Homoleptic gold thiolate catenanes

Full text of DOI:10.1021/ja0011156

12598
J. Am. Chem. Soc. 2000, 122, 12598-12599
Homoleptic Gold Thiolate Catenanes
Matthew R. Wiseman,† Patsy A. Marsh,‡ Peter T. Bishop,‡
Brian J. Brisdon,*,† and Mary F. Mahon†
Department of Chemistry, UniVersity of Bath
Bath BA2 7AY, UK
Johnson Matthey Technology Centre
Sonning Common, Reading RG4 9NH, UK
ReceiVed March 30, 2000
One of the most interesting features in the chemistry of gold
is the subtle effects of weak Au‚‚‚Au interactions on both the
solid-state structural diversity and physical characteristics of Au-
(I) complexes.1 Closed-shell attractions in these compounds are
typically in the range 7-11 kcal/mol for each Au‚‚‚Au bond,2
which is of the same order of magnitude as the strength of a
typical hydrogen bond. As a result both the type and extent of
aggregation in many gold compounds are determined by the subtle
interplay between various types of weak intermolecular interac-
tions.3 We recently showed3b that in the thiolate derivatives [Au-
(PPh3)(SCR2COOH)], association through H-bonding only (R )
Me), and secondary Au‚‚‚S interactions plus H-bonding (R )
H), is preferred over dimerization through Au‚‚‚Au attractions
as found in [Au(PPh3)(SCH3)]4 and other phosphine-containing
thiolate analogues.5 In a search for new examples of gold
compounds in which reinforcement of more than one type of weak
interaction can occur, we have expanded our structural studies to
include homoleptic gold thiolates. This class of molecules was
chosen since the crystal structures of the three homoleptic gold
thiolates which have been determined to date6-8 all exhibit ring
formation involving Au-S interactions only,9 whereas alkanethi-
olate anions are capable of binding two or three [Au(PR3)]+ ions
to afford species which contain Au‚‚‚Au interactions.4
Figure 1. Thermal elipsoid plot (20% probability for clarity) of 1. Ranges
of bond lengths and angles are: Au-S, 2.289(4)-2.343(3); S-C, 1.771-
(8)-1.823(9) Å; Au-S-Au, 99.5(2)-107.26(14); S-Au-S, 172.52-
(12)-178.01(13)°.
Au‚‚‚Au interactions, produce novel examples of inorganic [2]-
catenanes. The only previous known examples10 of gold catenanes
are provided by its acetylide derivatives.
The complexes [{Au(SC6H4-p-CMe3)}10], 1, and [{Au(SC6H4-
o-CMe3)}12], 2, were prepared in over 90% yields by the reaction
of the appropriate tert-butylthiophenol dissolved in xylene with
an aqueous solution of [AuCl(C2H5SC2H4OH)].11 Recrystallization
of 1 from ethoxybenzene and 2 from xylene/acetonitrile yielded
crystals suitable for structure determinations.12,13 Compound 1 has
been synthesized previously by a slightly different procedure,14
but its structure was not determined. The structures of 1 and the
Au10S10 and Au12S12 cores of 1 and 2 are illustrated in Figures
1-3, respectively.
The core of 1 consists of two interpenetrating pentagons defined
by five S atoms and five Au atoms arranged in an alternating
pattern about the periphery, with a sixth Au atom at each pentagon
center. The maximum rms deviations of the central Au atoms
from the least-squares planes containing gold atoms around the
periphery of each pentagon are 0.068 and 0.180 Å, respectively,
and the interplanar angle is 79°. The total of nine close Au‚‚‚Au
contacts (Table 1) which involve Au(1) and Au(6) atoms average
3.05 Å, with much longer Au‚‚‚Au separations (average ) 3.59
Å) occurring around the periphery of each pentagon. All four
Au(1)/Au(6)-S bond lengths are 2.343(3) Å, while the remaining
16 Au-S separations lie within the narrow range 2.289(4)-2.313-
(4) Å. It appears that in 1 the Au-S bond lengths involving the
central atoms are affected by multiple Au‚‚‚Au interactions. The
structure of this unique core can be readily rationalized by
We now report the first two examples in gold chemistry where
Au-S interactions, complemented and reinforced by multi
* Author for correspondence: Telephone: 01225 826517. Fax: 01225
826231. E-mail: B. J.Brisdon@bath.ac.uk.
† University of Bath.
