Synthesis and structural characterization of neutral silver(I) complexes with arenephosphinothiols. Crystal structures of [Ag4{2-(Ph2P)-6-(Me3Si)C6H 6S}4] and [Ag4{2-(Ph2PO)-6-(Me3Si)C6H 3S}4]

Article abstract of DOI:10.1021/ic9808403

Silver complexes of the anionic forms of 2-(diphenylphosphino)benzenethiol [2-(PH₂P)C₆H₄SH] (1), 2-(diphenylphosphino)-6-(trimethylsilyl)benzenethiol [2-(Ph₂P)-6-(Me₃Si)C₆H₃SH] (2), and 2-(diphenylphosphinyl)-6-(trimethylsilyl)benzenethiol [2-(Ph₂PO)-6-(Me₃Si)C₆H₃SH] (3) have been prepared by an electrochemical procedure and characterized by spectroscopic (IR, ¹H, ¹³C, and ³¹P NMR) methods, and ligand 3 and [Ag₄{2-(Ph₂P)-6-(Me₃Si)C₆H ₃S}₄] (5) and [Ag₄{2-(Ph₂PO)-6-(Me₃Si)C₆H ₃S}₄] (6) complexes were characterized by X-ray crystallographic techniques. Crystal data for 3: C₂₁H₂₃OPSSi, monoclinic, P2(1)/n, a = 11.3730(4) ?, b = 11.1562(4) ?,c= 17.1153(6) ?, β = 103.961(1)°, V = 2107.4(1) ?³, Z = 4, 2730 reflections with I_o > 2σ(I_o), R = 0.0621. Crystal data for 5: C₈₄H₈₈Ag₄P₄S₄Si ₄, tetragonal, P4(2)2(1)2, a = 18.8454(7) ?, b= 18.8454(7) ?, c = 24.596(2) ?, V = 8735.1(7) ?³, Z = 4, 4676 reflections with I_o > 2σ(I_o), R = 0.0286. Crystal data for 6: C₉₀H₉₇Ag₄N₃O₄P ₄S₄Si₄, trigonal, P1, a = 13.4567(1) ?, b= 14.4148(2) ?, c = 14.8080(2) ?, a = 99.130(1)°, β = 98.815(1)°, g = 114.211(1)°, V = 2509.38(5) ?³, Z = 1, 6345 reflections with I_o > 2σ(I_o), R = 0.0505. The [Ag₄{2-(Ph₂P)-6-(Me₃Si)C₆H ₃S}₄] (5) compound is tetranuclear with an array of four silver atoms bridged by four sulfur atoms. Each silver atom has a distorted trigonal [AgS₂P] environment with each ligand acting as P,S bidentate S-bridging ligand. The [Ag₄(2-(Ph₂PO)-6-(Me₃Si)C₆H ₃S}4] (6) complex is also tetranuclear, but in this case two of the silver atoms are [AgO₂S₂] tetracoordinated and the other two Ag atoms are [AgS₂] two coordinated.

Full text of DOI:10.1021/ic9808403

538
Inorg. Chem. 1999, 38, 538-544
Synthesis and Structural Characterization of Neutral Silver(I) Complexes with
Arenephosphinothiols. Crystal Structures of [Ag4{2-(Ph2P)-6-(Me3Si)C6H6S}4] and
[Ag4{2-(Ph2PO)-6-(Me3Si)C6H3S}4]
Paulo Perez-Lourido, Jose A. Garcia-Vazquez,* Jaime Romero,* and Antonio Sousa*
Departamento de Qu´ımica Inorga´nica, Universidad de Santiago, 15706 Santiago de Compostela, Spain
Eric Block
Department of Chemistry, State University of New York at Albany, Albany, New York 12222
Kevin P. Maresca and Jon Zubieta*
Department of Chemistry, Syracuse University, Syracuse, New York 13244
ReceiVed July 20, 1998
Silver complexes of the anionic forms of 2-(diphenylphosphino)benzenethiol [2-(Ph2P)C6H4SH] (1), 2-(diphe-
nylphosphino)-6-(trimethylsilyl)benzenethiol [2-(Ph2P)-6-(Me3Si)C6H3SH] (2), and 2-(diphenylphosphinyl)-6-
(trimethylsilyl)benzenethiol [2-(Ph2PO)-6-(Me3Si)C6H3SH] (3) have been prepared by an electrochemical procedure
1
and characterized by spectroscopic (IR, H, 13C, and 31P NMR) methods, and ligand 3 and [Ag4{2-(Ph2P)-6-
(Me3Si)C6H3S}4] (5) and [Ag4{2-(Ph2PO)-6-(Me3Si)C6H3S}4] (6) complexes were characterized by X-ray
crystallographic techniques. Crystal data for 3: C21H23OPSSi, monoclinic, P2(1)/n, a ) 11.3730(4) Å, b )
11.1562(4) Å, c ) 17.1153(6) Å, â ) 103.961(1)°, V ) 2107.4(1) Å3, Z ) 4, 2730 reflections with Io > 2σ(Io),
R ) 0.0621. Crystal data for 5: C84H88Ag4P4S4Si4, tetragonal, P4(2)2(1)2, a ) 18.8454(7) Å, b ) 18.8454(7) Å,
c ) 24.596(2) Å, V ) 8735.1(7) Å3, Z ) 4, 4676 reflections with Io > 2σ(Io), R ) 0.0286. Crystal data for 6:
C90H97Ag4N3O4P4S4Si4, trigonal, P1, a ) 13.4567(1) Å, b ) 14.4148(2) Å, c ) 14.8080(2) Å, R ) 99.130(1)°,
â ) 98.815(1)°, g ) 114.211(1)°, V ) 2509.38(5) Å3, Z ) 1, 6345 reflections with Io > 2σ(Io), R ) 0.0505. The
[Ag4{2-(Ph2P)-6-(Me3Si)C6H3S}4] (5) compound is tetranuclear with an array of four silver atoms bridged by
four sulfur atoms. Each silver atom has a distorted trigonal [AgS2P] environment with each ligand acting as P,S
bidentate S-bridging ligand. The [Ag4(2-(Ph2PO)-6-(Me3Si)C6H3S}4] (6) complex is also tetranuclear, but in this
case two of the silver atoms are [AgO2S2] tetracoordinated and the other two Ag atoms are [AgS2] two coordinated.
