Mesitylgold(I) and silver(I) perfluorocarboxylates as precursors of supramolecular Au/Ag systems

Article abstract of DOI:10.1021/om060413u

Reaction of [Ag(CF₃CO₂)] with tetrahydrothiophene (tht) (2:1) in dichloromethane leads to the synthesis of [Ag₄(CF ₃CO₂)₄(tht)₂] (1), which further reacts with mesitylgold(I) ([A

Full text of DOI:10.1021/om060413u

Organometallics 2006, 25, 4307-4315
4307
Mesitylgold(I) and Silver(I) Perfluorocarboxylates as Precursors of
Supramolecular Au/Ag Systems
Eduardo J. Ferna´ndez,*,§ Antonio Laguna,*,‡ Jose´ M. Lo´pez-de-Luzuriaga,§ M. Montiel,§
M. Elena Olmos,§ Javier Pe´rez,§ and Raquel C. Puelles§
Departamento de Qu´ımica, UniVersidad de la Rioja, Grupo de S´ıntesis Qu´ımica de La Rioja, UA-CSIC,
Complejo Cient´ıfico Tecnolo´gico, 26006 Logron˜o, Spain, and Departamento de Qu´ımica Inorga´nica,
Instituto de Ciencia de Materiales de Arago´n, UniVersidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
ReceiVed May 15, 2006
Reaction of [Ag(CF3CO2)] with tetrahydrothiophene (tht) (2:1) in dichloromethane leads to the synthesis
of [Ag4(CF3CO2)4(tht)2] (1), which further reacts with mesitylgold(I) ([Au(mes)]) (1:1) to afford
[AuAg4(mes)(CF3CO2)4(tht)]n (3). Treatment of [Au(mes)] with [Ag(RCO2)] (R ) CF3, CF2CF3) and tht
(molar ratio 1:4:1 or 1:4:3) leads to the new Au/Ag systems [AuAg4(mes)(RCO2)4(tht)x]n (x ) 1, R )
CF3 (3), CF2CF3 (4); x ) 3, R ) CF3 (5), CF2CF3 (6)). The crystal structures of 3, 4, and 6 have been
established by X-ray diffraction, all of them displaying Au‚‚‚Ag interactions supported by mesityl ligands
that bridge three metal centers in an unprecedented situation in transition metal chemistry. Additional
Au-S-Ag and Ag-O-Ag (3 and 4) or Ag-S-Ag (6) bonds result in two-dimensional polymers that
contain both Au‚‚‚Ag and Ag‚‚‚Ag contacts. Treatment of 3 with water (1:2) in dichloromethane leads
to {[AuAg4(mes)(CF3CO2)4(tht)(H2O)]‚H2O‚CH2Cl2}n (7), whose crystal structure shows the partial break
of the cyclic [Ag2(µ-RCO2)2] dimer present in the structures of 3, 4, and 6, probably caused by the
coordination of one molecule of water to one of the AgI centers. It also displays Au‚‚‚Ag and Ag‚‚‚Ag
interactions, as well as Ag-C bonding interactions and additional Ag-O contacts, which result in a
monodimensional polymer. The crystal structure of 1 has also been determined by X-ray diffraction.
On the other hand, donor-free silver(I) perfluorocarboxylates
have been shown to often crystallize forming cyclic dimers of
the type [Ag(µ-O,O′-RCO2)]2 with planar eight-membered rings
that display intramolecular Ag‚‚‚Ag interactions.5 This dimeric
unit can also be kept as a core in complexes with neutral donor
ligands, either preserving2a,6 or losing7 the metallophilic con-
tacts, or even in AuI/AgI compounds, such as in the tetra-
nuclear [{(4-Me2NC6H4)Ph2PAu(OCOC2F5)}2(AgC2F5CO2)2]2a
or [{(C6F5)Au(PPh2CH2SPh)}2(AgCF3CO2)2],2b which displays
both Au‚‚‚Ag and Ag‚‚‚Ag interactions. By contrast, in the
pyramidal complex [NBu4]2[AuAg4(3,5-C6F3Cl2)2(CF3CO2)5]
Introduction
Although aurophilic Au(I)‚‚‚Au(I) interactions are the most
studied among nonbonding contacts between closed-shell met-
als,1 a number of species displaying Au(I)‚‚‚Ag(I) interactions
have been recently described. Most of them are complexes that
contain bidentate ligands between AuI and AgI,2 but there are
also compounds in which such interactions are supported only
by aryl bridging ligands3 or even a number of examples that
display unsupported Au‚‚‚Ag interactions.4 Among the latter,
additional intermolecular Au‚‚‚Au contacts can also be found,
as in [Au2Ag2(C6F5)4L2] (L ) SC4H8, C6H6)4a,b or in {Ag([Au-
(µ-C2,N3-bzim)]3)2}BF4 (bzim ) 1-benzylimidazolate),4c,d re-
sulting in the formation of monodimensional polymers in the
solid state.
(3) (a) Contel, M.; Jime´nez, J.; Jones, P. G.; Laguna, A.; Laguna, M. J.
Chem. Soc., Dalton Trans. 1994, 2515. (b) Contel, M.; Garrido, J.; Gimeno,
M. C.; Jones, P. G.; Laguna, A.; Laguna, M. Organometallics 1996, 15,
4939. (c) Cerrada, E.; Contel, M.; Valencia, A. D.; Laguna, M.; Gelbrich,
T.; Hursthouse, M. B. Angew. Chem., Int. Ed. 2000, 39, 2353. (d) Ferna´ndez,
E. J.; Gimeno, M. C.; Laguna, A.; Lo´pez-de-Luzuriaga, J. M.; Monge, M.;
Pyykko¨, P.; Sundholm, D. J. Am. Chem. Soc. 2000, 122, 7287. (e)
Ferna´ndez, E. J.; Laguna, A.; Lo´pez-de-Luzuriaga, J. M.; Monge, M.;
Montiel, M.; Olmos, M. E.; Pe´rez, J.; Puelles, R. C.; Sa´enz, J. C. J. Chem.
Soc., Dalton Trans. 2005, 1162.
(4) (a) Uso´n, R.; Laguna, A.; Laguna, M.; Jones, P. G.; Sheldrick, G.
M. Chem. Commun. 1981, 1097. (b) Uso´n, R.; Laguna, A.; Laguna, M.;
Jones, P. G.; Sheldrick, G. M. J. Chem. Soc., Dalton Trans. 1984, 285. (c)
Burini, A.; Bravi, R.; Fackler, J. P., Jr.; Galassi, R.; Grant, T. A.; Omary,
M. A.; Pietroni, B. R.; Staples, R. J. Inorg. Chem. 2000, 39, 3158. (d) Burini,
A.; Fackler, J. P., Jr.; Galassi, R.; Pietroni, B. R.; Staples, R. J. Chem.
Commun. 1998, 95. (e) Contel, M.; Garrido, J.; Gimeno, M. C.; Laguna,
M. J. Chem. Soc., Dalton Trans. 1998, 1083. (f) Uso´n, R.; Laguna, A.;
Laguna, M.; Uso´n, A.; Jones, P. G.; Erdbrugger, C. F. Organometallics
1987, 6, 1778. (g) Schuster, O.; Monkowius, U.; Schmidbaur, H.; Ray, R.
S.; Kru¨ger, S.; Ro¨sch, N. Organometallics 2006, 25, 1004.
* To whom correspondence should be addressed. E-mail: alaguna@
unizar.es; eduardo.fernandez@dq.unirioja.es.
§ Universidad de la Rioja.
‡ Universidad de Zaragoza-CSIC.
(1) (a) Gold: Progress in Chemistry, Biochemistry and Technology;
Schmidbaur, H., Ed.; John Wiley & Sons: New York, 1999. (b) Schmidbaur,
H. Nature 2001, 413, 31. (c) Schmidbaur, H. Gold Bull. 1990, 23, 11.
(2) (a) Ro¨mbke, P.; Schier, A.; Schmidbaur, H.; Cronje, S.; Raubenhe-
imer, H. Inorg. Chim. Acta 2004, 357, 235. (b) Ferna´ndez, E. J.; Lo´pez-
de-Luzuriaga, J. M.; Monge, M.; Rodr´ıguez, M. A.; Crespo, O.; Gimeno,
M. C.; Laguna, A.; Jones, P. G. Chem. Eur. J. 2000, 6, 636. (c) Wang,
Q.-M.; Lee, Y.-A.; Crespo, O.; Deaton, J.; Tang, C.; Gysling, H. J.; Gimeno,
M. C.; Larraz, C.; Villacampa, M. D.; Laguna, A.; Eisenberg, R. J. Am.
Chem. Soc. 2004, 126, 9488. (d) Olmos, M. E.; Schier, A.; Schmidbaur, H.