‡ Johnson Matthey Technology Centre.
(1) For recent reviews see: (a) Schmidbaur, H. Chem. Soc. ReV. 1995,
391. (b) Mingos, D. M. P. J. Chem. Soc., Dalton Trans. 1996, 561. (c)
Schmidbaur, H., Ed. Gold. Progress in Chemistry, Biochemistry and Technol-
ogy; Wiley: New York, 1999.
(2) (a) Schmidbaur, H.; Graf, W.; Mu¨ller, G. Angew. Chem., Int. Ed. Engl.
1988, 27, 417. (b) Harwell, D. E.; Mortimer, M. D.; Knobler, C. B.; Anet, F.
A. L.; Hawthorne, M. F. J. Am. Chem. Soc. 1996, 118, 2679. (c) Tang, S. S.;
Chang, C.-P.; Lin, I. J. B.; Liou, L.-S.; Wang, J.-C. Inorg. Chem. 1997, 36,
2294.
(3) (a) Schneider, W.; Bauer, A.; Schmidbaur, H. Organometallics 1996,
15, 5445. (b) Bishop, P.; Marsh, P. A.; Brisdon, A. K.; Brisdon, B. J.; Mahon,
M. F. J. Chem. Soc., Dalton Trans. 1998, 675. (c) Jones, P. G.; Ahrens, B.
New J. Chem. 1998, 10, 1041. (d) Tzeng, B.-C.; Schier, A.; Schmidbaur, H.
Inorg. Chem. 1999, 38, 3978. (e) Ahrens, B.; Jones, P. G.; Fischer, A. K.
Eur. J. Inorg. Chem. 1999, 1103.
(4) (a) Sladek, A.; Angermaier, K.; Schmidbaur, H. J. Chem. Soc., Chem.
Commun. 1996, 1959. (b) Tzeng, B.-C.; Chan, C.-K.; Cheung, K.-K.; Che,
C.-M.; Peng, S.-M. J. Chem. Soc., Chem. Commun. 1997, 135.
(5) (a) Nakamoto, M.; Hiller, W.; Schmidbaur, H. Chem. Ber. 1993, 126,
605. (b) Fackler, J. P., Jr.; Staples, R. J.; Elduque, A.; Grant, T. Acta
Crystallogr., Sect. C 1994, 50, 520.
(9) Gold thiomalate, Na2CsAu2(L)(LH), where L ) [O2CCH2CH(S)CO2]3-
,
although not strictly a homoleptic thiolate contains two interpenetrating -Au-
S- helices in which the closest approach of pairs of Au atoms are 3.485(2)
and 3.227(5) Å. See: Bau, R. J. Am. Chem. Soc. 1998, 120, 9380.
(10) (a) Mingos, D. M. P.; Yau, J.; Menzer, S.; Williams, D. J. Angew.
Chem., Int. Ed. Engl. 1995, 34, 1894. (b) McArdle, C. P. Irwin, M. J.; Jennings,
M. C.; Puddephatt, R. J. Angew. Chem., Int. Ed. 1999, 38, 3376.
(11) Complexes 1 and 2 were prepared in a two-phase reaction between
aqueous [AuCl(EtSC2H4OH)] and the appropriate tert-butylthiophenol dis-
solved in xylene. Procedural details and analytical data are contained in the
Supporting Information.
(12) Crystals of 1‚[0.8(C8 H10 O)] from ethoxybenzene are triclinic (P-1)
with a ) 16.641(3) Å, b ) 17.274(4) Å, c ) 22.703(6) Å, R ) 109.45(2)°,
â ) 93.40(2)°, γ ) 93.41(2)°, V ) 6121.1(24) Å3, Dc ) 2.018 gcm-3, Z )
2. Details are available in the Supporting Information.
(6) Schroter, I.; Stra¨hle, J. Chem. Ber. 1991, 124, 2161.