Introduction
heptanuclear cadmium complex,5 and the presence of three
bulkier tert-butyl groups in the ring allows the formation of
binuclear compounds [M(SC6H2tBu3-2,4,6)2]2 (M ) Zn6 or Cd7).
A similar situation is found in the silver chemistry. In the case
of a relatively unencumbered ligand such as (Me3Si)CH2S-, the
compound is polymeric, while with the more hindered ligand
(Me3Si)2CHS-, the compound is octanuclear, and the bulkier
ligands (Me3Si)3CS and (Me2PhSi)2CS- allow the formation
of tetra- and trinuclear complexes, respectively.8 (b) Auxiliary
or coligands may be introduced to block some of the coordina-
tion sites around the metal. An example is the monomeric
complex [Zn(SC6H2tBu3-2,4,6)2(NC5H3-2,6-Me2)].9 (c) Other
It is well-known that metal thiolate complexes adopt geom-
etries of variable nuclearities and great structural complexity.
These features are the result of the tendency of thiolate ligands
to bridge metal centers to yield oligomeric or polymeric
species.1-3 These aggregation phenomena may be limited by a
number of expedients. (a) Steric constraints may be introduced
by appropriate ligand design, for example, using bulky groups
close to the sulfur atom that might modify the degree of
aggregation as a result of steric hindrance. Thus, for example,
the crystal structure of [M(SPh)2] (M ) Zn or Cd),4 with SPh-
ligands, which may be regarded as prototypes for sterically less
hindered ligands, are polynuclear. However, the presence of a
methyl group in the ortho position on the phenyl ring gives a
(5) Dance, I. G.; Garbutt, R. G.; Scudder, M. L. Inorg. Chem. 1990, 29,
1571.
(6) Bochmann, M.; Webb, K.; Harman, M.; Hursthouse, M. B. Angew.
Chem., Int. Ed. Engl. 1990, 29, 638.
(7) Bochmann, M.; Bwembya, G.; Grinter, R.; Lu, J.; Webb, K.;
Willianson, D.; Hurthouse, M. B.; Mazid, M. Inorg. Chem. 1993, 32,
532.
(8) Tang, K.; Aslam, M.; Block, E.; Nicholson, T.; Zubieta, J. Inorg. Chem.
1987, 26, 1488.
(9) Bochmann, M.; Bwembya, G. C.; Grinter, R.; Powell, A. K.; Webb,
K. J.; Hursthouse, M. B.; Malik, K. M. A.; Mazid, M. A. Inorg. Chem.
1994, 33, 2290.
* To whom correspondence should be addressed.
(1) (a) Raper, E. S. Coord. Chem ReV. 1985, 61, 115. (b) Ibid. 1996,
153, 199. (c) Ibid. 1997, 165, 475.
(2) Krebs, B.; Henkel, G. Angew. Chem., Int. Ed. Engl. 1991, 30, 769.
(3) (a) Dance, I. G. Polyhedron 1986, 5, 1037. (b) Blower, P. G.; Dilworth,
J. R. Coord. Chem. ReV. 1987, 76, 121. (c) Dilworth, J. R.; Hu, J.
AdV. Inorg. Chem. 1993, 40, 411.
(4) Dance, I. G.; Garbutt, R. G.; Craig, D. C.; Scudder, M. L. Inorg. Chem.
1987, 26, 4057.
