Terminally bifurcated tetraaurio-α,ω-bis(sulfonium) salts as building blocks for auriophilicity-determined coordination polymers

Article abstract of DOI:10.1021/ic9516119

Treatment of α,ω-dithiols HS(CH₂)_nSH, n = 4 or 5, with tris[(triphenylphosphine)aurio]oxonium tetrafluoroborate affords the corresponding S,S,S′,S′-tetrakis[(triphenylphosphine)aurio]-α,ω- alkanediylbis(sulfonium) bis(tetrafluoroborates) of the type {[(Ph₃P)Au]₂S(CH₂)_nS[Au(PPh ₃)]₂}²⁺2BF₄^-. The crystal structure of the species with n = 5 has been determined by single crystal X-ray diffraction studies. In the lattice the unfolded dications are linked into chains through short double Au-Au contacts between the terminal bifurcated diauriosulfonium centers. The analogous reactions with (racemic) 1,2-dithioglycerol and 1,2,3-trithioglycerol also give tri- and tetranuclear complexes with a varying distribution of the metal atoms over the chalcogen(ium) centers. As again demonstrated in a single crystal X-ray diffraction study, the dications {HOCH₂HCS[(Ph₃P)Au]₂CH₂S[Au(PPh ₃)]₂}²⁺ of the dithioglycerol compound form only dimers through auriophilicity-determined pairing of the bifurcated ends, while the open ends are shielded by the dangling hydroxyl group. The trinuclear complex of 1,2-dithioglycerol is fluxional in solution; the crystal structure has not been determined but is expected to be similar to that derived for the analogous dithioglycol complex. The tetranuclear, trithioglycerol-based dications of {[(Ph₃P)-Au]SCH₂CHS[Au(PPh₃)]CH ₂S[Au(PPh₃)]₂}⁺BF₄ ^- are isolated in the lattice and feature an unsymmetrical complexation, which is an extension of the structure of the trinuclear dithioglycol analogue {(CH₂S)₂[Au{PPh₃)]₃}⁺ with its strong intramolecular Au-Au contacts. A similar structure is proposed for the monocation {CH₂(CH₂S)_2- [Au(PPh₃)]₃}⁺ obtained from propane- 1,3-dithiol. The structures of these cations are also fluxional in solution, however, as shown by variable-temperature NMR studies.

Full text of DOI:10.1021/ic9516119

3268
Inorg. Chem. 1996, 35, 3268-3272
Terminally Bifurcated Tetraaurio-r,ω-bis(sulfonium) Salts as Building Blocks for
Auriophilicity-Determined Coordination Polymers
Alexander Sladek and Hubert Schmidbaur*
Anorganisch-chemisches Institut der Technischen Universita¨t Mu¨nchen, Lichtenbergstrasse 4,
D-85747 Garching, Germany
ReceiVed December 15, 1995X
Treatment of R,ω-dithiols HS(CH2)nSH, n ) 4 or 5, with tris[(triphenylphosphine)aurio]oxonium tetrafluoroborate
affords the corresponding S,S,S′,S′-tetrakis[(triphenylphosphine)aurio]-R,ω-alkanediylbis(sulfonium) bis(tetrafluo-
roborates) of the type {[(Ph3P)Au]2S(CH2)nS[Au(PPh3)]2}2+2BF4-. The crystal structure of the species with n )
5 has been determined by single crystal X-ray diffraction studies. In the lattice the unfolded dications are linked
into chains through short double Au-Au contacts between the terminal bifurcated diauriosulfonium centers. The
analogous reactions with (racemic) 1,2-dithioglycerol and 1,2,3-trithioglycerol also give tri- and tetranuclear
complexes with a varying distribution of the metal atoms over the chalcogen(ium) centers. As again demonstrated
in a single crystal X-ray diffraction study, the dications {HOCH2HCS[(Ph3P)Au]2CH2S[Au(PPh3)]2}2+ of the
dithioglycerol compound form only dimers through auriophilicity-determined pairing of the bifurcated ends, while
the open ends are shielded by the dangling hydroxyl group. The trinuclear complex of 1,2-dithioglycerol is
fluxional in solution; the crystal structure has not been determined but is expected to be similar to that derived
for the analogous dithioglycol complex. The tetranuclear, trithioglycerol-based dications of {[(Ph3P)-
-
Au]SCH2CHS[Au(PPh3)]CH2S[Au(PPh3)]2}+BF4 are isolated in the lattice and feature an unsymmetrical
complexation, which is an extension of the structure of the trinuclear dithioglycol analogue {(CH2S)2[Au(PPh3)]3}+
with its strong intramolecular Au-Au contacts. A similar structure is proposed for the monocation {CH2(CH2S)2-
[Au(PPh3)]3}+ obtained from propane-1,3-dithiol. The structures of these cations are also fluxional in solution,
however, as shown by variable-temperature NMR studies.