Z. Naturforsch. 1997, 52b, 203. (e) Crespo, O.; Ferna´ndez, E. J.; Gil, M.;
Gimeno, M. C.; Jones, P. G.; Laguna, A.; Lo´pez-de-Luzuriaga, J. M.; Olmos,
M. E. J. Chem. Soc., Dalton Trans. 2002, 1319. (f) Catalano, V. J.; Horner,
S. J. Inorg. Chem. 2003, 42, 8430. (g) Catalano, V. J.; Malwitz, M. A.;
Etogo, A. O. Inorg. Chem. 2004, 43, 5714. (h) Rawashdeh-Omary, M. A.;
Omary, M. A.; Fackler, J. P., Jr. Inorg. Chim. Acta 2002, 334, 376. (i)
Vicente, J.; Chicote, M. T.; Lagunas, M. C.; Jones, P. G. J. Chem. Soc.,
Chem. Commun. 1991, 1730. (j) Vicente, J.; Chicote, M. T.; Lagunas, M.
C. Inorg. Chem. 1993, 32, 3748.
(5) (a) Griffin, R. G.; Ellet, J. D.; Mehring, M.; Bullitt, J. G.; Waugh, J.
S. J. Chem. Phys. 1972, 57, 2147. (b) Karpova, E. V.; Boltalin, A. I.;
Korenev, Yu. M.; Troyanov, S. I. Coord. Chem. 1999, 25, 70. (c) Blakeslee,
A. E.; Hoard, J. L. J. Am. Chem. Soc. 1956, 78, 3029. (d) Paramonov, S.
E.; Mychlo, E. V.; Troyanov, S. I.; Kuz’mina, N. P. Zh. Neorg. Khim. 2000,
45, 2003.
10.1021/om060413u CCC: $33.50 © 2006 American Chemical Society
Publication on Web 07/26/2006

4308 Organometallics, Vol. 25, No. 18, 2006
Ferna´ndez et al.
Scheme 1. Synthesis of Complexes 1-7
prepared by reaction of NBu4[Au(3,5-C6F3Cl2)2] with [Ag(CF3-
CO2)] and NBu4(CF3CO2) (1:4:1),3e also containing Au‚‚‚Ag
and Ag‚‚‚Ag contacts, the silver atoms and the trifluoroacetate
anions present a different disposition giving rise to a 19-
membered bicycle with the silver centers forming the base of a
square pyramid (the gold(I) atom occupies the apical position).
Even in the absence of a heterometal, a change in the dimeric
structure of the [Ag(RCO2)]2 unit can occur during the reaction
with a neutral substrate, as observed in the recently described
complex [(Ph3PS)4(AgO2CCF3)6],6f which displays a 24-
membered metallacycle containing six silver(I) centers and six
carboxylate OCO units.
Considering all these precedents, we wondered if we could
obtain heterometallic AuI/AgI systems with Au‚‚‚Ag interactions
by reaction of a gold(I) substrate with silver perfluorocarboxy-
lates. The pentameric [Au(mes)]5 (mes ) 2,4,6-C6H2Me3) was
selected as gold starting material considering that the mesityl
groups could facilitate the presence of Au‚‚‚Ag contacts, due
to the capability of mesityl to act as bridging ligand, and that it
could lead to a novel and interesting structural situation.
We were also interested in the study of the factors that can
influence the retention of the cyclic dinuclear core [Ag(µ-O,O′-
RCO2)]2 in the resulting complexes, and for this reason, we
carried out the reaction of [Au(mes)]5 with [Ag(RCO2)] (R )
CF3, CF2CF3) in the presence or absence of a neutral donor
ligand, such as tetrahydrothiophene (tht) or water, and in
different solvents and molar ratios. We also studied the reaction
of [Ag(CF3CO2)] with tht in different molar ratios in order to
determine if the eight-membered ring is maintained.
solid, whose analytical and spectroscopic data agree with the
incorporation of half a molecule of tetrahydrothiophene per
silver atom (see Scheme 1). Thus, its IR spectrum shows, among
others, absorptions at 1663 (vs, br) and 1209 (vs, br) cm-1 due
to the trifluoroacetate anions and at 1263 (vs) cm-1 characteristic
of the tht molecules. The 19F and 1H NMR spectra of 1
corroborate the presence of both anionic and neutral ligands,
respectively, the former displaying a singlet at -73.5 ppm and
the latter two multiplets at 3.13 and 2.07 ppm.
Finally, by slow diffusion of hexane into a solution of 1 in
dichloromethane single crystals of 1 adequate for X-ray dif-
fraction studies were obtained, which show that the dimeric unit
present in many other related complexes2a,6,7 is opened now into
a higher nuclearity one. The crystal structure of 1 is shown in
Figures 1 and 2, in which a 18-membered bicycle can be
observed with the four silver atoms in a butterfly disposition
bridged by the trifluoroacetate anions and the sulfur atom of
Results and Discussion
Reaction of [Ag(CF3CO2)] with tht (2:1) in dichloromethane
leads to the synthesis of [Ag4(CF3CO2)4(tht)2] (1) as a white
Figure 1. Molecular structure of complex 1 with the labeling
scheme of the atom positions. Hydrogen atoms have been omitted
for clarity.
(6) (a) Powell, J.; Horvath, M. J.; Lough, A.; Phillips, A.; Brunet, J. J.
Chem. Soc., Dalton Trans. 1998, 637. (b) Che, C.-M.; Tse, M.-C.; Chan,
M. C. W.; Cheung, K.-K.; Phillips, D. L.; Leung, K.-H. J. Am. Chem. Soc.
2000, 122, 2464. (c) Tsuchiya, T.; Shimizu, T.; Hirabayashi, K.; Kamigata,
N. J. Org. Chem. 2002, 67, 6632. (d) Brandys, M. C.; Puddephatt, R. J. J.
Am. Chem. Soc. 2002, 124, 3946. (e) Brammer, L.; Burgard, M. D.;
Eddleston, M. D.; Rodger, C. S.; Rath, N. P.; Adams, H. Cryst. Eng.
Commun. 2004, 44, 239. (f) Djordjevic, B.; Schuster, O.; Schmidbaur, H.
Inorg. Chem. 2005, 44, 673. (g) Zhong, J. C.; Munakata, M.; Maekawa,
M.; Kuroda-Sowa, T.; Suenaga, Y.; Konaka, H. Inorg. Chim. Acta 2003,
342, 202. (h) Schultheiss, N.; Powell, D. R.; Bosch, E. Inorg. Chem. 2003,
42, 5304. (i) Bosch, E.; Barnes, C. L. Inorg. Chem. 2002, 41, 2543. (j)
Awaleh, M. O.; Badia, A.; Brisse, F.; Bu, X.-H. Inorg. Chem. 2006, 45,
1560.
(7) (a) Blues, E. T.; Drew, M. G. B.; Femi-Onadeko, B. Acta Crystallogr.
1977, B33, 235. (b) Iyoda, M.; Horino, T.; Takahashi, F.; Hasegawa, M.;
Yoshida, M.; Kuwatani, Y. Tetrahedron Lett. 2001, 42, 6883. (c) Konaka,
H.; Wu, L. P.; Munakata, M.; Kuroda-Sowa, T.; Maekawa, M.; Suenaga,
Y. Inorg. Chem. 2003, 42, 1928. (d) Munakata, M.; Liu, S. Q.; Konaka,
H.; Kuroda-Sowa, T.; Suenaga, Y.; Maekawa, M.; Nakagawa, H.; Yamazaki,
Y. Inorg. Chem. 2004, 43, 633.
Figure 2. Molecular structure of complex 1 viewed down the 4-fold
screw axis. Hydrogen atom have been omitted for clarity.

Mesitylgold(I) and SilVer(I) Perfluorocarboxylates
Organometallics, Vol. 25, No. 18, 2006 4309
the neutral tht ligands. Complex 1 crystallizes in the I41/a space
group of the tetragonal system with four molecules in the unit
cell and only a quarter of a molecule residing in the asymmetric
unit. The neighboring silver centers maintain Ag‚‚‚Ag contacts
of 3.2856 (5) Å, longer than those found in most of the structures
of complexes of the type [Ag2(RCO2)2Ln] (n ) 1, 2) that display
such contacts (from 2.8669(9) to 3.3813(6) Å).6 The trifluoro-
acetate anions are asymmetrically bridging two silver atoms,
showing Ag-O bond distances of 2.921(3) and 2.416(3) Å,
similar to what is observed in [Ag2(µ-O2CCF3)2(µ-dcpm)] (dcpm
) bis(dicyclohexylphsophino)methane),6b which displays a short
(2.191(3) Å) and a long (2.446(4) Å) Ag-O bond distance.
Finally, the Ag-S bond distance of 2.4421(8) Å compares well
with those found in [Au2Ag2(C6F5)4(SC4H8)2]n4a,b (2.454(4) Å)
8
and [NBu4][{Pt(C6F5)2}2(µ-C6F5)2{µ-Ag(SC4H8)}]‚0.5C6H14
(2.421(3) Å), which contain terminal tht molecules, and is
shorter than the Ag-S distances observed in [Ag(O3SCF3)-
Figure 3. Part of the polymeric structure of complex 3 with the
labeling scheme of the atom positions. Hydrogen and fluorine atoms
have been omitted for clarity.
