A monomeric gold(I) carbanion complex with an uncoordinated thio-ether: [2-(methyl-sulfanyl)-phenyl](triphenyl-phosphine)gold(I)

Article abstract of DOI:10.1107/S0108270109017831

The title compound, [Au(C₇H₇S)(C₁₈H ₁₅P)], is conformationally chiral and crystallizes from benzene-hexane as individually enantio-pure crystals. This mononuclear compound has the Au^I atom linearly bo

Full text of DOI:10.1107/S0108270109017831

metal-organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
nescence are enhanced by the heavy gold centre (spin-orbit
coupling) attached to a variety of organic molecules such as
pyrene (Heng et al., 2007), phenyls, heteroaromatic rings
(Wong et al., 2007) and alkynyls (Yam et al., 2003) in mono-
nuclear (King et al., 1992) and in polynuclear complexes
(Hong et al., 1994; Rios et al., 2008).
ISSN 0108-2701
A monomeric gold(I) carbanion
complex with an uncoordinated
thioether: [2-(methylsulfanyl)phenyl]-
(triphenylphosphine)gold(I)
Doris Y. Melgarejo, Gina M. Chiarella and John P.
Fackler Jr*
Department of Chemistry, Texas A&M University, PO Box 3255, College Station,
TX 77842-3255, USA
Correspondence e-mail: fackler@mail.chem.tamu.edu
Received 26 February 2009
Accepted 12 May 2009
Online 11 July 2009
Compound (I) is the first example of gold(I) attached to a
thiomethyl aromatic carbanion. Even though the ortho thio
unit on the ring could bond to AuI to produce a four-
membered chelate ring, the long Au1ꢁ ꢁ ꢁS1 distance of
The title compound, [Au(C7H7S)(C18H15P)], is conformation-
ally chiral and crystallizes from benzene–hexane as individu-
ally enantiopure crystals. This mononuclear compound has the
AuI atom linearly bound to a triphenylphosphine P atom and
to a phenyl C atom of a 2-(methylsulfanyl)phenyl group. The
angle at the AuI atom is 175.9 (2)ꢀ. The linear ligand
coordination about the AuI atom has geometric parameters
inside the remarkably narrow range found for gold complexes
bound by a phosphine ligand and by the ortho-C atom of a
substituted phenyl group. This is the first example of gold(I)
attached to a methylsulfanyl aromatic carbanion.
˚
3.246 (3) A shows that this does not happen. Connectivity of S
to Au of a neighbouring molecule is apparently hindered by
the phenyl rings of the phosphine, which obviate any auro-
˚
philic interactions [Auꢁ ꢁ ꢁAu = 6.986 (4) A]. The propeller
organization of the phenyl rings on the phosphine lowers the
symmetry of the molecule (with no improper rotations),
making it chiral.
From what is expected to be a racemic mixture of the
product, only one of the two conformational enantiomers is
present in the crystal structure (Fig. 1), so the crystalline
Comment
Gold carbanion connections are strong, as revealed by struc-
tural (Schmidbaur, 1995) and theoretical energy studies
(Dargel et al., 1999). However, establishing such bonds usually
demands reactive carbon precursors (organolithium or
Grignard reagents) (Fernandez et al., 2004) with some
reduction of AuI to Au0. This inconvenience has prompted the
search for more efficient procedures to generate Au—C
bonds. Partyka et al. (2009), using boronic acids ArB(OH)2 as
carbon-delivering substrates, have shown these reagents to
give good yields of the desired aromatic carbanion products
with LAuBr (where L is a bulky PR3 N-heterocyclic carbene)
and an assisting base. In this report, we describe a transme-
tallation from boron to gold using Ph3PAuCl instead of
LAuBr. The reaction provides an excellent yield of the title
substituted triphenylphosphine gold(I) compound, [(Ph3P)-
AuI(2-C6H4SCH3)], (I), under very controllable conditions.
Efficient protocols for generating Au—C bonded products
are in demand since the optical properties found for such
compounds (Fackler, 2002; Gray, 2007) may be applied in
opto-electronic devices (LEDs, organic LEDs or photovoltaic
cells; Wong & Guo, 2008). Optical properties such as lumi-
Figure 1
The structure of (I), showing the almost linear P—Au—C arrangement.
Displacement ellipsoids are drawn at the 50% probability level.
Acta Cryst. (2009). C65, m299–m301
doi:10.1107/S0108270109017831
# 2009 International Union of Crystallography m299