Introduction
Scheme 1
Hydrogen sulfide and thiols are known to form tetra-, tri-,
and dinuclear auriosulfonium complexes with interesting su-
pramolecular structures.1-6 The individual cations {S[Au-
(PR3)]3}+ and {RS[Au(PR3)]2}+ are associated into dimers or
even polymers through short intermolecular Au-Au contacts
(auriophilicity,7 Scheme 1). These gold-rich sulfonium salts
are thermally quite stable, not sensitive to air and moisture under
X Abstract published in AdVance ACS Abstracts, May 1, 1996.
(1) (a) Schro¨tter, I.; Stra¨hle, J. Chem. Ber. 1991, 124, 2161. (b) Wojnowski,
W.; Becker, B.; Sassmannshausen, J.; Peters, E.-M.; Peters, K.; v.
Schnering, H. G. Z. Anorg. Allg. Chem. 1994, 620, 1417. (c) Brust,
M.; Bethell, D.; Schiffrin, D. J.; Kiely, C. J. AdV. Mater. 1995, 7,
795.
(2) (a) Kowala, C.; Swan, J. M. Aust. J. Chem. 1966, 19, 547. (b)
Schmidbaur, H.; Franke, R.; Eberlein, J. Chem. Ztg. 1975, 99, 91. (c)
Lensch, C.; Jones, P. G.; Sheldrick, G. M. Z. Naturforsch. 1982, 37b,
944. (d) Hofreiter, S.; Paul, M.; Schmidbaur, H. Chem. Ber. 1995,
128, 901.
(3) (a) Abel, E. W.; Jenkins, C. R. J. Organomet. Chem. 1968, 14, 285.
(b) Jones, P. G.; Sheldrick, G. M.; Ha¨dicke, E. Acta Crystallogr. 1980,
B36, 2777. (c) Schmidbaur, H.; Kolb, A.; Zeller, E.; Schier, A.; Beruda,
H. Z. Anorg. Allg. Chem. 1993 , 619, 1575. (d) Angermaier, K.;
Schmidbaur, H. Chem. Ber. 1994, 127, 2387.
(4) Canales, F.; Gimeno, M. C.; Jones, P. J.; Laguna, A. Angew. Chem.
1994, 106, 811; Angew. Chem., Int. Ed. Engl. 1994, 33, 769.
(5) (a) Nakamoto, M.; Hiller, W.; Schmidbaur, H. Chem. Ber. 1993, 126,
605. (b) Fackler Jun, J. P.; Staples, R. J.; Elduque, A.; Grant, T. Acta
Crystallogr. 1994, C50, 520. (c) Jones, W. B.; Yuan, J.; Naraya-
naswamy, R.; Young, M. A.; Elder, R. C.; Bruce, A. E.; Bruce, M. R.
M. Inorg. Chem. 1995, 34, 1996 and references therein.
(6) (a) Wang, S.; Fackler Jun, J. P. Inorg. Chem. 1990, 29, 4404. (b)
KuzÅmina, L. G.; Dvortsova, N. V.; Smyslova, E. I.; Grandberg, K. I.
Russ. J. Inorg. Chem. 1992, 37, 1420.
standard conditions, and highly soluble in polar organic solvents.
These properties qualify the compounds as substrates for
electrochemical or electroless deposition of gold from solutions,
for the reductive preparation of gold colloids (cluster solutions),
and as gold drugs for chemotherapy,8 where their role as
component of equilibria has already been firmly established.8h
(8) (a) Hunt, L. B. Gold Bull. 1979, 12, 116. (b) Parish, R. V. Interdisc.
Sci. ReV. 1992, 17, 221. (c) Sadler, P. J. J. AdV. Inorg. Chem. 1991,
36, 1. (d) Rapson, W. S.; Groenewald, T. Gold Usage; Academic
Press: London, 1978. (e) Brown, D. H.; Smith, W. E. Chem. Soc.
ReV. 1980, 9, 217. (f) Dash, K. C.; Schmidbaur, H. In Metal Ions in
Biological Systems; Sigel, H., Ed.; Marcel Dekker: New York, 1982;
Vol. 14, p 179. (g) Sutton, B. M. Gold Bull. 1986, 19, 15. (h) Hempel,
J.; Mikuriya, Y.; Shaw, C. F., III In Bioinorganic Chemistry of Gold
Coordination Compounds, Proceedings of a Symposium; Sutton, B.
M., Ed.; Smith Kline & French Laboratories: Philadelphia, 1983; pp
37, 97.
(7) (a) Pyykko¨, P.; Zhao, Y.-F. Angew. Chem., Int. Ed. Engl. 1991, 30,
604; Angew. Chem. 1991, 103, 622. (b) Schmidbaur, H. Interdiscip.