(7) Bonasia, P. J.; Gindleberger, D. E.; Arnold, J. Inorg. Chem. 1993, 32,
5126.
(8) Wojnowski, W.; Becker, B.; Sassmannhausen, J.; Peters, E. M.; Peters,
K.; Von Schnering, H. G. Z. Anorg. Allg. Chem. 1994, 620, 1417.
(13) Crystals of 2 from xylene are monoclinic (P21/n), a ) 18.108(2) Å,
b ) 26.621(6) Å, c ) 30.256(4) Å, â ) 99.10(3)°, V ) 14401.3(41) Å3, Dc
) 2.117 gcm-3, Z ) 4. Details are available in the Supporting Information.
(14) Al-Sa’ady, A. K. H.; Moss, K.; McAuliffe, C. A.; Parish, R. V. J.
Chem. Soc., Dalton Trans. 1984, 1609.
10.1021/ja0011156 CCC: $19.00 © 2000 American Chemical Society
Published on Web 12/02/2000

Communications to the Editor
J. Am. Chem. Soc., Vol. 122, No. 50, 2000 12599
linear S-Au-S arrangement with Au-S separations in the range
2.287(6)-2.325(5) (average 2.30 Å) persists in both hexagonal
units, but Au‚‚‚Au contacts between the central gold atoms in
each ring, Au(1) and Au(7), and those on the periphery vary
widely (3.19-3.69 Å), and as such are in the same range as Au‚
‚‚Au contacts between gold atoms around the periphery. Buckling
in the second ring permits just two relatively short transannular
Au‚‚‚Au contacts [Au(2)‚‚‚Au(12), 3.16; Au(6)‚‚‚Au(8), 3.21 Å].
All Au‚‚‚Au contacts less than twice the Bondi van der Waals
radius of gold16 are listed in Table 1. It is evident from packing
considerations that the bulky tert-butyl substituent in the ortho
position of the arene ring prevents the formation of a structural
analogue of 1. There are no secondary Au‚‚‚S interactions of
significance in either 1 or 2.
Figure 2. The Au10S10 core of 1 showing the two interpenetrating Au5S5
pentagons and all Au‚‚‚Au interactions less than 3.15 Å.
The weakness of a single aurophilic interaction generally results
in its complete disruption on dissolution, but occasionally an
equilibrium is observed between associated and dissociated
species.17 The room-temperature proton NMR spectrum of 1 in
noncoordinating organic solvents contains three sets of methyl
and aromatic resonances in the ratio 1:2:2. This is in keeping
with the inequivalence of the ligands on the periphery of
interlinked pentagons as in the core of the solid. At low
temperatures line broadening is followed by band splitting at -90
°C as ligand motion is restricted. We have confirmed previous
findings14 that at elevated temperatures single sets of methyl and
aromatic resonances are observed, but we have been unable to
determine whether the core remains intact under these conditions.
Preliminary mass spectral studies using low resolution FAB
revealed a complex fragmentation pattern in which [AuxSy(SC6H4-
p-CMe3)z)]+ species, x ) 5 or 6, y ) 0-2, z ) 5 predominate,
but which also includes higher cluster species including [Au11S2-
(SC6H4-p-CMe3)9]+. The proton NMR spectrum of 2 is far more
complex than that of 1, and it is both temperature- and solvent-
dependent, with evidence of more than one species being present
in solution at ambient temperatures.
Complete dissociation of both 1 and 2 is readily effected by
chemical reactions involving soft donors. Thus, in the presence
of triphenylphosphine 1 forms [Au(PPh3)SC6H4-p-CMe3], 3, in
almost quantitative yield. According to X-ray crystallography18
the individual molecules have the normal quasi-linear coordination
at gold with a Au-S-C bond angle of 106.6(2)°. There are no
short intermolecular Au‚‚‚Au or Au‚‚‚S contacts present.
