.256(8) Å], but lie in the normal range for mono-
nuclear complexes of this type [2.251(6)–2.288(4) Å].27–30 The
two S–C bond lengths [1.85(2) and 1.71(2) Å] correspond
to a single bond (1.82 Å).31 The gold atoms in neighboring
molecules are separated by 8.492 Å and there exists no
gold–gold interaction in the crystal of complex 2. This result
is explained by the steric hindrance of the bulky tetra-n-
butylammonium cation (see below). The Au(1)–S(1)–C and
Au(1)–S(2)–C bond angles are 108.8(8) and 111.8(8)Њ, respec-
tively, and the two thiolate ligands are located asymmetrically
(Fig. 4).
The X-ray analysis of complex 4 with chloro-substituent at
the ortho position of the benzene ring gave similar results
regarding the basic S–Au–S moiety and the asymmetric con-
figuration of the thiolate ligand as shown in Fig. 5. On the other
hand, complex 7 shows a completely symmetric structure with
S(1)–Au(1)–S(1*) 180.0Њ, where the gold atom in the anionic
part of the complex is located at a crystallographic center of
symmetry and the two benzenethiolate planes are parallel to
each other (Fig. 6). This is the first example of a bis(thiolato)-
gold() complex with a completely symmetric structure.
Gold() centers in the present bis-thiolate complexes may
have more electron-rich circumstances than those of the
gold() phosphine thiolate complexes, inducing elevation of
the metal orbitals level so as to make the π* orbital of the
ligand an acceptor.21 Thus, the luminescent behavior of
the present complexes may reasonably be explained by an
MLCT excitation; an electron-withdrawing substituent on the
ligand lowers the ligand orbitals (π*), which may result in
a red shift of the emission. Conversely, an electron-donating
substituent may cause a blue shift of the emission. On the
other hand, an LC transition is another candidate, because the
emission is also expected to occur from a π* excited state.
Therefore, the emission origin of bis(benzenethiolato)gold()
complexes may provisionally be assigned to an MLCT or
LC transition. Furthermore, the weakness of the absorption
process does suggest a spin-forbidden excited state such as
3
3MLCT or LC being responsible, which are induced by the
relativistic effect of the heavy gold atom,9,22–25 but this is
tentative.
Crystal structures
The crystal structures of the complexes [n-Bu4N][Au(SC6H4-
R)2] [R = o-Me (2), o-Cl (4), or m-Cl (7)] have been determined
J. Chem. Soc., Dalton Trans., 2000, 3585–3590
3587

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In spite of the difference of the symmetry in the ligand con-
figurations, the crystal packing diagrams of these complexes
show the insertion of tetra-n-butylammonium cations into
the arrangement formed by the anionic parts. Based on these
clear-cut crystal packings, the steric hindrance of the bulky
counter cation, [n-Bu4N]ϩ, apparently prevents the formation
of intermolecular gold–gold interactions as we expected. Thus,
the crystal structures of these complexes 2, 4, and 7 exclude
solid-state luminescence based on metal-centered transitions
derived from gold–gold interactions for the present luminescent
complexes.
Table 2 Selected bond lengths (Å) and angles (Њ) for complexes 2, 4
and 7
o-Me (2)
o-Cl (4)
m-Cl (7)
Conclusion
Mononuclear bis(benzenethiolato)gold() complexes 1–10 have
been prepared. Luminescent properties of the present d10-
gold() complexes in the solid state at room temperature are
characterized by MLCT or LC transitions. The substituents on
the benzene rings shift the emission maxima toward longer
wavelengths in the order MeO < Me < (H) < Cl. In the case of
para substituted derivatives, the resonance effect of the benzene
ring as well as the electronic effect of the substituent on the
thiolate ligand reflect the emission behavior. Ligand control
Au(1)–S(1)
Au(1)–S(2)
S(1)–C
S(2)–C
Au ؒ ؒ ؒ Au
2.292(9)
2.256(8)
1.85(2)
1.71(2)
8.492(1)
2.282(12)
2.284(12)
1.73(3)
1.78(3)
8.562(3)
2.288(2)
1.766(8)
8.348(2)
S–Au(1)–S
Au(1)–S(1)–C
Au(1)–S(2)–C
172.7(1)
108.8(8)
111.8(8)
172.1(2)
109.3(9)
110.6(10)
180.0
108.9(3)
Table 3 Analytical data for bis(benzenethiolato)gold() complexes
Found (Calc.)