Sci. ReV. 1992, 17, 213. (c) Li, J.; Pyykko¨, P. Chem. Phys. Lett. 1992,
197, 586. (d) Schmidbaur, H. Pure Appl. Chem. 1993, 65, 691. (e)
Li, J.; Pyykko¨, P. Inorg. Chem. 1993, 32, 2630.
S0020-1669(95)01611-9 CCC: $12.00 © 1996 American Chemical Society

Tetraaurio-R,ω-bis(sulfonium) Salts
Inorganic Chemistry, Vol. 35, No. 11, 1996 3269
129.45 [d, J ) 11.0, Cmeta], 131.9 [d, J ) 2.8, Cpara], 1323.7 [d, J )
13.8, Cortho]. 1H NMR (CDCl3, 25 °C): 1.85 [m, 4H, H2C], 3.0 [m,
4H, CH2C], 7.30-7.50 [m, 60H, HPh]. Anal. Calcd (Found) for C76H68-
Au4B2F8P4S2 (Mr ) 2130.88): C, 42.84 (43.01); H, 3.22 (3.20); Au,
36.97 (37.51).
Most of the previous studies have been limited to derivatives
of H2S [or (Me3Si)2S] and of monofunctional thiols RSH, except
for some recent investigations which also included dithiocat-
echol, dithioglycol, and dithioglycerol (BAL).8h,9 We have
therefore initiated a more systematic study of polynuclear gold-
(I) complexes of R,ω-alkanediyldithiols HS(CH2)nSH with n
) 3, 4, and 5 and of di- and trithioglycerols. It was anticipated
that the corresponding terminally bifurcated disulfonium salts
would show interesting aggregation to give either strong
intramolecular Au-Au interactions or supramolecular structures
based on intermolecular Au-Au contacts between the geminal
SAu2 units.
(n-Pentane-1,5-dithiolato)tetrakis[(triphenylphosphine)gold(I)] Bis-
(tetrafluoroborate) (3). A solution of the oxonium salt (above, 0.29
g, 0.20 mmol) and NaBF4 (0.1 g, 0.91 mmol) in CH2Cl2 (10 mL) is
treated with 1,5-pentanedithiol (0.02 mL, 0.15 mmol) at room tem-
perature with stirring. After 1 h a brown precipitate is removed by
filtration and the filtrate layered with diethyl ether (30 mL) at -78 °C.
After 12 h colorless crystals are isolated (0.15 g, 45% yield), mp 179
°C (dec). MS (FD, CH2Cl2): m/z ) 985.9 [M2+/2, 100%]. {1H} 31P
NMR (CDCl3, 25 °C): δ ) 37.3 [s]. {1H} 13C NMR (CDCl3, 25 °C):
δ ) 27.2 [s, CH2CCS], 32.3 [s, CH2CS], 36.0 [s,CH2S], 127.5 [d, JP,C
) 60.7 Hz, Cipso], 129.8 [d, J ) 11.0, Cmeta], 132.6 [s, Cp], 133.9 [d, J
) 12.9, Cortho]. 1H NMR (CDCl3, 25 °C): 1.66 [m, 2H, CH2CCS],
1.87 [m, 4H, CH2CS], 3.37 [m, 4H, CH2S], 7.41-7.51 [m, 60H, HPh].
Anal. Calcd (Found) for C77H70Au4B2F8P4S2 (Mr ) 2144.91): C, 43.12
(42.78); H, 3.29 (3.28); Au, 36.73 (37.10).
(3-Hydroxypropane-1,2-dithiolato)tetrakis[(triphenylphosphine)-
gold(I)] Bis(tetrafluoroborate) (4). A solution of the oxonium salt
(above, 0.49 g, 0.33 mmol) and NaBF4 (0.10 g, 0.91 mmol) in
dichloromethane (10 mL) is treated with racemic 2,3-dithioglycerol
(0.025 g, 0.25 mmol) at ambient temperature with stirring. After 75
min the reaction mixture is filtered and the solvent is removed from
the filtrate. The residue is treated with ethanol and filtered, the filtrate
again brought to dryness in a vacuum, and the filtrate redissolved in
dichloromethane. This solution is layered with diethyl ether to
crystallize the product as colorless needles (0.12 g, 23% yield), mp
165 °C (dec). MS (FAB): m/z ) 1498.9 [{M-AuPPh3}+, 15%], 979.0
[M2+, 1.3%], 720.9 [{(Ph3P)2Au}+, 100%]. {1H} 31P NMR (CDCl3,
25 °C): δ ) 34.6 [s]; -30 °C, 34.0 [s], -60 °C: 33.6 [s]. {1H} 13C
NMR (CDCl3, 25 °C): δ ) 37.4 [s, CH2S], 56.7 [s, CH], 67.7 [s, CH2-
OH], 127.6 [d, JP,C ) 59.8 Hz, Cipso], 129.7 [d, J ) 11.9, Cmeta], 130.1
[s, Cpara], 133.8 [d, J ) 13.8, Cortho]. 1H NMR (CDCl3, 25 °C): δ )
1.77 [s, 1H, OH], 3.79-3.95 [m, 5H, CH2/CH], 7.20-7.71 [m, 60H,
HPh]. Anal. Calcd (Found) for C75H66Au4B2F8OP4S2 (Mr ) 2132.86):
C, 42.24 (41.84); H, 3.12 (3.14); Au, 36.94 (37.44).