In summary, the electronic and structural preferences evident
in many coordination complexes of Au(I) are perfectly combined
in the [2]catenane structure found for the Au10S10 core of 1. Unlike
[2]catenanes which have been the subject of much recent interest19
and are either entirely or largely organic based, there is a unique
“spoke” system in both rings of 1 consisting of a total of nine
Au‚‚‚Au interactions which imparts structural stability.
Figure 3. The Au12S12 core of 2 showing only eight alpha C atoms of
the phenyl rings for clarity. Ranges of bond lengths and angles are: Au-
S, 2.287(6)-2.435(5); S-C, 1.779(13)-1.819(12) Å; Au-S-Au, 88.0-
(2)-108.1(2); S-Au-S, 162.8(2)-178.2(2)°.
Table 1. Au‚‚‚Au Separations in 1 and 2 less than 3.32 Å
compound 1
Au-Au
compound 2
Au-Au
/Å
/Å
1-2
1-3
1-4
1-5
6-1
6-7
6-8
6-9
6-10
2.97
3.03
3.12
2.98
3.05
3.10
3.12
3.05
3.05
1-3
1-4
1-5
1-6
2-3
2-12
4-5
5-6
6-8
7-8
7-12
10-11
3.25
3.20
3.27
3.19
3.30
3.16
3.28
3.21
3.21
3.22
3.21
3.19
consideration of the structural parameters found in many other
thiolates.15 The normal linear coordination about Au atoms
combined with Au-S separations of 2.30 Å and an angular Au-
S-Au arrangement averaging 105° defines a planar pentagon of
side 4.6 Å. These geometric constraints maximize the number of
stabilizing Au‚‚‚Au contacts possible for an in-plane Au located
at the center of the ring and impose a value of 3.0 Å for each
Au‚‚‚Au “spoke” in the pentagonal cartwheel.
Acknowledgment. We thank the Engineering and Physical Sciences
Research Council (EPSRC) for support. We also wish to acknowledge
the use of the EPSRC’s National Mass Spectrometry and Chemical
Database Services at Swansea and Daresbury, UK, respectively.
Supporting Information Available: Synthetic and analytical data
on compounds 1 and 2. Tables of crystallographic data including
diffractometer data and refinement data, final coordinates, bond lengths,
bond angles, and anisotropic displacement parameters for molecular
species 1 and 2 (PDF). This material is available free of charge via the
Internet at http://pubs.acs.org.
JA0011156
(16) Bondi, A. J. Phys. Chem. 1964, 68, 441
The central core of 2 can also be described as a [2]catenane,
but neither of the two interpenetrating hexagons, each defined
by a total of 12 alternating S and Au atoms, is planar. The near
(17) Narayanaswarmy, R.; Young, M. A.; Parkhurst, E.; Oullette, M.; Kerr,
M. E.; Ho, D. M.; Elder, R. C.; Bruce, A. E.; Bruce, M. R. M. Inorg. Chem.
1993, 32, 2506.
(18) Crystals of 3 from xylene/acetonitrile are triclinic (P-1), a ) 8.353-
(2) Å, b ) 11.969(3) Å, c ) 13.582(4) Å, R ) 109.82(2)°, â ) 103.50(2)°,
γ ) 93.43(2)°, V ) 1227.7(6) Å3, Dc ) 1.689 gcm-3, Z ) 2. Full details of
the structure will be published elsewhere.
(19) Stoddart, J. F.; Raymo, F. M. Chem. ReV. 1999, 99, 1643.; Fujita, M.
Acc. Chem. Res. 1999, 32, 53.; Fujita, M.; Ogura, K. Coord. Chem. ReV. 1996,
148, 249.
(15) A survey of entries in EPSRC’s Chemical Database revealed an
average Au-S-Au bond angle of 91° for Au(I)-thiolate derivatives contain-
ing the Au-S-Au linkage and 95° (range 105.4-82.9°) for the same angle
in homoleptic Au(I)-thiolates. See The United Kingdom Chemical Database
Service, Fletcher, D. A.; McMeeking, R. F.; Parkin, D. Chem. Inf. Comput.
Sci. 1996, 36, 746