9
(SC4H8)]n (2.4897(9) and 2.4963(9) Å), [{(Ph3P)Au(µ-mes)-
3a
Ag(SC4H8)}2][SO3CF3]2 (2.8245(6) Å), and [NBu4][Pt2Ag-
(C6F5)6(µ-SC4H8)2]10 (2.778(2) and 2.547 Å), in which the tht’s
act as bridging ligands, as in complex 1.
By contrast, a different result is obtained when there is a
neutral ligand, such as tht, present in the reaction medium. Thus,
when mesitylgold(I) is treated with [Ag4(CF3CO2)4(tht)2] (1)
(1:1) in dichloromethane, a new compound of stoichiometry
[AuAg4(mes)(CF3CO2)4(tht)]n (3) is isolated as a pale yellow
solid. This implies the loss of one molecule of tetrahy-
drothiophene from the starting product 1. In accordance with
this, the same product 3 can be prepared in one step by reaction
of [Au(mes)] with [Ag(CF3CO2)] and tht (1:4:1) (Scheme 1).
The FT-IR spectrum of compound 3 shows absorptions arising
from the three types of ligands: tetrahydrothiophene, mesityl,
and trifluoroacetate. Its 1H NMR spectrum confirms the presence
of both tht and mesityl ligands in a 1:1 molar ratio, showing
two multiplets at 3.13 and 2.07 ppm for the methylenic hydrogen
atoms of the tetrahydrothiophene and three singlets at 2.30, 2.47,
and 6.98 ppm for the protons of the mesityl group. The latter
are significantly shifted compared with those described for
complex 2 and mesitylgold(I), where they appear at 2.17, 2.84,
and 6.98 ppm (2) and at 2.15, 2.63, and 6.76 ppm ([Au(mes)]).
This could be due to the coordination of a molecule of tht trans
to the mesityl group in 3, which is neither present in complex
2 nor in mesitylgold(I), or to a different structural arrangement
for the mesityl groups and gold centers in both cases. Regarding
the 19F NMR spectrum of 3, it shows a unique singlet, which
suggests the equivalence of all the trifluoroacetate anions in
solution. As in the case of complex 2, its mass spectrum (ES-)
suggests an oligomeric or polymeric nature for 3, displaying
peaks at m/z 775 and 870, corresponding to the fragments
[Ag3(CF3CO2)4]- and [AuAg2(mes)(CF3CO2)3]-, respectively.
Finally, the crystal structure of 3 was determined by X-ray
diffraction methods from single crystals obtained by slow
diffusion of hexane into a solution of 3 in dichloromethane. It
can be described as decanuclear [AuAg4(mes)(CF3CO2)4(tht)]2
units formed by two [Au(mes)(tht)] and four [Ag2(CF3CO2)2]
fragments linked via Au-Ag, Ag-S, and Ag-C bonding
interactions, as shown in Figure 3. The repetition of such
decanuclear units joined together through additional Ag-O
contacts of 2.429(3), 2.518(3), and 2.516(3) Å gives rise to a
two-dimensional polymer (Figure 4). As is foreseeable, these
Ag-O distances are longer than those found within the
[Ag2(CF3CO2)2] units, which range from 2.151(3) to 2.367(3)
Å. Both the dimers and the intramolecular Ag‚‚‚Ag interactions
are kept in the crystal structure of 3, showing Ag-Ag distances
(2.9149(5) and 2.9754(5) Å) that compare well with those found
in complexes of the type [Ag2(RCO2)2Ln] (n ) 1, 2) that display
We tried then to synthesize other compounds with different
proportions of tht, but when the same reaction is carried out in
different molar ratios or compound 1 is treated with an excess
of tht, the same complex (1) is isolated or no reaction is
observed, respectively.
On the other hand, when [Ag(CF3CO2)] is treated with
equimolecular amounts of mesitylgold(I) in dichloromethane and
in the absence of tht, the new complex [AuAg(mes)(CF3CO2)]
(2) is isolated from the solution as a dark green powder. The
same solid is always formed when the reaction is carried out in
different molar ratios of the reagents, when donor solvents, such
as acetone or tetrahydrofuran, are employed, or when the solvent
is not distilled and dehydrated. Its analytical and spectroscopic
data agree with the proposed formulation, and thus, its IR
spectrum shows absorptions arising from the mesityl group at
1592 (s) and 851 (s) cm-1 and from the trifluoroacetate at 1658
(vs, br) and 1186 (vs, br) cm-1. The former appear at
wavelengths nearly identical to those corresponding to the
starting complex [Au(µ-mes)]5, while the latter are similar to
those described above for complex 1 and suggest the presence
of coordinated trifluoroacetate anions. The presence of the
mesityl group is also confirmed in its 1H NMR spectrum, which
displays two singlets located at 2.17 and 2.84 ppm for the
hydrogen atoms of the methyl substituents in para and ortho
positions and a third singlet at 6.89 ppm, due to the protons
located in the meta positions. These positions, similar to those
of the starting complex [Au(µ-mes)]5 (2.15, 2.63, and 6.76 ppm),
suggest the presence of the mesityl group acting as a bridging
ligand and a similar structural disposition for the gold atoms
and mesityl groups in solution in both cases. Regarding its 19
F
NMR, it is very similar to that of compound 1, showing a singlet
at -73.2 ppm, which seems to indicate a similar behavior of
the anions in both complexes. Although our efforts to obtain
single crystals of 2 to determine its structure in the solid state
were unsuccessful, its mass spectrum (ES-) suggests an, at
least, oligomeric nature for this complex, displaying, among
others, a peak at m/z ) 870, which corresponds to the unit
[Ag2Au(mes)(CF3CO2)3]-.
(8) Casas, J. M.; Fornie´s, J.; Mart´ın, A.; Menjo´n, B.; Toma´s, M.
Polyhedron 1996, 15, 3599.
(9) Bardaj´ı, M.; Crespo, O.; Laguna, A.; Fischer, A. K. Inorg. Chim.
Acta 2000, 304, 7.
(10) Uso´n, R.; Fornie´s, J.; Falvello, L. R.; Toma´s, M.; Casas, J. M.;
Mart´ın, A. Inorg. Chem. 1993, 32, 5212.

4310 Organometallics, Vol. 25, No. 18, 2006
Ferna´ndez et al.
Apart from the mesityl, the sulfur atom of the tht also acts
as a bridge between a Au(I) center and a Ag(I) atom, thus
forming, together with one of the Au‚‚‚Ag contacts, hexanuclear
Ag2Au2S2 rings (see Figure 3). It is worth mentioning that,
although there are a number of compounds with tetrahy-
drothiophene bridging two metals, complex 3 is the first case
in which this ligand acts as a bridge between gold and any other
metal, and there are a few structures with tht bonded to gold
and none of them contain an aryl or alkyl group as ligand.12
The Au-S distance in 3 (2.3195(11) Å) is similar to those
observed in complexes with tht trans to a neutral ligand, such
12a
as {[Au(tht)2][AuI2]}n (2.335(6) and 2.30(7) Å), [Au(tht)2]-
12c
(o-C6H4(SO2)2N)12b (2.295 Å), or [Au(tht)(PPh2py)]ClO4
(2.321(2) Å), but longer than the Au-S bond lengths found in
those that have an anionic ligand trans to tht, such as [Au-
{N(SO2R)2}(tht)] (R ) CH3, p-C6H4Cl, p-C6H4I)12d (2.237-
2.263 Å) or [AuX(tht)] (X ) Cl, Br)12e (2.279 and 2.256 Å).
The Ag-S distance of 2.6877(11) Å shows a weaker bond than
Figure 4. Polymeric layer structure of complex 3. Hydrogen and
fluorine atoms, as well as the carbon atoms of the tht and mes
ligands (except the ipso carbon), have been omitted for clarity
reasons. Hexanuclear Ag2Au2S2 rings are marked in black and Ag-
O-Ag bridges in red.
9
in complex 1 (2.4421(8) Å) or in [Ag(O3SCF3)(SC4H8)]n
(2.4897(9) and 2.4963(9) Å), but is shorter than that described
for the related complex [{(Ph3P)Au(µ-mes)Ag(SC4H8)}2][SO3-
CF3]23a (2.8245(6) Å), in which the tht acts as a bridge between
two silver(I) atoms, or in [NBu4][Pt2Ag(C6F5)6(µ-SC4H8)2]10
(2.778(2) and 2.547 Å).
such contacts (2.8669(9)-3.3813(6) Å).6 Each gold center is
linearly coordinated to the ipso carbon atom of a mesityl group
and to the sulfur of a tht ligand with typical Au-C and Au-S
bond distances of 2.045(4) and 2.3195(11) Å, respectively, and
maintain short Au‚‚‚Ag contacts of different magnitude (2.8226(4)
and 2.8993(4) Å) with two neighboring silver centers. The
former is nearly identical to the Au-Ag distance of 2.8245(6)
Å found in the related mesityl derivative [{(Ph3P)Au(µ-mes)-
Ag(tht)}2][SO3CF3]2,3a in which both metals are also bridged
by a mesityl ligand, or in the dinuclear complex [AuAg(PPh2-
py)2(OClO3)2]2d (2.820(1) Å), where the metal centers are
doubly bridged by diphenylphosphinopyridine. The Au‚‚‚Ag
interactions in 3 are in general weaker than in most of the
complexes containing aryl bridging ligands between gold and
silver (2.7758(8)-2.8245(6) Å),3a-d with the only exception of
(NBu4)2[Au(3,5-C6F3Cl2)2Ag4(CF3CO2)5],3e where the Au-Ag
distances range from 2.9010(6) to 3.0134(6) Å.