Regarding the preparation of the poly(aurio)sulfonium salts,
the established literature method using tris[(phosphine)aurio]-
-
oxonium salts [(R3P)Au]3O+BF4 appeared to be the most
convenient technique for the auration of thiols. (Phosphine)-
-
gold tetrafluoroborates [(R3P)Au]+BF4 are more powerful
aurating agents, which can even lead to hypercoordination of
sulfur.4 This was not within the scope of the present study,
however, because the excessively aurated products are expected
to be of a more limited stability and hence less suitable as
sources for gold in or from solution under standard conditions.
Experimental Section
General Information. The experiments were carried out routinely
under an atmosphere of dry and pure nitrogen. Glassware and solvents
were dried and filled/saturated with nitrogen. NMR: Jeol GX 400
spectrometer; deuterated solvents with the usual standards. MS: Varian
MAT 311A instrument (FAB, p-nitrobenzyl alcohol, or FD, dichlo-
romethane solvent). The thiols were commercially available, except
-
for trithioglycerol.10 [(Ph3P)Au]3O+BF4 was prepared following the
literature procedure.11
(Propane-1,3-dithiolato)tris[(triphenylphosphine)gold(I)] Tet-
-
rafluoroborate (1). A solution of [(Ph3P)Au]3O+BF4 (0.30 g, 0.20
mmol) in dichloromethane (10 mL) is treated with 1,3-propanedithiol
(0.02 mL, 0.20 mmol) at ambient temperature with stirring. After 1 h
a gray-white flaky precipitate is filtered off and the solvent is evaporated
from the filtrate in a vacuum to leave a white powder (0.24 g, 75%
yield). The product could not be crystallized. MS: m/z ) 1483.3 [M+,
17%], 721 [{(Ph3P)2Au}+, 100%]. {1H} 31P NMR (CDCl3, 25 °C): δ
) 38.2 [s]. {1H} 13C NMR (CDCl3, 25 °C): δ ) 29.3 [s, CH2S], 46.0
[s, CH2C], 129.0 [d, JP,C ) 54.2 Hz, Cipso], 129.4 [d, J ) 11.0, Cmeta],
132.0 [d, J ) 2.8, Cpara], 133.8 [d, J ) 13.8, Cortho]. 1H NMR (CDCl3,
25 °C): 2.13 [m, 2H, CH2C], 3.14 [m, 4H, CH2S], 7.31-7.50 [m, 45
(3-Hydroxypropane-1,2-dithiolato)tris[(triphenylphosphine)gold-
(I)] Tetrafluoroborate (5). A solution of the oxonium salt (above,
0.44 g, 0.33 mmol) in CH2Cl2 (10 mL) is treated with racemic 2,3-
dithioglycerol (0.03 mL, 0.33 mmol) at ambient temperature with
stirring. After 60 min the reaction mixture is layered with diethyl ether
(40 mL). A precipitate is formed, which is filtered off after 12 h and
taken up in ethanol. The solution is filtered and the filtrate brought to
dryness in a vacuum to leave a white solid (0.20 g, 43% yield). The
product could not be crystallized. MS (FAB): m/z ) 1498.2 [M+,
20%], 1408.3 [{S(AuPPh3)3}+, 100%]. {1H} 31P NMR (CDCl3, 25
°C): δ ) 35.7 [s]; -55 °C, 34.7 [s]. {1H}13C NMR (CDCl3, 25 °C):
H, HPh]. Anal. Calcd (Found) for C57H51Au3BF4P3S2 (Mr
1570.80): C, 43.58 (43.77); H, 3.27 (3.28); Au, 37.62 (37.00).