10.1021/ic9808403 CCC: $18.00 © 1999 American Chemical Society
Published on Web 01/20/1999

Neutral Silver(I) Complexes with Arenephosphinothiols
Inorganic Chemistry, Vol. 38, No. 3, 1999 539
mass spectrometer connected to a DS90 data system, using 3-nitrobenzyl
alcohol (3-NOBA) as a matrix material.
strategies include the incorporation of additional donor atoms
in chelating thiolate ligands and (d) the simultaneous exploitation
of two or more of these conditions. Thus, the presence of
additional donor atoms, such as the N atom in pyridine-2-thione
(Hpyt) and pyrimidine-2-thione (Hpymt) and also the introduc-
tion of bulky substituents in the ligand modify the nuclearity
of the complexes; thus, the cadmium complex with pyridine-
2-thione, [Cd(pyt)2],10 is polymeric, while the greater steric
constraints introduced by the methyl groups of 4,6-dimethypy-
rimidine-2-thione prevents polymerization and [Cd(dmpymt)2]11
is hexanuclear. When a more voluminous substituent such as
the trimethylsilyl group is introduced, the cadmium complex
with 3-(trimethylsilyl)pyridine-2-thione is dinuclear.12 On the
other hand, the presence of coligands, such as 2,2′-bipyridine,
1,10-phenanthroline, bis(diphenylphosphino)methane, or 1,2-
bis(diphenylphosphine)ethane), might modify such aggregation
processes producing mono- or binuclear thiolate complexes.13
As a part of our continuing interest in the chemistry of
sterically hindered thiolates,14 and as a consequence of the
paucity of known structures of neutral homoleptic species of
the type [Ag(SR)]n,8,15 we report in this paper the electrochemi-
cal synthesis and characterization of a series of complexes of
silver(I) with 2-(diphenylphosphino)benzenethiol [2-(Ph2P)C6H4-
SH], 2-(diphenylphosphino)-6-(trimethylsilyl)benzenethiol [2-
(Ph2P)-6-(Me3Si)C6H3SH] and 2-(diphenylphosphine oxide)-6-
(trimethylsilyl)benzenethiol [2-(Ph2PO)-6-(Me3Si)C6H3SH] ligands
which have, in addition to the thiolate sulfur atom, other donor
atoms such as phosphorus or oxygen in the same ligand. In
addition, some of these ligands also possess a bulky trimeth-
ylsilyl group close to the sulfur atom which might modify the
degree of aggregation of the thiolate complexes.
Preparation of the Ligands. All manipulations were carried out
under argon, using high vacuum and conventional Schlenk techniques.
Solvents used to isolate the products were distilled over appropriate
drying agents and degassed and saturated with argon by passing argon
through them during 1 h. The reactants and products were kept away
from light by covering the flasks with aluminum foil to suppress
photoinitiated decomposition.
Synthesis of 2-(Diphenylphosphino)benzenethiol (1). The white
crystalline solid was prepared from thiophenol (7 g, 63.5 mmol), with
TMEDA (22 mL, 142.0 mmol), n-butyllithium (2.5 M in hexane, 57
mL, 142.0 mmol), and diphenylphosphine chloride (10 g, 45.5 mmol)
equivalent to 5 g (71%) of thiophenol by the procedure of Block et
al.16 The crude product was evaporated to dryness and extracted with
diethyl ether. The ether layer was washed with water to remove the
acid produced and dried (MgSO4), and the solvents were removed in
vacuo to yield 8.7 g (65%, 29.6 mmol) of crude product. The crude
product was purified by dissolution in diethyl ether, adding activated
charcoal, concentrating in vacuo, and adding hexane to help precipitate
the phosphinethiol.
Recrystallization was also accomplished from ether/hexane solution.
An analytically pure sample was obtained by chromatographing the
crude product with a Chromatotron (4 mm silica plates, hexane/CH2-
Cl2). The isolated phosphinethiol was a colorless solid, mp 98-99 °C.
Anal. Calcd for C18H15PS: C, 73.34; H, 5.20; S, 10.88. Found: C,
73.45; H, 5.14; S, 10.67. 1H NMR (CDCl3): δ 7.5-6.7 (m, 14H,
phenyl), 4.1 (d, J (31P-1H) ) 2.2 Hz), 1H, SH). 13C NMR (CDCl3):
2
1
δ 137.7 (d, J (31P-13C) ) 30.3 Hz, (C1)), 135.8 (d, J (31P-13C) )
7.9 Hz, (C2)), 130.4 (d, J (31P-13C) ) 3.1 Hz, (C3)), 125.9 (C4),
2
l29.2 (C5), 134.0 (C6), 135.3 (d, 1J (31P-13C) ) 9 Hz, (C7)), l33.7 (d,
2J (31P-13C) ) 2.8 Hz, (C8)), 128.6 (d, J (31P-13C) ) 7 Hz, (C9)),
3
129.0 (C10). 31P NMR (CDCl3): δ -14.51 (relative to external 85%
H3PO4).
Synthesis of 2-(Diphenylphosphino)-6-(trimethylsilyl)benzenethiol
(2). The white solid was prepared from 2-(trimethylsilyl)benzenethiol
(9.82 g, 0.054 mol) obtained by the method of Martin and Figuly,17
with TMEDA (6.5 g, 0.054 mol), n-butyllithium (44 mL, 2.5 M hexane
solution, 0.11 mol), and diphenylphosphine chloride (9.67 g, 0.044 mol)
following the procedure of Block.17 The reaction product was quenched
with concentrated HCl at 0 °C. The mixture was concentrated in vacuo
and dissolved in degassed diethyl ether. Residual acid in the organic
layer was removed with degassed water. The solution was dried
(MgSO4) and concentrated in vacuo to give 15 g of crude product (93%,
0.041 mol). Yield after recrystallization from hexane/CH2Cl2 solution
was 67% (10.86 g, 0.03 mol). Analytically pure sample was obtained
by chromatography on a Chromatotron (hexane/CH2Cl2); mp 102-
103 °C. Anal. Calcd for C21H23PSSi: C, 68.82; H, 6.33; S, 8.74.