Similarly, treatment of [Au(mes)] with [Ag(CF3CF2CO2)] and
tht (1:4:1) affords a complex of stoichiometry [AuAg4(mes)(CF3-
CF2CO2)4(tht)]n (4) (Scheme 1). Its FT-IR spectrum resembles
that of complex 3, and also its 1H NMR spectrum is very similar
to that mentioned above for 3 and confirms the presence of tht
and mesityl in equimolecular amounts displaying two multiplets
at 3.16 and 2.10 ppm for the hydrogen atoms of tht and three
singlets at 2.32, 2.46, and 7.00 ppm for the protons of the mesityl
group. The perfluoropropionate anions are also detected as
equivalent in solution in the 19F NMR spectrum of 4, which
displays two singlets at -83.2 and -118.8 ppm. A certain
degree of association is also suggested, as in previous cases, in
its mass spectrum (ES-), which displays peaks at m/z 433, 704,
and 977, corresponding to the fragments [Ag(CF3CF2CO2)2]-,
[Ag2(CF3CF2CO2)3]-, and [Ag3(CF3CF2CO2)4]-, respectively.
It is worth noting that although there are some examples of
compounds with aryl groups acting as bridges between two
metal atoms though the ipso carbon of the aryl ligand3 (see Chart
1, A) or even as a bridge between three group-8 metal centers
as shown in Chart 1, B,11 interestingly, the ipso carbon atom of
the mesityl ligand in 3 bridge three metals (see Chart 1, C),
which is an unprecedented situation in transition metal chem-
istry. Thus, the ipso carbon atom binds the gold center and two
silver atoms, showing longer Ag-C distances (2.614(4) and
2.530(4) Å) than those observed in the rest of complexes
containing aryl bridging ligands between AuI and AgI (in the
range 2.27(2)-2.506(8) Å),3 in which the ipso carbon atom
binds two instead of three metals. In contrast, the Au-C distance
of 2.045(4) Å observed in 3 is oddly shorter than those found
in the same related complexes (2.067(7)-2.200(7) Å).3
Finally, its crystal structure was established by X-ray dif-
fraction from single crystals obtained by slow diffusion of
hexane into a solution of 4 in dichloromethane. It is shown in
Figures 5 and 6, which show a crystal structure similar to that
described above for compound 3 consisting of decanuclear
[AuAg4(mes)(CF3CF2CO2)4(tht)]2 units linked together through
Ag-O contacts, resulting in a two-dimensional polymer normal
to the crystallographic y axis (Figure 6). As in the case of
complex 3, these Ag-O interactions, of 2.408(6), 2.417(6), and
2.532(6) Å, are longer than those found within the [Ag2(CF3-
CF2CO2)2] units (from 2.196(7) to 2.367(6) Å). The silver
centers in these dimers still maintain the Ag‚‚‚Ag interactions,
showing distances of 2.9479(10) and 2.9295(10) Å, similar to
those found in 3 or in other complexes containing the dimeric
Chart 1. Different Coordination Modes of Aryl Bridging Ligands

Mesitylgold(I) and SilVer(I) Perfluorocarboxylates
Organometallics, Vol. 25, No. 18, 2006 4311
expected for a bridging tht, it is longer than in the complexes
with gold(I) bonded to a terminal tht (2.237-2.335(6) Å)12 and
also longer than in 3 (2.3195(11) Å). The Ag-S distance of
2.888(2) Å is in this case also longer than in complexes 1
(2.4421(8) Å) and 3 (2.6877(11) Å) or in other compounds with
bridging tht.3a,9,10
The main difference between the crystal structures of 3 and
4 is located in the bonding scheme of the mesityl ligand, which,
as in 3, very interestingly bridges one gold(I) and two silver(I)
centers, although in a different and striking way (Chart 1, D):
the ipso carbon atom binds the gold center and a silver atom
(which also keep a short Au‚‚‚Ag contact) with a Ag-C of
2.532(8) Å, while the second silver(I) center is connected to
one of the meta carbon atoms of the mesityl group (Ag-C
2.650(8) Å), as shown in Figure 5. Both Ag-C distances are
of the same order as those described above for complex 3 and
also longer than in other complexes with aryl bridging ligands
between Au and Ag (type A)3 (Ag-C distances ranging from
2.27(2) to 2.506(8) Å).
Figure 5. Part of the polymeric structure of complex 4 with the
labeling scheme of the atom positions. Hydrogen and fluorine atoms
have been omitted for clarity.
In view of the interesting crystal structures found for
complexes 3 and 4, both containing tht, perfluorocarboxylate
and mesityl bridges, as well as Au‚‚‚Ag and Ag‚‚‚Ag interac-
tions, we wondered if the presence of a higher amount of
tetrahydrothiophene would give rise to different dispositions,
although, as commented above, treatment of [Ag4(CF3CO2)4-
(tht)2] (1) with mesitylgold(I) (1:1) takes place with the loss of
one molecule of tht, resulting in the formation of 3. In
accordance with this, the reaction of [Au(mes)] with [Ag(RCO2)]
(R ) CF3, CF2CF3) and tht (1:4:2) affords a mixture of [AuAg4-
(mes)(RCO2)4(tht)]n (R ) CF3 (3), CF2CF3 (4)) and another
product with a higher content of tht. In contrast, when the same
reaction is carried out with 3 mol of tht per gold(I), the new
products [AuAg4(mes)(RCO2)4(tht)3]n (R ) CF3 (5), CF2CF3
(6)) are isolated as pale yellow solids with analytical and
spectroscopic data in accordance with the proposed stoichiom-
etry (Scheme 1). Thus, their FT-IR spectra resemble those of
Figure 6. Polymeric layer structure of complex 4. Hydrogen and
fluorine atoms, as well as the carbon atoms of the tht and mes
ligands (except the ipso carbon), have been omitted for clarity
reasons. Hexanuclear Ag2Au2S2 rings are marked in black and Ag-
O-Ag bridges in red.
unit [Ag2(RCO2)2].6 There are also intermetallic Au‚‚‚Ag short
contacts of 2.8140(8) and 2.8166(8) Å connecting the [Ag2(CF3-
CF2CO2)2] fragments with the [Au(mes)(tht)] units, which, as
in 3, are in general longer than in most aryl-bridged complexes
(2.7758(8)-2.8245(6) Å).3a-d Surprisingly, the Au-Ag lengths
in 4 are nearly identical, although only one of the silver atoms
binds the ipso carbon atom of the mesityl ligand, and are shorter
than in complex 3, where two different Au-Ag distances are
observed (2.8226(4) and 2.8993(4) Å), although they should
be more symmetric considering the bonding scheme in 3 (see
Figure 3). As in the structure of 3, each gold(I) center displays
its typical linear coordination and bridging tht ligands respon-
sible of the presence of Ag2Au2S2 rings (see Figure 5). The
Au-C distance of 2.047(8) Å is almost identical to that in
complex 3 (2.045(4) Å), although the carbon atom in 4 bridges
two instead of three metal centers, and is also shorter than the
Au-C bond lengths found in related complexes (2.067(7)-
2.200(7) Å).3 Regarding the Au-S distance of 2.347(2) Å, as
1
complexes 3 and 4 (see Experimental Section), and their H
NMR spectra are very similar to those described for 3 and 4,
with relative intensities for the resonances due to tht and mesityl,
which corroborate the presence of three molecules of tht (which
are equivalent in solution) per mes ligand, as the main
difference. The perfluorocarboxylate anions are detected, also
as equivalent in solution, in their 19F NMR, which show one
(5) or two (6) singlets at -73.6 ppm or at -83.2 and -118.9
ppm, respectively. Finally, their mass spectra (ES-) display peaks
at m/z 333 and 554 (5) or at m/z 433 and 704 (6), which
correspond to the fragments [Ag(RCO2)2]- and [Ag2(RCO2)3]-,
respectively.