)
(n-Butane-1,4-dithiolato)tetrakis[(triphenylphosphine)gold(I)] Bis-
(tetrafluoroborate) (2). A solution of the oxonium salt (above, 0.50
g, 0.34 mmol) in CH2Cl2 (10 mL) is treated with NaBF4 (0.10 g, 0.91
mmol) and then with 1,4-butanedithiol (0.03 mL, 0.26 mmol) at ambient
temperature with stirring. After 30 min a white flaky precipitate is
removed by filtration and the filtrate layered at -20 °C with diethyl
ether (20 mL). After 15 h clear colorless crystals are obtained (0.27
g, 49% yield), mp 165 °C (dec). MS (FD, CH2Cl2): m/z ) 1955.3
[(M - 1)+, 3.4%], 1408.2 [{(Ph3P)Au}3S+, 100%]. MS (FAB): m/z
) 2043.4 [{M + BF4}+, 10.5%], 720.4 [{(Ph3P)2Au}+, 100%]. {1H}
31P NMR (CDCl3, 25 °C): δ ) 39.5 [s]. {1H} 13C NMR (CDCl3, 25
°C): 30.6 [s, CH2S], 35.9 [s, CH2C], 129.4 [d, JP,C ) 51.5 Hz, Cipso],
δ ) 40.1 [s, CH2S], 57.0 [s, CH], 68.1 [s, CH2O], 128.8 [d, JP,C
)
57.3 Hz, Cipso], 129.3 [d, J ) 11.9, Cmeta], 131.9 [s, Cpara], 133.8 [d, J
) 13.7, Cortho]. 1H NMR (CDCl3, 25 °C): δ ) 1.85 [s, 1H, OH], 3.90-
4.10 [m, 5H, CH2/CH], 7.15-7.57 [m, 45H, HPh]. Anal. Calcd (Found)
for C57H51Au3BF4OP3S2 (Mr ) 1586.79): C, 43.15 (43.54); H, 3.24
(3.25); Au, 37.24 (38.40).
(Propane-1,2,3-trithiolato)tetrakis[(triphenylphosphine)gold(I)]
Tetrafluoroborate (6). A solution of the oxonium salt (above, 0.52
g, 0.35 mmol) in CH2Cl2 (10 mL) is treated with trithioglycerol (0.030
mL, 0.26 mmol) at room temperature with stirring. After 1 h the
reaction mixture is layered with diethyl ether (20 mL) at -78 °C. A
brown oil and yellow crystals are formed (12 h). The crystals are
separated by decantation (0.35 g, 65% yield), mp 198 °C (dec). MS
(FAB): m/z ) 1973.5 [{M - 1}+, 4.3%], 458.8 [{Ph3PAu}+, 100%].
{1H} 31P NMR (CDCl3, 25 °C): δ ) 35.6 [s]. {1H} 13C NMR (CDCl3,
25 °C): δ ) 37.1 [s, CH2], 59.6 [s, CH], 129.1 [d, JP,C ) 11.0 Hz,
Cmeta], 129.7 [s, J ) 55.2, Cipso], 132.6 [s, Cpara], 133.8 [d, J ) 13.8,
Cortho]. 1H NMR (CDCl3, 25 °C): δ ) 3.66 [m, 4H, CH2], 3.74 [m,
1H, CH], 7.17-7.38 [m, 60H, HPh]. Anal. Calcd (Found) for C75H65-
Au4BF4P4S3 (Mr ) 2061.11): C, 43.71 (44.07); H, 3.18 (3.19); Au,
38.23 (37.72).
(9) (a) Nakamoto, M.; Koijman, H.; Paul, M.; Hiller, W.; Schmidbaur,
H. Z. Anorg. Allg. Chem. 1993, 619, 1341. (b) Davila, R. M.; Elduque,
A.; Grant, T.; Staples, R. J.; Fackler Jun, J. P. Inorg. Chem. 1993, 32,
1749. (c) Nakamoto, M.; Schier, A.; Schmidbaur, H. J. Chem. Soc.,
Dalton Trans. 1993, 1347. (d) Concepcio´n Gimeno, M.; Jones, P. G.;
Laguna, A.; Terroba, R. Inorg. Chem. 1994, 33, 3932. (e) Sladek, A.;
Schmidbaur, H. Chem. Ber. 1995, 128, 907. (f) Yip, H. K.; Schier,
A.; Riede, J.; Schmidbaur, H. J. Chem. Soc., Dalton Trans. 1994, 2333.
(10) Wragg, R. T. J. Chem. Soc (C) 1969, 2087.
(11) Nesmeyanov, A. N.; Perevalova, E. G.; Struchkov, Y. T.; Antipin,
M. Y.; Grandberg, K. I.; Dyadchenko, V. P. J. Organomet. Chem.
1980, 201, 343.