Found: C, 69.00; H, 6.43; S, 8.67. 1H NMR (CDCl3): δ 7.6-6.7 (m,
Experimental Section
Silver (Ega Chemie) was used as plates (ca. 2 × 2 cm). All other
reagents, including acetonitrile, thiophenol, TMEDA (tetramethyleth-
ylenediamine), n-butyllithium, chlorodiphenylphosphine, and diphe-
nylphosphinic chloride were commercial products (Aldrich) and were
used as supplied.
Microanalysis were performed using a Carlo-Erba EA microanalyzer.
IR spectra were recorded as KBr disks with a Bruker IF5 66v
spectrophotometer. 1H and 13C NMR spectra were recorded on a
Brucker WN 300 MHz instrument using CDCl3 as solvent; chemical
shifts were determined against TMS as internal standard. 31P NMR
was recorded on a Brucker AC 500 spectrometer using 85% H3PO4 as
internal standard. FAB data were recorded on a KRATOS MS 50TC
4
13H, phenyl), 4.6 (d, 1H, J (31P-1H) ) 11.24 Hz, SH), 0.38 (s, 9H,
(10) Hursthouse, M. B.; Khan, O. F.; Mazid, M.; Motevalli, M.; O’Brien,
P. Polyhedron 1990, 9, 541.
Si(CH3)3). 13C NMR (CDCl3): δ 143.7 (d, J (31P-13C) ) 29.9 Hz,
(C)), 141.4 (C), 137.2 (d, J (31P-13C) ) 6.2 Hz, (C)), 135.8 (C), 135.6
(CH), 134.7 (CH), 134.0 (d, J (331P-13C) ) 19.2 Hz, (CH)), 128.8 (d,
J (31P-13C) ) 26.5 Hz, (CH)), 128.7 (C), 125.5 (CH), 0.10 (Si(CH3)3).
31P NMR (CDCl3): δ -15.02 (relative to external 85% H3PO4).
Synthesis of 2-(Diphenylphosphinyl)-6-(trimethylsilyl)benzene-
thiol (3). The white solid was prepared from 2-(trimethylsilyl)-
benzenethiol (7.23 g, 0.04 mol), with TMEDA (4.62 g, 0.04 mol),
n-butyllithium (34 mL, 2.5 M hexane solution, 0.085 mol), and
diphenylphosphinic chloride (4.54 g, 0.02 mol) following the same
method as in the synthesis of 2. The reaction mixture was quenched
with concentrated HCl at 0 °C, and the solvent was evaporated. The
residue was extracted into diethyl ether, and excess acid was removed
with water. The organic layer was dried (MgSO4), and solvents were
removed in vacuo. The residue was washed with ether/hexane 1:9, and
the white crystalline product dried in vacuo. An analytically pure sample
(11) Castro, R.; Garc´ıa-Va´zquez, J. A.; Romero, J.; Sousa, A.; Pritchard,
R.; McAuliffe, C. A. J. Chem. Soc., Dalton Trans. 1994, 1115.
(12) Castro, R.; Garc´ıa-Va´zquez, J. A.; Romero, J.; Sousa, A.; Castin˜eiras,
A.; Hiller, W.; Stra¨hle, J. Inorg. Chim. Acta 1993, 211, 47.
(13) (a) Castro, R.; Dura´n, M. L.; Garc´ıa-Va´zquez, J. A.; Romero, J.; Sousa,
A.; Castin˜eiras, A.; Hiller, W. Stra¨hle, J. Z. Naturforsch. 1990, 45b,
1632. (b) J. Chem. Soc., Dalton Trans. 1990, 531. (c) Dura´n, M. L.;
Romero, J.; Garc´ıa-Va´zquez, J. A.; Castro, R.; Castin˜eiras, A.; Sousa,
A. Polyhedron 1991, 10, 197. (d) Castro, R.; 4 Dura´n, M. L.; Garc´ıa-
Va´zquez, J. A.; Romero, J.; Sousa, A.; Castin˜eiras, A.; Hiller, W.;
Stra¨hle, J. Z. Naturforsch. 1992, 47b, 1067. (e) Castro, R.; Garc´ıa-
Va´zquez, J. A.; Romero, J.; Sousa, A.; McAuliffe, C. A.; Pritchard,
R. Polyhedron 1993, 12, 2241. (f) Castro, R.; Garc´ıa-Va´zquez, J. A.;
Romero, J.; Sousa, A.; Hiller, W.; Stra¨hle, J. Polyhedron 1994, 13,
273. (g) Castro, J. A.; Romero, J.; Garc´ıa-Va´zquez, J. A.; CastiOÅ eiras,
A.; Sousa, A.; Zubieta, J. Polyhedron 1995, 14, 2841.