By slow diffusion of hexane into a solution of 6 single crystals
suitable for X-ray diffraction studies were obtained, and its
crystal structure was determined (Figures 7 and 8). The
asymmetric unit contains a [Ag2(CF3CF2CO2)2] dimer, a [Au-
(mes)(tht)] unit, and a [Ag2(CF3CF2CO2)2(tht)2] fragment, which
are connected via Au‚‚‚Ag and Ag‚‚‚C short contacts, as shown
in Figure 7. The first difference between the crystal structures
of 3 or 4 and 6 is the presence of three instead of two Au‚‚‚Ag
contacts of 2.8540(6), 2.8845(6), and 3.0782(6) Å, distances
that compare well with the Au‚‚‚Ag lengths in 3 (2.8226(4)
and 2.8993(4) Å), but are longer than in 4 (2.8140(8) and
2.8166(8) Å) and in most of the related complexes containing
aryl bridging ligands between gold and silver (2.7758(8)-
2.8245(6) Å),3a-d with the exception of (NBu4)2[Au(3,5-C6F3-
Cl2)2Ag4(CF3CO2)5],3e which presents the longest Au-Ag
distances described to date (2.9010(6)-3.0134(6) Å). Another
(11) (a) Donnecke, D.; Wunderle, J.; Imhof, W. J. Organomet. Chem.
2004, 689, 585. (b) Majeed, Z.; McWhinnie, W. R.; Paxton, K.; Hamor, T.
A. J. Chem. Soc., Dalton Trans. 1998, 3947. (c) Bhaduri, S.; Sharma, K.;
Jones, P. G. Chem. Commun. 1987, 1769. (d) Bhaduri, S.; Sharma, K.;
Khwaja, H.; Jones, P. G. J. Organomet. Chem. 1991, 412, 169. (e) Bohle,
D. S.; Vahrenkamp, H. Angew. Chem., Int. Ed. Engl. 1990, 29, 198. (f)
Al-Mandhary Muna, R. A.; Lewis, J.; Raithby, P. R. J. Organomet. Chem.
1997, 530, 247. (g) Cifuentes, M. P.; Jeynes, T. P., Humphrey, M. G.;
Skelton, B. W.; White, A. H. J. Chem. Soc., Dalton Trans. 1994, 925.
(12) (a) Ahrland, S.; Noren, B.; Oskarsson, A. Inorg. Chem. 1985, 24,
1330. (b) Friedrichs, S.; Jones. P. G. Acta Crystallogr., Sect. C: Cryst.
Struct. Commun. 2000, 56, 56. (c) Lo´pez de Luzuriaga, J. M.; Schier, A.;
Schmidbaur, H. Chem. Ber. 1997, 130, 647. (d) Ahrens, B.; Jones, P. G. Z.
Naturforsch., B: Chem. Sci. 2000, 55, 803. (e) Ahrland, S.; Dreisch, K.;
Noren, B. Oskarsson, A. Mater. Chem. Phys. 1993, 35, 281. (f) Abdou, H.
E.; Mohamed, A. A.; Fackler, J. P., Jr. Inorg. Chem. 2005, 44, 166.

4312 Organometallics, Vol. 25, No. 18, 2006
Ferna´ndez et al.
metals.3 In contrast, the Au-C distance in 6 (2.044(6) Å) shows
again a stronger interaction than in the previously described
complexes with aryl bridging ligands (Au-C distances in the
range 2.067(7)-2.200(7) Å)3 and of the same order as in com-
pounds 3 (2.045(4) Å) and 4 (2.047(8) Å). Regarding the Ag-C
distances, one of them (2.588(6) Å) compares well with the
Ag-C lengths found in complexes 3 and 4 and is longer than
the second one (2.385(6) Å), which is closer to those described
for the related complexes [{(Ph3P)Au(µ-mes)Ag(tht)}2][SO3-
CF3]23a (2.326(3) Å), [{Au(µ-mes)(AsPh3)}2Ag]ClO43b (2.27(2)
Å), [Au2Ag2(C6F5)4(OCMe2)2]n3d (2.440(8) and 2.506(8) Å), and
[NBu4]2[AuAg4(3,5-C6F3Cl2)2(CF3CO2)5]3e (2.450(6) and 2.439(6)
Å), all of them containing aryl bridging groups.
As mentioned in the Introduction, we were interested in the
study of the factors that can influence the maintenance of the
cyclic core [Ag(µ-O,O′-RCO2)]2 in the complexes obtained by
reaction of mesitylgold(I) with silver(I) perfluorocarboxylate,
the reason for which we carried out the reaction in the presence
or absence of a neutral donor ligand, such as tht or water, and
with different solvents and molar ratios. We have seen that
complexes 3-6 (in which the dimeric unit [Ag(µ-O,O′-RCO2)]2
is kept) are obtained only if dichloromethane is employed as
solvent, and there is no water present, in a 1:4 molar ratio and
in the presence of 1 (3 and 4) or 3 (5 and 6) equiv of tht. On
the other hand, when the reaction is carried out in different molar
ratios of the reagents, when donor solvents, such as acetone or
tetrahydrofuran, are employed, or when the solvent is not
distilled and dehydrated, the resulting product is always the dark
green complex [AuAg(mes)(CF3CO2)] (2). Unfortunately, we
have not been able to obtain single crystals of this compound
that could allow us to know if the dimer [Ag(RCO2)]2 is also
present in its solid state structure.
Figure 7. Part of the polymeric structure of complex 6 with the
labeling scheme of the atom positions. Hydrogen and fluorine atoms
have been omitted for clarity.
Figure 8. Polymeric layer structure of complex 6. Hydrogen and
fluorine atoms, as well as the carbon atoms of the tht and mes
ligands (except the ipso carbon), have been omitted for clarity
reasons. Octanuclear Ag4Au2S2 rings are marked in black and Ag-
S-Ag bridges in green.
Finally, we tried to study the influence of water in the reaction
and in the solid structure of the resulting complexes in order to
know if complex 2 is formed if water is present in the reaction
medium. Thus, we treated complexes 3-6 with water in
different molar ratios, but in all the cases the reaction always
leads to a green solution, which in the case of trifluoroacetate
derivatives contains compound 2, with a unique excep-
tion: when 3 is treated with water in a 1:2 molar ratio, the
color of the solution turns orange and the new complex
{[AuAg4(mes)(CF3CO2)4(tht)(H2O)]‚H2O‚CH2Cl2}n (7) is iso-
lated as a dark orange solid (Scheme 1). This implies the
incorporation of two molecules of water in the starting material
(3), which is confirmed by its analytical and spectroscopic prop-
erties. Thus, its FT-IR spectrum shows, besides the bands arising
difference is the presence of two additional tetrahydrothiophene
molecules in one of the silver(I) trifluoroacetate dimers bonded
to the Ag(I) centers with Ag-S bond distances of 2.6295(16)
and 2.7116(17) Å. These additional tht molecules seem to be
responsible for the different mode of polymerization of complex
6 compared with compounds 3 and 4: the formation of Ag-
S-Ag instead of Au-S-Ag bridges, which result in the
appearance of eight-membered Au2Ag4S2 rings, as shown in
Figure 7, and finally in a two-dimensional polymer (Figure 8).
Thus, the tht molecules bonded to silver asymmetrically bridge
two Ag(I) centers, showing Ag-S bond lengths of 2.6295(16)
and 2.7226(16) Å for S(2) and of 2.6574(17) and 2.7116(17) Å
for S(3). As in the previous complexes 3 and 4, both the dimers
and the intramolecular Ag‚‚‚Ag interactions are kept in the
crystal, showing Ag-Ag distances of 2.9169(6) and 3.0958(7)
Å, and the gold center is linearly coordinated to a mesityl group
and to a tht ligand with Au-C and Au-S bond distances of
2.044(6) and 2.3423(16) Å. The latter is nearly identical to the
Au-S bond length of 2.347(2) Å described for complex 4,
although in complex 6 the tetrahydrothiophene molecule acts
as terminal instead of as bridging ligand. It is longer than in
the complexes with gold(I) bonded to a terminal tht (2.237-
2.335(6) Å)12 and even longer than in 3 (2.3195(11) Å), in which
tht bridges two metals.
from tht, mes, and trifluoroacetate, an absorption at 3429 cm-1
,
due to the water that has been incorporated. The presence of
1
these additional molecules of water is also detected in the H
NMR spectrum of 7, showing a broad signal at 1.54 ppm, corres-
ponding to water, in addition to the resonances due to the meth-
ylenic hydrogen atoms of the tetrahydrothiophene, the protons
of the mesityl group, and those of the molecule of dichloro-
methane. It is worth noting that there is no significant shift of
the resonances corresponding to mesityl and tht compared to
those of the starting complex 3. Regarding the 19F NMR spec-
trum of 7, as in 3 it shows a unique singlet at -73.5 ppm, which
suggests the equivalence of all the trifluoroacetate anions in
solution. Finally, the mass spectrum (ES-) suggests the presence
of one molecule of water coordinated to silver, displaying
peaks at m/z 334 and 662, corresponding to the fragments
[Ag(CF3CO2)2]- and [Ag2(CF3CO2)3(tht)(OH2)]-, respectively.