Crystal Structure Determinations. Suitable crystals of compounds
3, 4, and 6 were sealed under argon at dry ice temperature into glass

3270 Inorganic Chemistry, Vol. 35, No. 11, 1996
Sladek and Schmidbaur
Table 1. Crystallographic Data for Compounds 3, 4‚CH2Cl2, and 6‚CH2Cl2‚(CH3CH2)2O
3
4‚CH2Cl2
6‚CH2Cl2‚(CH3CH2)2O
empirical formula
formula weight
crystal system
space group (No.)
a [Å]
b [Å]
c [Å]
C77H70Au4B2F8P4S2
2144.81
triclinic
C75H66Au4B2F8OP4S2‚CH2Cl2
2217.69
triclinic
C75H65Au4BF4P4S3‚CH2Cl2‚(CH3CH2)2O
2220.05
triclinic
P1h (2)
P1h (2)
P1h (2)
12.869(2)
14.365(2)
22.559(3)
78.99(1)
89.24(1)
64.81(1)
3693.40
1.942
13.420(1)
14.558(2)
20.857(3)
108.55(1)
94.78(1)
96.14(1)
3811.05
1.933
10.934(1)
18.502(2)
20.393(3)
77.40(1)
79.07(2)
83.75(1)
3943.31
1.870
R [deg]
â [deg]
γ [deg]
V [Å3]
F
calc [g cm-3
]
Z
2
2
2
µ(Mo KR) [cm-1
T [°C]
]
81.80
79.50
77.00
-68
-68
-62
radiation
scan
hkl range
measured reflections
unique reflections
observed reflections
Fo g
Mo KR
Mo KR
Mo KR
ω
θ-θ
θ-θ
(15/(17/+26
(16/(17/+25
(13/+22/(25
12 848
14 856
14 656
11 082
8581
4σ(Fo)
651
0.0560
0.0704
+1.83/-2.35
empirical
0.2050/0.9998
l ) 1.0000/k ) 0.001147
12 810
9902
4σ(Fo)
679
0.0539
0.0583
+2.16/-2.03
empirical
0.5399/0.9994
unit weights
13 104
10 781
4σ(Fo)
713
0.0400
0.0418
+1.70/-1.30
empirical
0.5226/0.9994
l ) 1.0000/k ) 0.000238
refined parameters
Ra
Rw
b
Ffin(max/min) [e Å-3
]
abs corr
T
min/Tmax
weighting schemec
2
2
a R ) ∑||Fo| - Fc||/∑|Fo|. b Rw ) [∑w(|Fo| - Fc|)2/∑wFo ]1/2
.
c w ) l/σ2(Fo) + kFo .
capillaries and examined directly on the diffractometer. Data were
corrected for Lorentz, polarization, and absorption effects. Structures
were solved by direct methods and refined by full-matrix least-squares
calculations. The thermal motion was treated anisotropically for all
non-hydrogen atoms, except for seven phenyl carbon atoms of
compound 3 and except for the disordered CH2OH group of compound
4. All calculated hydrogen atoms were treated isotropically. More
detailed information on solution and refinement procedures is given in
the Supporting Information, as are the atomic coordinates.
homologue (3, below).
HS(CH2)4SH + [(Ph3P)Au]3O+BF4- f
H2O + {[(Ph3P)Au]2[S(CH2)4S][Au(PPh3)]2}2+(BF4 )2 (2)
-
(2)
Pentane-1,5-dithiol gave the analogous tetranuclear derivative
(3) in moderate yield (eq 2), which showed physical and
spectroscopic properties very similar to those of compound 2.
Single crystals were readily obtained, which were shown to be
triclinic, space group P1h (No. 2, Int. Tables) with two formula
units in the unit cell (Table 1). The lattice is composed of
isolated independent tetrafluoroborate anions and chains of
cations. In the individual units of these chains the five-
membered hydrocarbon moiety is unfolded, with a bifurcated
S(AuL)2 function at either end (L ) PPh3, Figure 1).
The diauriosulfonium groups are in close contact with the
corresponding units of neighboring molecules in an inverse
orientation to form only slightly distorted squares of gold atoms
around crystallographic centers of inversion (Figure 2). This
auriophilicity-based pairing of bifurcated units is known from
the structural chemistry of diaurated monosulfonium salts but
is observed here for the first time for R,ω-difunctional substrates.
Owing to the double fixation (two Au-Au contacts at either
end), the supramolecular structures of 2 and 3 are probably quite
robust, with estimated enthalpies of aggregation of at least 15
kcal per pair of connecting units.12 Note that this aggregation
occurs between cationic units (and thus against repulsive
Coulomb forces) and that the gold atoms become nearest
neighbors, and not gold and sulfur. These are common criteria
for auriophilicity phenomena.
Results and Discussion
The reaction of propane-1,3-dithiol with equivalent amounts
of tris[(triphenylphosphine)aurio]oxonium tetrafluoroborate in
dichloromethane at room temperature leads, in high yield, to a
colorless microcrystalline precipitate, which was shown to be
the trinuclear complex 1 formulated in eq 1. The product was
identified by elemental analysis, fast atom bombardment mass
spectrometry, and NMR spectroscopy (Experimental Section).