Yield
Far-IR
Complex (%)
mp/ЊC
%C
%H
%N
(300–700 cmϪ1
)
1H NMR (δ)
13C-{1H} NMR(δ)
1
2
3
4
5
74
78
73
64
72
66.5–67.5
50.89
(51.13)
6.91
(7.05)
2.15
(2.13)
429, 478, 696
0.92 (t, 12H), 1.33 (m, 13.7, 19.7, 24.0, 58.8, 122.2,
8H), 1.45 (m, 8H), 3.06 127.6, 131.9, 144.9
(t, 8H), 6.88 (t, 2H),
6.99 (t, 4H), 7.60 (d,
4H)
91.5–92.5
98.0–99.5
52.24
(52.54)
7.07
(7.35)
2.06
(2.04)
371, 391, 439,
454, 554, 676
0.92 (t, 12H), 1.33 (m,
13.7, 19.7, 22.5, 24.0, 58.8,
8H), 1.43 (m, 8H), 2.41 122.4, 124.7, 129.4, 134.0,
(s, 6H), 3.04 (t, 8H),
6.81 (m, 4H), 6.98 (d,
2H), 7.98 (d, 2H)
137.8, 144.2
49.92
(50.20)
6.92
(7.02)
2.03
(1.95)
372, 421, 452,
501, 575, 679
0.92 (t, 12H), 1.35 (m,
13.7, 19.7, 24.0, 55.8, 58.9,
8H), 1.52 (m, 8H), 3.15 110.5, 119.8, 123.2, 133.2,
(t, 8H), 3.84 (s, 6H),
6.67 (m, 4H), 6.85 (t,
2H), 8.03 (d, 2H)
135.2, 158.1
105.5–106.5 46.05
5.89
(6.10)
2.00
(1.93)
336, 436, 448,
472, 488, 660
0.91 (t, 12H), 1.33 (m,
13.7, 19.7, 24.0, 58.9, 123.4,
(46.28)
8H), 1.50 (m, 8H), 3.10 125.4, 129.1, 134.1, 135.3,
(t, 8H), 6.80 (t, 2H),
6.91 (t, 2H), 7.18 (d,
2H), 8.10 (d, 2H)
143.9
71.5–73.0
52.30
(52.54)
7.39
(7.35)
2.08
(2.04)
342, 418, 430,
440, 525, 679,
693
0.91 (t, 12H), 1.32 (m,
13.7, 19.7, 21.4, 24.0, 58.7,
8H), 1.45 (m, 8H), 2.19 123.1, 127.5, 129.0, 132.6,
(s, 6H), 3.07 (t, 8H),
6.67 (d, 2H), 6.88 (t,
2H), 7.38 (d, 2H), 7.43
(s, 2H)
137.0, 144.5
6
7
75
80
69
77
48
43.0–45.0
69.5–70.5
87.0–88.0
64.0–65.5
67.0–68.0
49.78
(50.20)
7.01
(7.02)
2.01
(1.95)
356, 382, 426,
445, 566, 590,
684
0.93 (t, 12H), 1.34 (m,
8H), 1.48 (m, 8H), 3.10 108.3, 117.1, 124.7, 128.2,
(t, 8H), 3.71 (s, 6H),
6.44 (d, 2H), 6.90 (t,
2H), 7.20 (m, 4H)
0.93 (t, 12H), 1.34 (m,
8H), 1.48 (m, 8H), 3.06 128.7, 130.0, 131.0, 133.0,
(t, 8H), 6.84 (d, 2H),
6.93 (t, 2H), 7.44 (d,
2H), 7.57 (s, 2H)
0.92 (t, 12H), 1.33 (m,
8H), 1.45 (m, 8H), 2.21 128.4, 131.3, 131.8, 140.8
(s, 6H), 3.08 (t, 8H),
6.80 (d, 4H), 7.47 (d,
4H)
0.93 (t, 12H), 1.34 (m,
8H), 1.48 (m, 8H), 3.10 113.5, 132.8, 134.9,156.1
(t, 8H), 3.71 (s, 6H),
6.60 (d, 4H), 7.47 (d,
4H)
13.7, 19.7, 24.0, 55.1, 58.8,
146.3, 158.9
46.16
(46.28)
6.05
(6.10)
1.94
(1.93)
301, 395, 420,
433, 443, 663,
679
13.7, 19.8, 24.0, 58.8, 122.3,
147.5
8
52.50
(52.54)
7.31
(7.35)
2.12
(2.04)
388, 395, 407,
413, 489,
495, 626
13.7, 19.7, 20.8, 24.0, 58.8,
9
49.85
(50.20)
6.96
(7.02)
2.07
(1.95)
334, 378, 399,
513, 625, 638
13.7, 19.8, 24.1, 55.4, 58.8,
10
46.02
(46.28)
5.95
(6.10)
2.06
(1.93)
485, 494, 541
0.95 (t, 12H), 1.36 (m, 13.7, 19.8, 24.0, 58.9, 127.5,
8H), 1.51 (m, 8H), 3.10 127.9, 133.0, 143.3
(t, 8H), 6.96 (d, 4H),
7.52 (d, 4H)
3588
J. Chem. Soc., Dalton Trans., 2000, 3585–3590

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Table 4 Crystal data, data collection, and structure refinement for complexes 2, 4 and 7
o-Me (2)
o-Cl (4)
m-Cl (7)
Chemical formula
Formula weight
C30H50AuNS2
685.82
C28H44AuCl2NS2
726.65
C28H44AuCl2NS2
726.65
Crystal system
Space group
a/Å
b/Å
Monoclinic
Cc (no. 9)
14.222(2)
13.923(2)
16.953(2)
109.17(1)
3171(1)
4
Monoclinic
Cc (no. 9)
14.191(3)
13.549(5)
17.109(3)
108.68(1)
3116(1)
4
Monoclinic
C2/c (no. 15)
23.427(4)
8.938(4)
16.696(4)
118.01(1)
3086(1)
4
c/Å
β/Њ
V/Å3
Z
T/ЊC
23.0
48.05