metal-organic compounds
(0.0386 g, 0.2 mmol) was added. After a few minutes of stirring,
AuPPh3Cl (0.05 g, 0.1 mmol) was added and a condenser was
attached to the reaction flask. The white suspension was refluxed at
333 K for 10 h, after which time the liquid looked clear. Clumps of
white solid slowly formed. The propan-2-ol solution was then reduced
to dryness under vacuum. The dry residue was rinsed with hexane and
extracted with benzene (5 ml). Upon layering the benzene solution
with hexane, shiny crystals of (I) grew within a week, with a yield of
90%. The sample used in data collection was mounted on a loop using
Paratone oil. 1H NMR (CDCl3): ꢂ 7.70–7.45 [m, P(C6H5)3], 7.13–7.07
(m, C6H4), 2.5 (s, S—CH3).
Crystal data
3
˚
[Au(C7H7S)(C18H15P)]
Mr = 582.42
Orthorhombic, P212121
V = 2180 (2) A
Z = 4
Mo Kꢃ radiation
ꢁ = 6.93 mmꢂ1
T = 110 K
0.17 ꢃ 0.10 ꢃ 0.10 mm
˚
a = 6.986 (4) A
˚
b = 15.553 (9) A
˚
c = 20.060 (12) A
Data collection
Bruker APEXII diffractometer
Absorption correction: multi-scan
(SADABS; Sheldrick, 2006)
Tmin = 0.391, Tmax = 0.544
24159 measured reflections
4680 independent reflections
4396 reflections with I > 2ꢄ(I)
Rint = 0.135
Figure 2
Chain formation in (I), mediated by a weak C—Hꢁ ꢁ ꢁꢀ contact. Cg1 is the
(expected range = 0.359–0.500)
centroid of the C1–C6 ring. [Symmetry code: (i) 1 + x, y, z.]
Refinement
R[F2 > 2ꢄ(F2)] = 0.042
wR(F2) = 0.099
S = 1.05
4680 reflections
254 parameters
9 restraints
H-atom parameteꢂrs3 constrained
product is in all likelihood a racemic conglomerate. The chiral
space group P212121 is that which is most frequently observed
for enantiopure crystals, according to Jacques et al. (1981).
Each mononuclear AuI centre has a linear ligand coordi-
nation with geometric parameters inside the remarkably
narrow range found in this family of compounds. There are 17
examples in the Cambridge Structural Database (CSD,
Version 5.30; Allen, 2002) of gold(I) linearly bonded to a
phosphine and to the C atom of an ortho-substituted phenyl
group, including one with an Au—C ꢀ bond; 15 of these report
three-dimensional coordinates (Table 1). Their Au—P and
Au—C distances are similar to those of the title compound
and they also show angular interactions involving phenyl rings
(C—Hꢁ ꢁ ꢁꢀ interactions). 14 are nonchiral and in fact crystal-
lize in centrosymmetric space groups. There is one chiral
compound, the dimer [ꢁ2-1,2-bis(diphenylphosphino)ethane]-
[ꢁ2-2,20-bis(phenylene)methane]digold(I) (Baukanova et al.,
1994), which crystallizes in the space group P21.
˚
Áꢅmax = 2.96 e A
ꢂ3
˚
Áꢅmin = ꢂ1.35 e A
Absolute structure: (Flack, 1983),
with 2016 Friedel pairs
Flack parameter: ꢂ0.003 (11)
Table 1
Main structural features of linear (phosphine)(ortho-substituted phenyl)-
gold(I) compounds.
Compound
Space
group
Au—P
Au—C
P—Au—C
C38H32Au2Pa
P21/a
2.295,
2.297
2.288
2.269,
2.280
2.2643 (10)
2.011,
2.062
2.040
2.052,
2.059
2.299 (5),
176.8,
175.9
179.5
174.8,
174.7
C30H24AuOPb
C48H38Au2OP2
P1
P21/c
b
C27H35AuP+ꢁSbF6
P21/n
157.2,
ꢂc
2.423 (5)†
164.9
C
30H42AuPd
P1
P1
2.291
2.296 (2),
2.295
2.051
2.045 (6),
2.054
174.5
175.5 (2),
177.6
In spite of the presence of four phenyl rings in (I), there are
no ꢀ–ꢀ stacking interactions, but there are angular inter-
actions between C-bound H atoms and the phenyl rings of
neighbouring molecules. There is one C—Hꢁ ꢁ ꢁꢀ contact of
C24H20AuPe
e
C37H32Au2P2
C2/c
P21/c
P1
2.300 (2)
2.279 (8)
2.285
2.07 (2)
2.05 (2)
2.055
175.8 (4)
174.5 (5)
177.1
f
C50H42Au2P2ꢁCH2Cl2
30H24AuPg
C53H77Au2NP2
C
h
C2/c
2.302 (9),
2.302 (13)
2.305 (1)
2.284 (1)
2.296 (5),
2.296 (4)
2.274 (3)
2.289 (5)
2.053 (9),
2.059 (13)
175.82 (19),
177.93 (22)
177.9 (2)
174.8 (2)
179.0 (5),
168.6 (4)
176.5 (5)
170.1 (5)
175.9 (2)
note, from C21—H21 to the centroid Cg1 of the C1–C6 ring of
˚
18H32AuPi
P21/n
P1
P21
2.055 (6)
2.044 (4)
2.04 (2),
2.05 (2)
2.04 (1)
2.040 (2)
2.042 (8)
a
neighbouring molecule, with H21ꢁ ꢁ ꢁCg1i
=
i
2.83 A,
C
C21ꢁ ꢁ ꢁCg1i = 3.584 (9) A and C21—H21ꢁ ꢁ ꢁCg1 = 137ꢀ
[symmetry code: (i) 1 + x, y, z]. The molecules involved in
these contacts form a chain parallel to the a axis (Fig. 2).
i
˚
C44H38Au2P2
39H34Au2P2ꢁ2C6H6
f
C
C13H20AuN3P+ꢁC24H20Bꢂj P21/n
C
12H17AuN3Pj
This work
P21/n
P212121 2.293 (2)
Experimental
† ꢀ side-on gold–phenyl-ring bond. References: (a) Bennett et al. (2004); (b)
Baukanova et al. (1994); (c) Herrero-Gomez et al. (2006); (d) Partyka et al. (2006); (e)
Hong et al. (1994); (f) Baukanova et al. (1997); (g) Osawa et al. (2007); (h) Kui et al.
(2006); (i) Sladek et al. (1995); (j) Forward et al. (1995).
To a suspension of (methylthiophenyl)boronic acid, CH3SC6H4-
B(OH)2 (0.336 g, 0.2 mmol), in propan-2-ol (10 ml), solid CsCO3
ꢄ
m300 Melgarejo et al. [Au(C7H7S)(C18H15P)]
Acta Cryst. (2009). C65, m299–m301