On the basis of these data, a structure is proposed for 1, which
resembles that of the analogous products obtained from dithioglyc-
erol and dithiocatechol. No single crystals suitable for diffrac-
tion studies could be obtained.
HS(CH2)3SH + [(Ph3P)Au]3O+BF4- f
H2O + {[S(CH2)3S][Au(PPh3)]3}+BF4- (1) (1)
Under similar reaction conditions, butane-1,4-dithiol was con-
verted into a tetranuclear complex 2, which was obtained in
moderate yield as colorless crystals upon layering of the
dichloromethane solutions with diethyl ether at -78 °C (eq 2).
The composition was confirmed by standard analytical tech-
niques, but none of the single crystals had the quality necessary
for a structure determination. The structure proposed tentatively
for this product is based on the findings for the pentane
(12) (a) Dziwok, K.; Lachmann, J.; Wilkinson, D. L.; Mu¨ller, G. Chem.
Ber. 1990, 123, 423. (b) Schmidbaur, H.; Dziwok, K.; Grohmann,
A.; Mu¨ller, G. Chem. Ber. 1989, 122, 893. (c) Schmidbaur, H.; Graf,
W.; Mu¨ller, G. Angew.Chem. 1988, 100, 439; Angew. Chem., Int. Ed.
Engl. 1988, 27, 416.

Tetraaurio-R,ω-bis(sulfonium) Salts
Inorganic Chemistry, Vol. 35, No. 11, 1996 3271
Figure 1. Structure of the dication in the crystal of {[(Ph3P)Au]2-
S(CH2)5S[Au(PPh3)]2}2+(BF4-)2 3 (ORTEP, except for phenyl carbon
atoms; hydrogen atoms omitted for clarity). Selected distances [Å] and
angles [deg]: Au1-Au2, 3.224(1); Au1-S1, 2.330(3); Au1-P1, 2.267-
(3); Au2-S1, 2.314(5); Au2-P2, 2.259(5); Au3-Au4, 3.071(1); Au3-
S2, 2.331(3); Au3-P3, 2.261(4); Au4-S2, 2.328(5); Au4-P4, 2.252-
(7); Au1-S1-Au2, 87.9(1); Au1-S1-C1, 109.9(5); Au2-S1-C1,
105.4(7); P1-Au1-S1, 176.0(2); P2-Au2-S1, 177.0(1); Au3-S2-
Au4, 82.5(1); Au3-S2-C5, 107.4(5); Au4-S2-C5, 106.2(8); P3-
Au3-S2, 179.1(2); P4-Au4-S2, 178.0(2).
Figure 3. A pair of dications {HOCH2HCS[(Ph3P)Au]2CH2S[Au-
(PPh3)]2}2+ in the tetrafluoroborate salt 4 (ORTEP, except for phenyl
carbon atoms and the CH2OH group; hydrogen atoms omitted for
clarity). Selected distances [Å] and angles [deg]: Au1-Au2, 3.101-
(1); Au1-S1, 2.357(3); Au1-P1, 2.275(4); Au2-S1, 2.331(4); Au2-
P2, 2.261(5); Au3-Au4, 3.040(1); Au3-S2, 2.331(4); Au3-P3,
2.254(4); Au4-S2, 2.316(4); Au4-P4, 2.241(5); Au1-Au2a, 3.287-
(1); Au1-S1-Au2, 82.8(1); Au1-S1-C01, 104.6(5); Au2-S1-C01,
105.6(6); P1-Au1-S1, 172.8(2); P2-Au2-S1, 175.8(1); Au3-S2-
Au4, 81.7(1); Au3-S2-C02, 108.0(6), Au4-S2-C02 110.0(6), P3-
Au3-S2 174.5(1), P4-Au4-S2 170.1(2); Au2-Au1-Au2a, 87.8(1).
Figure 2. Part of a chain of {[(Ph3P)Au]2S(CH2)5S[Au(PPh3)]2}2+
dications in the lattice of 3 (ORTEP, carbon atoms and hydrogen atoms
omitted for clarity). Selected distances [Å] and angles [deg]: Au1-
Au2a, 3.225(1); Au3-Au4a, 3.349(1); Au2-Au1-Au2a, 86.5(1);
Au4-Au3-Au4a, 90.7(1).
Racemic 1,2-dithioglycerol also affords a tetranuclear auration
product 4 (eq 3), which could be isolated as colorless single
crystals of limited stability in low yield. The X-ray diffraction
analysis revealed a structure in which the dications are associated
only into dimers (Figure 3). The terminal bifurcated S(AuL)2
units form centrosymmetrical tetranuclear units, while those at
the central carbon atom of the glycerol are not engaged in
intermolecular contacts. Such contacts are probably prevented
by the neighboring CH2OH group, the position of which is
disordered in the crystal.