As in the crystal structure of 3, the ipso carbon of the mesityl
ligand interestingly bridges one gold and two silver centers,
being, together with complex 3, the first examples of an ipso
carbon atom bridging three transition metal centers. As in 3,
this should imply a longer Au-C distance than in 4 or in other
compounds with aryl ligands bridging two instead of three
To unequivocally establish the structure of compound 7 in
the solid state, single crystals suitable for X-ray diffraction study

Mesitylgold(I) and SilVer(I) Perfluorocarboxylates
Organometallics, Vol. 25, No. 18, 2006 4313
Figure 9. Part of the polymeric structure of complex 7 with the labeling scheme of the atom positions. Hydrogen and fluorine atoms have
been omitted for clarity.
were obtained by layering a solution of 7 in dichloromethane
with hexane. As in complexes 3, 4, and 6 the asymmetric unit
contains a [Ag2(µ-CF3CO2)2] dimer and a [Au(mes)(tht)] unit,
but shows a noticeable difference: in the second [Ag2(CF3-
CO2)2] fragment the eight-membered cycle is no longer present.
This is probably caused by the coordination of one molecule
of water to one of the AgI centers with a bond distance of 2.195-
(5) Å, which is the shortest Ag-O length found in 7. Thus,
while one trifluoroacetate keeps its normal µ-η2 coordination
mode with Ag-O bond distances of 2.248(5) and 2.210(5) Å,
the second one acts as a µ3-η2 ligand with O(8) bonded to Ag-
(1) and Ag(2), showing longer Ag-O bond lengths (2.420(6)
and 2.488(6) Å), while O(7) binds to a AgI center of a
neighboring [Ag2(µ-CF3CO2)2] dimer (Ag-O 2.336(6) Å). As
in the structures described above, the fragments contained in
the asymmetric unit, [Ag2(µ-CF3CO2)2], [Au(mes)(tht)], and
[Ag2(µ-CF3CO2)(µ3-η2-CF3CO2)(OH2)], are connected via
Au‚‚‚Ag and Ag‚‚‚C short contacts, as shown in Figure 9. As
in complex 6, there are three Au‚‚‚Ag contacts of 2.8503(6),
2.8708(6), and 3.1347(7) Å, the latter being the longest described
to date in complexes containing aryl bridging ligands between
AuI and AgI (2.7758(8)-3.0134(6) Å),3 while the other two
Au-Ag lengths are close to those in complex 6 (2.8540(6) and
2.8845(6) Å).
Å, resulting in a monodimensional polymer that runs parallel
to the crystallographic y axis. As in the previous complexes 3,
4, and 6, there are intramolecular Ag‚‚‚Ag interactions in the
crystal of 2.9725(8) and 3.0515(8) Å, the latter corresponding
to the triply bridged pair of silver(I) centers Ag(1) and Ag(2).
In view of these results, we can conclude that the reaction of
mesitylgold(I) with silver(I) perfluorocarboxylates leads to
species containing Au‚‚‚Ag interactions and keeping the dimeric
cycle [Ag2(µ-RCO2)2] only if the reaction is carried out in
dichloromethane, the Au:Ag ratio is 1:4, and 1 or 3 mol of tht
per mol of gold(I) is present. Under other conditions, such as
the employment of different solvents or with dichloromethane
that is not distilled and dried or treatment of the reagents in
other molar ratios or in the absence of tht, a green solution is
obtained, from which complex 2 can be identified in the
derivatives with trifluoroacetate. Only the reaction of 3 with 2
mol of water leads to a different product, complex 7, in which
a partial breaking of the dimer is observed in the solid state,
probably caused by the incorporation of water in the coordina-
tion sphere of one of the silver(I) atoms. We tentatively suggest
that the presence of higher amounts of water or the use of a
donor solvent could lead to the total break of the cycle, which
seems to stabilize the systems.
The gold(I) atom is again almost linearly coordinated to a
mesityl group and a tht ligand, and the ipso carbon of the mesityl
ligand bridges one gold and two silver centers. Despite the
presence of tht as a terminal ligand in 7, the Au-S bond distance
of 2.3386(19) Å is of the same order as in compounds 3 and 4
(2.3195(11) and 2.347(2) Å, respectively), in which the S-donor
ligand bridges two metal centers, and longer than in other
complexes with gold(I) bonded to a terminal tht (2.237-2.335(6)
Å).12 Regarding the Au-C bond distance of 2.063(7) Å, it
compares well with those mentioned above for complexes 3, 4,
and 6 (2.045(4), 2.047(8), and 2.044(6) Å) and is nearly identical
to the Au-C distances described for [NBu4]2[AuAg4(3,5-C6F3-
Cl2)2(CF3CO2)5]3e (2.067(7) and 2.068(7) Å), all of them
containing aryl bridging groups. The Ag-C bond lengths of
2.362(6) and 2.555(6) Å are similar to those described for 6
(2.385(6) and 2.588(6) Å), which displays a very similar bonding
situation around the central AuAg2 core.
Experimental Section
Instrumentation. Infrared spectra were recorded in the range
4000-200 cm-1 on a Nicolet Nexus FT-IR Spectrum 1000
spectrophotometer using Nujol mulls between polyethylene sheets.
C, H, S analysis were carried out with a Perkin-Elmer 240C
microanalyzer. Mass spectra were recorded on a HP59987 A
Electrospray. 1H and 19F NMR spectra were recorded on a Bruker
ARX 300 in CDCl3 solutions. Chemical shifts are quoted relative
to SiMe4 (1H, external) and CFCl3 (19F, external).
General Comments. Tetrahydrothiophene, silver trifluoroacetate,
and silver pentafluoropropionate are commercially available and
were purchased from Fluka and Aldrich. The precursor complex
[Au(µ-mesityl)]513 was obtained according to literature procedures.
Synthesis of [Ag4(CF3CO2)4(tht)2] (1). To a solution of AgCF3-
CO2 (0.088 g, 0.4 mmol) in dichloromethane (20 mL) was added
tht (0.0199 g, 0.2 mmol). After 30 min of stirring the solution was
concentrated in a vacuum to ca. 5 mL. Addition of n-hexane (10
Finally, another difference between the structures of 3, 4 or
6, and 7 is found in the mode of polymerization, which in 7
takes place through Ag-O contacts of 2.477(5) and 2.336(6)
(13) Gambarotta, S.; Floriani, C.; Chiesi-Villa, A.; Guastini, C. J. Chem.
Soc., Chem. Commun. 1983, 1304.

4314 Organometallics, Vol. 25, No. 18, 2006
Table 1. Data Collection and Structure Refinement Details for Complexes 1, 3, 4, 6, and 7
Ferna´ndez et al.
1
3
4
6
7
chemical formula
C16H16Ag4F12O8S2
C21H19Ag4AuF12O8S
C25H19Ag4AuF20O8S
C33H35Ag4Au-
F20O8S3
yellow prism
0.27 × 0.25 × 0.2
monoclinic
P21/n
17.4049(2)
13.2287(2)
21.8433(3)
90
106.5940(10)
90
4819.83(11)
4
2.293
1664.24
3168
C21H21Ag4Au-
F12O9S‚H2O‚CH2Cl2
cryst habit
cryst size/mm
cryst syst
space group
a/Å
colorless prism
0.18 × 0.12 × 0.12
tetragonal
I41/a
12.9294(3)
12.9294(3)
17.3000(6)
90
yellow prism
0.35 × 0.2 × 0.15
monoclinic
P21/c
12.7175(1)
22.9632(3)
11.4802(1)
90
111.473(1)
90
3119.91(5)
4
yellow prism
0.2 × 0.15 × 0.1
triclinic
P1h
9.0739(2)
12.0061(3)
17.3606(4)
93.971(14)
91.261(13)
99.875(8)
1857.70(8)
2
dark orange prism
0.35 × 0.25 × 0.18
monoclinic
P21/c
12.7920(1)
12.7632(2)
23.0315(3)
90
105.6203(8)
90
3621.40(8)
4
b/Å
c/Å
R/deg
â/deg
90
90
γ/deg
U/Å3
2892.03(14)
4
2.434
1059.89
2016
Z
Dc/g cm-3
M
2.742
1287.87
2400
2.660
1487.91
1392
2.584
1408.83
2648
F(000)
T/°C
-100
-100
-100
-100
-100
2θmax/deg
µ(Μo KR)/mm-1
no. of reflns measd
no. of unique reflns
Rint
56
56
56
56
54
2.929
6273
1721
0.0294
0.0372
0.0941
96
7.334
29 036
7410
0.0423
0.0302
0.0620
454
106
1.029
2.682
6.208
30 644
8706
0.0621
0.0514
0.1134
535
133
1.093
2.868
2.293
68 752
11 366
0.0661
0.0448
0.0852
625
11
6.477
59 185
7630
0.0552
0.0414
0.1056
472
97
1.011
2.782
Ra (I > 2σ(I))
wRb (F2, all reflns)
no. of params
no. of restraints
Sc
0
1.170
2.145
1.046
2.623
max. ∆F/e Å-3
2
2
2
2
2
2
a R(F) ) ∑||Fo| - |Fc||/∑|Fo|. b wR(F2) ) [∑{w(Fo - Fc )2}/∑{w(Fo )2}]0.5; w-1 ) σ2(Fo ) + (aP)2 + bP, where P ) [Fo + 2Fc ]/3 and a and b are
2
2
constants adjusted by the program. c S ) [∑{w(Fo - Fc )2}/(n - p)]0.5, where n is the number of data and p the number of parameters.