metal-organic compounds
ꢂ3
˚
˚
Bruker–Nonius (2008). APEX2. Version 2008.4-0. Bruker–Nonius Inc.,
Madison, Wisconsin, USA.
Dargel, T. K., Hertwig, R. H. & Koch, W. (1999). Mol. Phys. 96, 583–591.
Fackler, J. P. Jr (2002). Inorg. Chem. 41, 6959–6972.
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The difference peak of 2.96 e A is 0.81 A from the Au1 atom.
Rigid-bond restraints on the displacement parameters of atoms C23,
C24 and C25 (three restraints), and isotropic behaviour restraints at
C24 (six restraints), were applied during refinement. All aromatic H
atoms were placed in calculated positions and refined using a riding
˚
model [C—H = 0.95 A and Uiso(H) = 1.2Ueq(C)]. The H atoms on
Flack, H. D. (1983). Acta Cryst. A39, 876–881.
Forward, J. M., Fackler, J. P. Jr & Staples, R. J. (1995). Organometallics, 14,
4194–4198.
Gray, T. G. (2007). Comments Inorg. Chem. 28, 181–212.
Heng, W. Y., Hu, J. & Yip, J. H. K. (2007). Organometallics, 26, 6760–6768.
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Hong, X., Cheung, K.-K., Guo, C.-X. & Che, C.-M. (1994). J. Chem. Soc.
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methyl atom C7 were located in a local difference Fourier calculation
and refined as riding with a variable torsion angle about the C7—S1
˚
bond [C—H = 0.98 A and Uiso(H) = 1.5Ueq(C7)].
Data collection: APEX2 (Bruker–Nonius, 2008); cell refinement:
APEX2; data reduction: APEX2; program(s) used to solve structure:
SHELXS97 (Sheldrick, 2008); program(s) used to refine structure:
SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED
(Barbour, 2001); software used to prepare material for publication:
SHELXTL (Sheldrick, 2008).
Kui, S. C. F., Huang, J.-S., Sun, R. W.-Y., Zhu, N. & Che, C.-M. (2006). Angew.
Chem. Int. Ed. 45, 4663–4666.
Osawa, M., Hoshino, M. & Hashizume, D. (2007). Chem. Phys. Lett. 436, 89–
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The authors are grateful to the Robert A. Welch Founda-
tion, Houston, Texas, for financial support.
Partyka, D. V., Updegraff, J. B., Zeller, M., Hunter, A. D. & Gray, T. G. (2009).
Organometallics, 28, 1666–1674.
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Supplementary data for this paper are available from the IUCr electronic
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described at the back of the journal.
Rios, D., Olmstead, M. M. & Balch, A. L. (2008). Dalton Trans. pp. 4157–
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ꢄ
Acta Cryst. (2009). C65, m299–m301
Melgarejo et al. [Au(C7H7S)(C18H15P)] m301