(14) (a) Castro, R.; Garc´ıa-Va´zquez, J. A.; Romero, J.; Sousa, A.;
Castin˜eiras, A.; Hiller, W.; Stra¨hle, J. Inorg. Chim. Acta 1993, 211,
47. (b) Tallon, J.; Garc´ıa-Va´zquez, J. A.; Romero, J.; Louro, M. S.;
Sousa, A.; Chen, Q.; Chang, Y.; Zubieta, J. Polyhedron 1995, 14,
2309.
(16) Block, E.; Ofori-Okai, G.; Zubieta, J. J. Am. Chem. Soc. 1989, 111,
2327.
(15) Block, E.; Macherone, D.; Shaikh, S. N.; Zubieta, J. Polyhedron 1990,
9, 1429.
(17) Figuly, G. D.; Loop, C. K.; Martin, J. C. J. Am. Chem. Soc. 1989,
111, 654.

540 Inorganic Chemistry, Vol. 38, No. 3, 1999
Perez-Lourido et al.
was obtained after chromatografing the crude product using degassed
hexane/CH2Cl2 mixtures. Crystals suitable for X-ray difffraction were
isolated by crystallizing the eluted solution. Yield 4.5 g (59%, 0.012
mol), mp 194-195 °C. Anal. Calcd for C21H23OPSSi: C, 65.94; H,
temperature. The hkl range was -9 < h <15, -14 < k <14, -22 <
l <21 for 3, -16 < h <25, -23 < k <25, -32 < l <32 for 5, and
-17 < h <11, -18 < k <19, -14 < l <19 for 6. 7954 reflections
were collected for 3 in the range θ ) 1.95-22.49°, 31422 reflections
for 5 in the range θ ) 1.36-21.00°, and 10321 in the range θ ) 1.44-
22.50° for (6).
1
6.06; S, 8.38. Found: C, 69.00; H, 6.43; S, 8.35. H NMR (CDCl3):
δ 7.8-6.8 (m, 13H, phenyl), 7.08 (s, 1H, SH), 0.21 (s, 9H, Si(CH3)3).
13C NMR (CDCl3): δ 146.4 (d, J (31P-13C) ) 7.1 Hz, (CS)), 142.4 (d,
J (31P-13C) ) 5.9 Hz, (CSi)), 138.3 (d, J (31P-13C) ) 1.9 Hz, (CH)),
135.1 (d, J (31P-13C) ) 14.5 Hz, (CH)), 132.1 (d, J (31P-13C) ) 2.0
Hz, (CH)), 132.1 (d, J (31P-13C) ) 8.3 Hz, (CH)), 131.7 (d, J (31P-
13C) ) 106.0 Hz, (CP)), 128.6 (d, J (31P-13C) ) 104.8 Hz, (CP)),
128.5 (d, J (31P-13C) ) 12.0 Hz, (CH)), 123.5 (d, J (31P-13C) ) 12.0
Hz, (CH)), -0.11 (Si(CH3)3). 31P NMR (CDCl3): δ 34.1 (relative to
external 85% H3PO4).
Electrochemical Synthesis of the Complexes. The electrochemical
method used in the synthesis of the metal complexes is similar to that
described by Tuck.18 An acetonitrile (50 mL) solution of the corre-
sponding thiolato ligand and a small amount of tetramethylammonium
perchlorate (ca. 10 mg) as the supporting electrolyte was electrolyzed
using a silver sacrificial anode and a platinum cathode. In all cases,
hydrogen evolved at the cathode. These cells can be summarized as:
Structure Solution and Refinement. For these compounds, full
matrix least-squares calculations were carried out on F2. Refinements
were carried out using 2730 reflections for 3, 4676 reflections for 5,
and 6345 reflections for 6 with F > 2.0σ(Fo). For compound 3 the
final cycle of full-matrix least-squares based on 226 variable parameters
converged to R ) ∑(|Fo| - |Fc|)/(Fo) ) 0.0621 and Rw ) [(∑w(|Fo|
- |Fc|)2]1/2 ) 0.1366. The maximum and minimum peaks on the final
difference Fourier map were 0.263 and -0.221 eÅ-3. For compound 5
the final cycle of full-matrix least-squares based on 379 variable
parameters converged to R ) ∑(|Fo| - |Fc|)/(Fo) ) 0.0286 and Rw )
[(∑w(|Fo| - |Fc|)2]1/2 ) 0.0530. The maximum and minimum peaks
on the final difference Fourier map were 0.199 and -0.170 eÅ-3. For
compound 6 the final cycle of full-matrix least-squares based on 505
parameters converged to R ) ∑(|Fo| - |Fc|)/(Fo) ) 0.0505 and Rw )
[(∑w(|Fo| - |Fc|)2]1/2 ) 0.1337. The maximum and minimum peaks
on the final difference Fourier map were 1.034 and -0.395 eÅ-3
.
Pt(-)/CH3CN + RP-SH/M(+)
.
Atomic scattering factors were taken from International Tables for X-ray
Crystallography.19 Crystallographic data and final R indices for all three
compounds are given in Table 1. Significant bond distances and angles
for 3, 5, and 6 are given in Tables 2, 3, and 4, respectively. Complete
crystallographic details are given in the Supporting Information. ORTEP
diagrams of the molecules are shown in Figures 1, 2, and 4.