Figure 4. Structure of the cation in the crystal of {[(Ph3P)Au]S-
-
CH2CHS[Au(PPh3)]CH2S[Au(PPh3)]2}+BF4 6 (ORTEP, except for
phenyl carbon atoms; hydrogen atoms omitted for clarity). Selected
distances [Å] and angles [deg]: Au1-Au2, 3.201(1); Au2-Au3, 3.227-
(1); Au3-Au4, 3.178(1); Au1-S1, 2.296(3); Au2-S1, 2.597(2); Au2-
S2, 2.399(2); Au3-S2, 2.328(2); Au4-S3, 2.285(2); Au1-P1, 2.247-
(3); Au2-P2, 2.248(2); Au3-P3, 2.255(2); Au4-P4, 2.254(2); Au1-
S1-Au2, 81.5(1); Au1-S1-C1, 103.0(3); Au2-S1-C1, 97.1(3);
Au2-S2-C2, 103.8(3); P1-Au1-S1, 175.5(1); P2-Au2-S1, 123.7-
(1); P2-Au2-S2, 149.1(1); Au2-S2-Au3, 86.1(1); Au3-S2-C2,
102.7(3); P3-Au3-S2, 169.3(1); Au4-S3-C3, 101.7(3); P4-Au4-
S3, 176.8(1).
HOCH2(CHSH)CH2SH + [(Ph3P)Au]3O+BF4- f H2O +
-
{HOCH2HCS[(Ph3P)Au]2CH2S[Au(PPh3)]2}2+(BF4 )2 (4)
-55 °C, where a single sharp resonance is obtained. The ground
state structure is assumed to be similar to that of the trinuclear
dithioglycol complex (B, below).
(3)
With a different stoichiometry of the reagents, a trinuclear
complex of racemic 1,2-dithioglycerol can also be obtained (5,
eq 4). The product has been identified by standard analytical
and spectroscopic data, but it could not be crystallized.
Variable-temperature 31P NMR spectra showed that the com-
pound is fluxional in solution referring to a rapid site exchange
of the gold phosphine units at the sulfur centers. This process
appears to be rapid on the NMR time scale in solution even at
HOCH2(CHSH)CH2SH + [(Ph3P)Au]3O+BF4- f
+
H
2O + {[HOCH2(CHS)CH2S][Au(PPh3)]3} BF4- (5) (4)
Trithioglycerol forms a tetranuclear complex in good yield (6,
eq 5) with a distinctly unsymmetrical distribution of the four
metal atoms over the three thiolate donor centers, as determined

3272 Inorganic Chemistry, Vol. 35, No. 11, 1996
Sladek and Schmidbaur
by X-ray diffraction (Figure 4). Note that a symmetrical
structure (A) is possible for this cation (with a mirror plane or
a 2-fold axis), but this is not what is found in the lattice of the
tetrafluoroborate salt. However, the structure is reminiscent of
the configuration described for the trinuclear dithioglycol
complex (B).
Conclusions. The present study has shown that polythiol
molecules can readily be converted into polynuclear [(phos-
phine)aurio]sulfonium salts with mono- or diaurated sulfur
centers. The distribution of the gold atoms can be symmetrical
and/or asymmetrical, and in solution a rapid site exchange can
lead to a redistribution of the metal atoms over the sulfur donor
sites. The ground state structures, as determined by crystal
structure analysis, feature distinct intramolecular gold-gold
+
contacts at the diaurated sulfonium centers or between S(AuL)2 -
and S(AuL) units. In sterically favorable cases two of the
bifurcated terminal S(AuL)2+ units can aggregate through double
Au-Au contacts to form novel auriophilicity-determined su-
pramolecular systems, as first detected here for compound 3.
There is reason to believe that other classes of polynuclear gold-
(I) complexes will give rise to similar phenomena.
HSCH2(CHSH)CH2SH + [(Ph3P)Au]3O+BF4- f
H2O + {[SCH2(CHS)CH2S][Au(PPh3)]4}+BF4- (6) (5)
Acknowledgment. This work was supported by the Deutsche
Forschungsgemeinschaft and Fonds der Chemischen Industrie.
The authors are indebted to Mr. J. Riede for carefully establish-
ing the X-ray data sets.
As shown by variable-temperature NMR spectroscopy, the
structure of 5 is not rigid in solution (dichloromethane), but
has to be taken as fluxional. The rapid site exchange of the
AuL units leads to pseudosymmetry on the NMR time scale at
ambient temperature, rendering all phosphine units equivalent.
The two glycerol CH2 groups are also found to be pseu-
doequivalent under these conditions.
Supporting Information Available: Tables of atomic coordinates
and thermal parameters, hydrogen atom parameters, and bond distances
and angles (78 pages). Ordering information is given on any current
masthead page.
IC9516119