Table 2. Selected Bond Lengths [Å] and Angles [deg] for
mL) was added to precipitate complex 1 as a white solid. Yield:
Complex 1a
0.0982 g (92.6%). Anal. Calcd for 1 (C16H16Ag4F12O10S2): C, 18.13;
H, 1.52; S, 6.05. Found: C, 18.32; H, 1.55; S, 6.35. FT-IR (Nujol
Ag-O(1)
Ag-S
2.192(3)
2.4421(8)
Ag-O(2)
Ag-Ag#1
2.416(3)
3.2856(5)
mulls): ν(tht) at 1263 cm-1, ν(CF3CO2) at 1663 and 1209 cm-1
.
1H NMR (75.5 MHz, CDCl3): δ 3.13 (m, 8H, S-CH2-CH2-)
and 2.07 ppm (m, 8H, S-CH2-CH2-). 19F NMR (282.4 MHz,
CDCl3): δ -73.5 ppm (s, 12F, CF3CO2). (ES-): m/z 333
[Ag(CF3CO2)2]-.
O(1)-Ag-O(2)
O(2)-Ag-S
110.49(10)
96.41(7)
O(1)-Ag-S
153.02(8)
a Symmetry transformations used to generate equivalent atoms: #1 y-1/
4, -x+1/4, -z+1/4
Synthesis of [AuAg(mes)(CF3CO2)] (2). To a dichloromethane
solution (20 mL) of [Au(mes)] (0.065 g, 0.2 mmol) was added
AgCF3CO2 (0.044 g, 0.2 mmol), and the mixture rapidly turned
green. After 30 min of stirring, the solution was concentrated in a
vacuum to ca. 5 mL, and addition of n-hexane (10 mL) led to the
precipitation of complex 2 as a dark green solid. Yield: 0.098 g
(91.2%). Anal. Calcd for 2 (C11H11AgAuF3O2): C, 24.60; H, 2.06.
Found: C, 24.48; H, 1.93. FT-IR (Nujol mulls): ν(mes) at 1592
1
at 847 cm-1, and ν(CF3CO2) at 1663 and 1209 cm-1. H NMR
(75.5 MHz, CDCl3): δ 6.98 (s, 2H, m-H ), 3.13 (m, 4H, S-CH2-
CH2-), 2.47 (s, 6H, o-Me), 2.30 (s, 3H, p-Me), and 2.07 ppm (m,
4H, S-CH2-CH2-). 19F NMR (282.4 MHz, CDCl3): δ -73.5
ppm (s, 12F, CF3CO2). (ES-): m/z 775 [Ag3(CF3CO2)4]-, 870
[AuAg2(mes)(CF3CO2)3]-.
Synthesis of [AuAg4(mes)(CF3CF2CO2)4(tht)]n (4). A dichlo-
romethane solution (20 mL) of [Au(mes)] (0.063 g, 0.2 mmol) was
treated with AgCF3CF2CO2 (0.216 g, 0.8 mmol), and then tht (0.018
mL, 0.2 mmol) was added. The solution was stirred for 30 min,
and further concentration in a vacuum and addition of 20 mL of
n-hexane led to the precipitation of 4 as a pale yellow solid. Yield:
0.271 g (91.2%). Anal. Calcd for 4 (C25H19Ag4AuF20O8S): C,
20.18; H, 1.29; S, 2.15. Found: C, 20.23; H, 1.22; S, 2.85. FT-IR
(Nujol mulls): ν(tht) at 1258 cm-1, ν(mes) at 855 cm-1, and ν(CF3-
1
and 851 cm-1 and ν(CF3CO2) at 1658 and 1186 cm-1. H NMR
(75.5 MHz, CDCl3): δ 6.89 (s, 2H, m-H), 2.84 (s, 6H, o-Me), and
2.17 ppm (s, 3H, p-Me). 19F NMR (282.4 MHz, CDCl3): δ -73.2
ppm (s, 3F, CF3CO2). (ES-): m/z 332.6 [Ag(CF3CO2)2]-, 870
[AuAg2(mes)(CF3CO2)3]-.
Synthesis of [AuAg4(mes)(CF3CO2)4(tht)]n (3). This product
can be obtained by two alternative methods. Method 1: To a
dichloromethane solution (20 mL) of [Au(mes)] (0.063 g, 0.2 mmol)
was added complex 1 (0.106 g, 0.2 mmol). After 30 min of stirring,
the solution was concentrated in a vacuum to ca. 5 mL. Addition
of n-hexane (20 mL) led to the precipitation of 3 as a pale yellow
solid, which was filtered and washed with n-hexane (2 × 5 mL) in
order to remove the remaining tht. Yield: 0.232 g (90.1%).
Method 2: A dichloromethane solution (20 mL) of [Au(mes)]
(0.063 g, 0.2 mmol) was treated with AgCF3CO2 (0.177 g, 0.8
mmol), and then tht (0.018 mL, 0.2 mmol) was added. The solution
was stirred for 30 min, and further concentration in a vacuum and
addition of 20 mL of n-hexane led to the precipitation of 3 as a
pale yellow solid. Yield: 0.243 g (94.3%). Anal. Calcd for 3
(C21H19Ag4AuF12O8S): C, 19.58; H, 1.49; S, 2.49. Found: C, 19.78;
H, 1.61; S, 2.53. FT-IR (Nujol mulls): ν(tht) at 1264 cm-1, ν(mes)
CF2CO2) at 1630 and 1217 cm-1. H NMR (75.5 MHz, CDCl3):
1
δ 7.00 (s, 2H, m-H), 3.16 (m, 4H, S-CH2-CH2-), 2.46
(s, 6H, o-Me), 2.32 (s, 3H, p-Me), and 2.10 ppm (m, 4H,
S-CH2-CH2-). 19F NMR (282.4 MHz, CDCl3): -118.8
(s, 8F, CF3CF2CO2) and -83.2 ppm (s, 12F, CF3CF2CO2). (ES-)
m/z: 433 [Ag(CF3CF2CO2)2]-, 704 [Ag2(CF3CF2CO2)3]-, 977
[Ag3(CF3CF2CO2)4]-.
Synthesis of [AuAg4(mes)(CF3CO2)4(tht)3]n (5). To a solution
of [Au(mes)] (0.063 g, 0.2 mmol) in dichloromethane (20 mL) were
added AgCF3CO2 (0.177 g, 0.8 mmol) and tht (0.054 mL, 0.6
mmol). After 30 min of stirring the solution was concentrated in a
vacuum to ca. 5 mL, and hexane (20 mL) was added to precipitate
complex 5 as a pale yellow solid (0.204 g, 69.8%). Anal. Calcd

Mesitylgold(I) and SilVer(I) Perfluorocarboxylates
Organometallics, Vol. 25, No. 18, 2006 4315
Table 3. Selected Bond Lengths [Å] and Angles [deg] for
Complex 3a
Table 5. Selected Bond Lengths [Å] and Angles [deg] for
Complex 6a
Au-C(1)
2.045(4)
Ag(3)-O(7)
Ag(3)-O(5)
Ag(3)-O(8)#2
Ag(2)-O(4)
Ag(2)-O(2)
Ag(2)-O(2)#3
Ag(4)-O(6)
Ag(4)-O(8)
Ag(4)-O(5)#4
Ag(3)-O(7)
2.281(3)
2.367(3)
2.516(3)
2.207(3)
2.283(3)
2.429(3)
2.151(3)
2.208(3)
2.518(3)
2.281(3)
Au-C(1)
2.044(6)
Ag(2)-C(1)
Ag(3)-C(1)
Ag(1)-O(4)
Ag(1)-O(1)
Ag(2)-O(2)
Ag(2)-O(3)
Ag(3)-O(5)
Ag(3)-O(7)
Ag(4)-O(8)
Ag(4)-O(6)
2.385(6)
2.588(6)
2.240(4)
2.277(5)
2.295(4)
2.328(4)
2.283(5)
2.292(4)
2.200(5)
2.215(5)
Au-S
2.3195(11)
2.8226(4)
2.8993(4)
2.9149(5)
2.9754(5)
2.6877(11)
2.614(4)
Au-S(1)
2.3423(16)
2.8540(6)
2.8845(6)
3.0782(6)
2.9169(6)
3.0958(7)
2.6295(16)
2.7116(17)
2.7226(16)
2.6574(17)
Au-Ag(1)
Au-Ag(3)
Ag(1)-Ag(2)
Ag(3)-Ag(4)
Ag(1)-S#1
Ag(1)-C(1)
Ag(3)-C(1)
Ag(1)-O(3)
Au-Ag(1)
Au-Ag(3)
Au-Ag(2)
Ag(1)-Ag(2)
Ag(3)-Ag(4)
Ag(1)-S(2)
Ag(2)-S(3)
Ag(3)-S(2)#1
Ag(4)-S(3)#2
2.530(4)
2.278(3)
C(1)-Au-S
172.15(11)
S#1-Ag(1)-Au
Au-S-Ag(1)#1
106.38(3)
118.17(4)
C(1)-Au-S(1)
Ag(1)-Au-Ag(3)
a Symmetry transformations used to generate equivalent atoms: #1
-x+2, -y+1, -z+1; #2 -x+3/2, y+1/2, -z+3/2.