Preparation of [Ag{2-(Ph2P)C6H4S}] (4). Electrolysis of an ac-
etonitrile solution (50 mL) containing 2-(diphenylphosphino)ben-
zenethiol (1) (0.220 g, 0.75 mmol) at 12 V and 20 mA for 1 h dissolved
85 mg of metal (Ef ) 1.05 mol F-1). As the reaction proceeded, a
solid was formed immediately at the anode, and hydrogen evolved at
the cathode. At the end of the experiment the solid obtained was filtered,
washed with cool acetonitrile and ether, and dried under vacuum, 0.26
g (85%). This solid was identified as [Ag{2-(Ph2P)C6H4S}] (4). Anal.
Calcd for C18H14AgPS: C, 53.88; H, 3.32; S, 7.98. Found: C, 53.31;
H, 3.49; S, 7.54. IR (KBr, cm-1): 1570 (m), 1437 (s), 1417 (m), 1249
(m), 1095 (s), 1037 (m), 997 (w), 744 (s), 729 (w), 694 (s), 506 (m).
1H NMR (CDCl3): δ 7.8-6.0 (m, 14H). 31P NMR (CDCl3): δ 32.42
(s).
Results and Discussion
The synthesis of homoleptic silver(I) phosphino- and phos-
phinylthiolate complexes [Ag(RP-S)] can be readily ac-
complished in good yield by the electrochemical method
described, a methodology similar to previous work on related
systems.20-23
The electrochemical efficiency, defined as moles of metal
dissolved per Faraday of charge, was found to have an average
value of 1.0 ( 0.05 mol F-1. These results, together with the
evolution of hydrogen at the cathode, are compatible with the
occurrence of the following electrode reactions
Preparation of [Ag4{2-(Ph2P)-6-(Me3Si)C6H3S}4] (5). Electro-
chemical oxidation of a silver anode in a solution of 2-(diphenylphos-
phino)-6-(trimethylsilyl)benzenethiol (2) (0.273 g, 0.75 mmol) in
acetonitrile (50 mL) at 18 V and 10 mA for 2 h caused 82 mg of Ag
to dissolve (Ef ) 1.02 mol F-1). During the electrolysis, hydrogen was
evolved at the cathode, and after 1 h, white needles appeared on the
electrodes and at the bottom of the vessel. The solid was filtered, washed
with acetonitrile and ether, and dried under vacuum, 0.31 g (88%).
This compound was identified as [Ag{2-(Ph2P)-6-(Me3Si)C6H3S}] (5).
Anal. Calcd for C21H22AgPSSi: C, 53.29; H, 4.86; S, 6.77. Found: C,
53.11; H, 4.89; S, 6.45. IR (KBr, cm-1): 1552 (m), 1479 (m), 1435
(m), 1349 (s), 1241 (m), 1095 (s), 998 (w), 852 (s), 837 (s), 743 (s),
cathode: RP-SH + e- f 1/2H2 + RP-S-
anode: RP-S- + Ag f [Ag(RP-S)] + e-
where RP-SH stands for the neutral ligand.
1
720 (w), 693 (m), 501 (m). H NMR (CDCl3): δ 7.8-6.3 (m, 22H),
[Ag{2-(Ph2P)C6H4S}] (4) was obtained as a white insoluble
solid which precipitated after several minutes of electrolysis.
The IR spectrum of the complex shows that the free ligand band
ν(S-H) at 2400-2500 cm-1 is absent, indicating that depro-
tonation of this group occurred and that it is coordinated as an
anionic ligand. Moreover, the spectrum also shows bands at
1600-1580 cm-1 assigned to ν(CdC) of the aromatic ring and
at 1000 cm-1 and 720-730 cm-1 attributed to ν(P-C) and ν-
(C-S), respectively. The room temperature 1H NMR spectrum
shows signals in the range 7.8-6.0 ppm due to the phenyl
protons and also the disappearance of the signal attributable to
0.46 (s, 9H). 31P NMR (CDCl3): δ 34.11. Recrystallization by diffusion
of MeOH into a solution of the compound in CHCl3 produces crystals
of [Ag{2-(Ph2P)-6-(Me3Si)C6H3S}] (5) suitable for X-ray studies.
Preparation of [Ag4{2-(Ph2PO)-6-(Me3Si)C6H3S}4] (6). A solution
of acetonitrile (50 mL) containing 2-(diphenylphosphinyl)-6-(trimeth-
ylsilyl)benzenethiol (3) (0.214 g, 0.56 mmol) was electrolyzed at 11
V and 10 mA during 1.5 h, and 61 mg of silver metal was dissolved
from the anode (Ef ) 1.00 mol F-1). The white microcrystalline
precipitate formed was filtered, and crystals suitable for X-ray diffrac-
tion studies were isolated from the filtrate, left to concentrate by
evaporation at room temperature, and identified as [Ag4{2-(Ph2PO)-
6-(Me3Si)C6H3S}4]0.3CH3CN (6), 0.225 g (88%). Anal. Calcd for
C90H97Ag4N3O4P4S4Si4: C, 52.05; H, 4.72; N, 2.02; S, 6.16. Found:
C, 51.45; H, 4.58; N, 1.98; S, 6.50. IR (KBr, cm-1): 1555 (m), 1483
(m), 1436 (m), 1352 (s), 1243 (s), 1172 (s), 1116 (m), 1040 (m), 998
(19) Cromer, D. T.; Waber, J. T. International Tables for X-ray Crystal-
lography; The Kynoch Press: Birmingham, England, 1974; Vol. IV,
Table 2.2A.