3773
3631
23.0
50.60
3723
3566
23.0
51.08
3624
3542
µ(Mo-Kα)/cmϪ1
No. of measured reflections
No. of unique reflections
Rint
0.048
0.112
0.026
R (Rw)
0.040 (0.025)
0.080 (0.035)
0.035 (0.029)
for the present bis(benzenethiolato)gold() complexes has
effected a color change of the emission. Complexes 2, 4, and 7
crystallize in the monoclinic space groups Cc(no. 9), Cc(no. 9)
and C2/c(no. 15), respectively. All these complexes include
normal linear S–Au–S geometries, but exhibit no gold–gold
interactions owing to the steric hindrance of the bulky tetra-n-
butylammonium counter cations.
JEOL JNM-EX270 Spectrometer in CDCl3 by the use of
tetramethylsilane as an internal standard, far-infrared spectra
from KBr pellets on a Perkin-Elmer spectrum GX-I0 FT-IR
system, UV-Visible absorption spectra on a Shimadzu UV-
265FW spectrophotometer and emission and excitation spectra
on a Shimadzu RF-5000 spectrofluorophotometer equipped
with an OXFORD DN1754 cryostat and an ITC4 intelligent
temperature controller using a xenon lamp as the excitation
source.
Experimental
All experiments were carried out under a nitrogen atmosphere
by using standard Schlenk techniques. Commercially available
tetrachloroauric acid, HAuCl4ؒ4H2O, and benzenethiols were
used without further purification. Triethylamine was purified
by distillation. Tetrahydrofuran (THF) as a reaction solvent
was distilled over CaH2 under a nitrogen atmosphere before use.
Tetra-n-butylammonium dibromoaurate(), [n-Bu4N][AuBr2],
was prepared by the literature method.32
Crystallography
Colorless single crystals of the complexes 2, 4, and 7 were
mounted on glass fibers with epoxy resin. Intensity data were
collected on a Rigaku AFC-5R four-circle diffractometer with
graphite-monochromated Mo-Kα radiation and the ω–2θ scan
mode. They were corrected for decay and Lorentz-polarization
effects, and empirical absorption corrections were made based
on the φ scans. The structures were solved by direct methods34
and expanded using Fourier techniques.35 The non-hydrogen
atoms were refined anisotropically, while atoms C(1) and C(11)
of complex 4 were refined isotropically. Hydrogen atoms were
placed in calculated positions (C–H 0.95 Å) but not refined.
The final cycle of full-matrix least-squares refinement was
based on observed reflections and variable parameters. All cal-
culations were performed using the TEXSAN crystallographic
software package.36
Syntheses
The bis(benzenethiolato)gold() complexes, 1–10 were prepared
by a modification of the literature method;32 [n-Bu4N][AuBr2]
was allowed to react with two equivalents of the corresponding
benzenethiols ArSH in the presence of triethylamine as a
base,14 (eqn. 1). All the complexes were readily isolated in high
[n-Bu4N][AuBr2] ϩ 2 ArSH ϩ 2 Et3N →
[n-Bu4N][Au(SAr)2] ϩ 2 Et3NHBr (1)
CCDC reference number 186/2155.
See http://www.rsc.org/suppdata/dt/b0/b006572m/ for crys-
tallographic files in .cif format.
yields (Table 3) and can be crystallized from methanol to yield
colorless crystals. The resulting single crystals of the complexes
2, 4, and 7 were found suitable for X-ray crystallographic
analysis.
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