173.00(17)
150.891(16)
S(2)-Ag(1)-Au
S(2)#1-Ag(3)-Au
119.70(4)
88.76(4)
a Symmetry transformations used to generate equivalent atoms: #1
-x+1, -y+2, -z; #2 x, -y+3/2, z-1/2; #3 -x+2, -y+2, -z+1; #4 x,
-y+3/2, z+1/2.
Table 4. Selected Bond Lengths [Å] and Angles [deg] for
Complex 4a
Table 6. Selected Bond Lengths [Å] and Angles [deg] for
Complex 7a
Au-C(1)
2.047(8)
2.347(2)
2.8140(8)
2.8166(8)
2.9479(10)
2.9295(10)
2.888(2)
2.532(8)
2.650(8)
2.218(6)
Ag(1)-O(1)
Ag(2)-O(2)
Ag(2)-O(3)
Ag(2)-O(7)#2
Ag(3)-O(5)
Ag(3)-O(7)
Ag(3)-O(3)#3
Ag(4)-O(8)
Ag(4)-O(6)
Ag(4)-O(6)#4
2.221(6)
2.239(6)
2.324(6)
2.408(6)
2.286(6)
2.367(6)
2.532(6)
2.196(7)
2.248(6)
2.417(6)
Au-C(1)
2.063(7)
Ag(1)-O(8)
Ag(1)-O(6)#1
Ag(2)-O(9)
Ag(2)-O(2)
Ag(2)-O(8)
Ag(3)-O(3)
Ag(3)-O(5)
Ag(4)-O(6)
Ag(4)-O(4)
Ag(4)-O(7)#2
2.420(6)
2.477(5)
2.195(5)
2.210(5)
2.488(6)
2.243(5)
2.254(5)
2.244(5)
2.256(5)
2.336(6)
Au-S(1)
Au-S
2.3386(19)
2.8503(6)
2.8708(6)
3.1347(7)
3.0515(8)
2.9725(8)
2.362(6)
Au-Ag(3)
Au-Ag(1)
Au-Ag(1)
Au-Ag(3)
Au-Ag(2)
Ag(1)-Ag(2)
Ag(3)-Ag(4)
Ag(1)-C(1)
Ag(3)-C(1)
Ag(1)-O(1)
Ag(1)-Ag(2)
Ag(3)-Ag(4)
Ag(1)-S(1)#1
Ag(3)-C(1)
Ag(2)-C(5)
Ag(1)-O(4)
2.555(6)
2.248(5)
C(1)-Au-S(1)
S(1)-Au-Ag(1)
174.1(2)
108.88(6)
Au-Ag(1)-S(1)#1
Au-S(1)-Ag(1)#1
88.01(5)
138.60(10)
C(1)-Au-S
174.84(17)
Ag(3)-Au-Ag(2) 143.726(18)
Ag(1)-Au-Ag(3) 114.358(18) Au-Ag(3)-Ag(4) 129.43(2)
Ag(1)-Au-Ag(2) 61.091(16)
a Symmetry transformations used to generate equivalent atoms: #1
-x+1, -y+1, -z+1; #2 x+1, y, z; #3 x-1, y, z; #4 -x+1, -y+1, -z.
a Symmetry transformations used to generate equivalent atoms: #1
-x+1, y+1/2, -z+1/2; #2 -x+1, y-1/2, -z+1/2.
for 5 (C29H35Ag4AuF12O8S3): C, 23.79; H, 2.41; S, 6.57. Found:
C, 23.69; H, 2.15; S, 7.19. FT-IR (Nujol mulls): ν(tht) at 1265
1.54 ppm (m, 4H, H2O). 19F NMR (282.4 MHz, CDCl3):
-73.5 ppm (s, 12F, CF3CO2). (ES-) m/z: 334 [Ag(CF3CO2)2]-,
662 [Ag2(CF3CO2)3(tht)(OH2)]-.
cm-1, ν(mes) at 893 cm-1, and ν(CF3CO2) at 1650 and 1211 cm-1
.
1H NMR (75.5 MHz, CDCl3):
δ 6.99 (s, 2H, m-H ),
3.22 (m, 12H, S-CH2-CH2-), 2.49 (s, 6H, o-Me), 2.31 (s, 3H,
p-Me), and 2.11 ppm (m, 12H, S-CH2-CH2-). 19F NMR (282.4
MHz, CDCl3): -73.6 ppm (s, 12F, CF3CO2). (ES-) m/z: 333
[Ag(CF3CO2)2]-, 554 [Ag2(CF3CO2)3]-.
Crystallography. The crystals were mounted in inert oil on glass
fibers and transferred to the cold gas stream of a Nonius Kappa
CCD diffractometer equipped with an Oxford Instruments low-
temperature attachment. Data were collected by monochromated
Mo KR radiation (λ ) 0.71073 Å). Scan type: ω and φ. Absorption
corrections: numerical (based on multiple scans). The structures
were solved by direct methods and refined on F2 using the program
SHELXL-97.14 All non-hydrogen atoms were anisotropically
refined, and hydrogen atoms were included using a mixed model.
Further details on the data collection and refinement methods can
be found in Table 1. Selected bond lengths and angles are shown
in Tables 2-6, and crystal structures of 1, 3, 4, 6, and 7 can be
seen in Figures 1-9. CCDC-606941-606945 contain the supple-
mentary crystallographic data for this paper. These data can be
obtained free of charge via www.ccdc.cam.ac.uk/conts/retrieving-
.html (or from the Cambridge Crystallographic Data Centre, 12
Union Rd., Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033;
or e-mail: deposit@ccdc.cam.ac.uk).
Synthesis of [AuAg4(mes)(CF3CF2CO2)4(tht)3]n (6). To a
solution of [Au(mes)] (0.063 g, 0.2 mmol) in 20 mL of dichlo-
romethane were added AgCF3CF2CO2 (0.217 g, 0.8 mmol) and tht
(0.054 mL, 0.6 mmol), and the mixture was stirred for 30 min.
The solution was then concentrated in a vacuum, and 20 mL of
hexane was added to precipitate complex 6 as a pale yellow solid
(0.376 g, 74.4%). Anal. Calcd for 6 (C33H35Ag4AuF20O8S3): C,
23.81; H, 2.12; S, 5.78. Found: C, 23.33; H, 2.10; S, 5.39. FT-IR
(Nujol mulls): ν(tht) at 1260 cm-1, ν(mes) at 891 cm-1, and ν(CF3-
CF2CO2) at 1649 and 1214 cm-1. H NMR (75.5 MHz, CDCl3):
1
δ 7.00 (s, 2H, m-H), 3.15 (m, 12H, S-CH2-CH2-), 2.46 (s, 6H,
o-Me), 2.31 (s, 3H, p-Me), and 2.10 ppm (m, 12H, S-CH2-CH2-
). 19F NMR (282.4 MHz, CDCl3): -83.2 (s, 8F, CF3CF2CO2) and
-118.9ppm(s,12F,CF3CF2CO2).(ES-)m/z: 433[Ag(CF3CF2CO2)2]-,
704 [Ag2(CF3CF2CO2)3]-.
Synthesis of {[AuAg4(mes)(CF3CO2)4(tht)(H2O)]‚H2O‚CH2Cl2}n
(7). Complex 3 (0.257 g, 0.2 mmol) was dissolved in 20 mL of
dichloromethane, and water (10 µL, 0.4 mmol) was added. The
solution, which rapidly turned orange, was stirred for 15 min,
and further evaporation of the solvent gave complex 7 as a dark
orange solid (0.106 g, 40.6%). Anal. Calcd for 7 (C22H25Ag4-
AuCl2F12O10S): C, 18.54; H, 1.77; S, 2.25. Found: C, 18.81; H
1.71; S, 2.38. FT-IR (Nujol mulls): ν(H2O) at 3429 cm-1, ν(tht)
at 1258 cm-1, ν(mes) at 846 cm-1, and ν(CF3CO2) at 1653 and
Acknowledgment. This work was supported by the DGI-
(MEC)/FEDER (CTQ2004-05495). R.C.P. thanks MEC for a
grant. M.M. thanks CAR for a grant.
Supporting Information Available: Figures S1-4 show the
packing of complexes 3, 4, 6, and 7 in the solid state. This material
can be obtained, free of charge, via the Internet at http://pubs.acs.org.
OM060413U
1
1184 cm-1. H NMR (75.5 MHz, CDCl3): δ 7.05 (s, 2H, m-H),
5.29 (s, 2H, CH2Cl2), 3.19 (m, 4H, S-CH2-CH2-), 2.47 (s, 6H,
o-Me), 2.35 (s, 3H, p-Me), 2.14 (m, 4H, S-CH2-CH2-), and
(14) Sheldrick, G. M. SHELXL-97; University of Go¨ttingen: Go¨ttingen,
Germany, 1997.