(20) Castro, R.; Dura´n, M. L.; Garc´ıa-Va´zquez, J. A.; Romero, J.; Sousa,
A.; Castellano, E. E.; Zukerman-Schpector, J. J. Chem. Soc., Dalton
Trans. 1992, 2559.
(21) Castro, J. A.; Romero, J.; Garc´ıa-Va´zquez, J. A.; Sousa, A.; Zubieta,
J.; Chang, Y. Polyhedron 1996, 15, 2741.
(22) PEÅ rez-Lourido, P.; Garc´ıa-Va´zquez, J. A.; Romero, J.; Louro, M. L.;
Sousa, A.; Zubieta, J. Inorg. Chim. Acta 1998, 271, 1.
(23) Garc´ıa-Va´zquez, J. A.; Romero, J.; Castro, R.; Sousa, A.; Rose, D.
J.; Zubieta, J. Inorg. Chim. Acta 1997, 260, 221.
1
(w), 851 (s), 748 (s), 727 (w), 694 (s), 625 (m), 556 (s). H NMR
(CDCl3): δ 7.8-6.7 (m, 22H), 0.5 (s, 9H). 31P NMR (CDCl3): δ 35.12.
X-ray Crystallography of 3, 5, and 6. Crystals of 3, 5, and 6 were
mounted on a glass fiber, and data were recorded on a CAD4
diffractometer with graphite monochromated Mo-KR radiation at room
(18) Habeeb, J. J.; Tuck, D. G.; Walters, F. H. J. Coord. Chem. 1978, 8,
27.

Neutral Silver(I) Complexes with Arenephosphinothiols
Inorganic Chemistry, Vol. 38, No. 3, 1999 541
Table 1. Crystal Data and Structure Refinement for 3, 5, and 6
3
5
6
empirical formula
formula weight
crystal size (mm)
temperature (K)
wavelength (Å)
crystal system
space group
unit cell dimensions
a, Å
C21H23POSSi4
382.51
C84H88Ag4P4S4Si4
1893.50
C90H97Ag4N3O4P4S4Si4
2080.67
0.40 × 0.40 × 0.40
0.10 × 0.10 × 0.10
0.10 × 0.10 × 0.10
298(2)
298(2)
298(2)
0.71073
monoclinic
P2(1)/n
0.71073
tetragonal
P4(2)2(1)2
0.71073
triclinic
P1
11.3730(4)
11.1562(4)
17.1153(6)
18.8454(7)
18.8454(7)
24.596(2)
13.4567(1)
14.4148(2)
14.8080(2)
99.130(1)
98.815(1)
114.211(1)
2509.38(5)
1
b, Å
c, Å
R, deg
â, deg
103.961(1)
γ, deg
volume, Å3
2107.4(1)
4
1.206
2.92
8735.1(7)
4
1.440
11.48
Z
density (calcd), mg/m3
absorption coefficient, cm-1
final R indices [I > 2σ(I)]
R1
1.377
10.10
0.0621
0.1366
0.0286
0.0530
0.0505
0.1337
wR2
wR2 ) {∑[w(Fo2 - Fc2)]/∑[w(Fo )2]}1/2
2
R1 ) ∑||Fo| - |Fc||/∑|Fo|
SH which in the free ligand appears at 4.1 ppm. On the other
hand, the 31P NMR spectrum shows a signal at 32.42 ppm,
which has shifted downfield from its position in the free ligand
spectrum, -14.51 ppm. This fact is taken as proof of coordina-
tion of the phosphorus atom. In the FAB mass spectrum of 4,
the largest m/z peak, 910, corresponds to [Ag3{2-(Ph2P)-
C6H4S}2]+. The spectrum also shows the peaks associated with
[Ag2{2-(Ph2P)C6H4S}]+ and [2-(Ph2P)C6H4S]+ at m/z 509 and
m/z 294, respectively. The peak clusters have the appropriate
isotope distribution. Elemental analysis is consistent with this
formulation, but the structure is not apparent from spectroscopy
data. Attempts to obtain crystals suitable for X-ray studies were
unsuccessful. Most likely, the compound is polymeric or as least
tetrameric with a structure similar to that found for 5 and 6
(vide infra).
Figure 1. Molecular structure of [2-(Ph2PO)-6-(Me3Si)C6H3SH] (3).
Table 2. Selected Bond Lengths (Å) and Angles (deg) for 3
Compounds 5 and 6 are obtained by oxidation of a silver
anode as white crystalline solids formed slowly at the bottom
of the cell as the reactions proceeded. The presence of
trimethylsilyl groups on the ligands increases their solubility
in the reaction medium. The IR spectra of these complexes are
similar to that of 4 with the addition of a strong band at 850
cm-1 characteristic of the rocking mode of the SiMe3 group
S-C(11)
P-C(36)
P-C(16)
Si-C(17)
Si-C(12)
1.784(4)
1.813(4)
1.829(4)
1.880(6)
1.913(4)
P-O
1.493(3)
1.821(4)
1.874(6)
1.883(5)
P-C(26)
Si-C(18)
Si-C(19)
O-P-C(36)
112.6(2)
106.7(2)
106.4(2)
112.9(3)
108.4(3)
108.9(2)
O-P-C(26)
O-P-C(16)
C(26)-P-C(16)
C(18)-Si-C(19)
C(18)-Si-C(12)
C(19)-Si-C(12)
110.1(2)
113.1(2)
107.7(2)
108.2(3)
110.7(2)
107.6(2)
C(36)-P-C(26)
C(36)-P-C(16)
C(18)-Si-C(17)
C(17)-Si-C(19)
C(17)-Si-C(12)
1
and a band in 6 at 1172 cm-1 assignable to ν(P-O). The H
NMR spectra show signals of the aromatic protons and also a
signal ca. 0.4 ppm assignable to the trimethylsilyl group. The
31P NMR spectra show only signals at 34.1 and 35.1 ppm for
5 and 6, respectively. FAB mass spectra of these complexes
show the molecular peaks for [Ag3(RP-S)2]+ at m/z 1052, 1086,
[Ag2(RP-S)]+ at m/z 589, 598, and [Ag(RP-S)]+ at m/z 473
and 498, respectively, for both compounds.
Description of the Structures. The structure of the ligand
2-(Ph2PO)6-(Me3Si)C6H3SH (3) is illustrated in Figure 1, and
the relevant metrical parameters are summarized in Table 2.
The bond angles and lengths (Table 2) in the rings are
essentially identical to those found in other (phenyl)PdO and
are unremarkable. The geometry around the central P atom is
slightly distorted tetrahedral, being bound to one oxygen atom
and one carbon atom of each one of the three phenyl rings.
The O-P-C angles, 110.1(2)-113.1(1)°, are slightly greater
that the corresponding C-P-C angles, 106.4(2)-107.7(2)°, but
they are in the range found in similar ligands, 111.6-114.5°
for O-P-C and 103.4-108.8° for C-P-C angles.24 The P-O
distance, 1.493(3) Å, is similar to those found in other OdPR3
ligands,24,25 1.475-1.498 Å, and they are in agreement the value
proposed for a PdO bond.26 The C-P distances, 1.813(4)-
1.829(4) Å, are also comparable with the above ligands (1.780-
(24) (a) Bernardinelli, G.; Gerdil, R. Cryst. Struct. Commun. 1979, 8, 921.
(b) Antipin, M. Yu.; Struchkov, Yu. T.; Mastrosov, E. Y.; Bondareko,
N. A.; Tsvetkov, E. N.; Kabachnik, M. Y. Zh. Strukt. Khim. 1981,
22, 100. (c) Tkachev, V. V.; Atovmyan, L. O.; Goncharova, L. V.;
Shvets, A. A.; Osipov, O. A. Zh. Strukt. Khim. 1982, 23, 168. (d)
Szlyk, E.; Zhang, Z.-Y.; Palenix, G. J.; Palenix, R. C.; Colgate, S. O.
Acta Crystallogr. 1989, 45C, 1234.
(25) (a) Orama, O.; Karku, M.; Na¨saa¨kka¨la¨, M.; Sundberg, M.; Uggla, R.
Cryst. Struct. Commun. 1979, 8, 409. (b). Churchill, M. R.; See, R.
F.; Randall, S. L.; 0Atwood, J. D. Acta Crystallogr. 1993, 49C, 345.
(c) Orama, O.; Koskinen, J. T. Acta Crystallogr. 1994, 50C, 608.
(26) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen, A.
G.; Taylor, R. J. Chem. Soc., Perkin Trans. 2, 1987, S1.

542 Inorganic Chemistry, Vol. 38, No. 3, 1999
Perez-Lourido et al.
consisting of a highly distorted tetrahedron of four silver atoms
bridged by the sulfur atoms of four thiolate anions. The distances
between silver atoms are in the range 2.93 to 3.52 Å, showing
that no significant silver-silver interactions exist in the
compound. Each silver atom is coordinated to one phosphorus
atom and the bridging sulfur atom of two thiolate ligands.
Therefore, each ligand acts as a η2(P-µ2-S) six-electron donor
ligand. Each silver atom is in a distorted trigonal-planar
environment [AgPS2], with a deviation of the Ag atom from
the best least squares donor atom plane of 0.327 (2) Å for Ag(2)
and 0.237 (2) Å for Ag(1). The bond angles between silver and
the atoms of the chelate rings are significantly smaller than the
idealized limit of 120°, (82.52(5)°, and 79.90(5)°), whereas the
angles involving donor atoms of different ligands have values
larger than 120°, 145.23(5)-145.19(5) for PAgS and 128.94(4)-
128.57(5)° for SAgS. These large deviations from the theoretical
values give rise to a highly distorted three-coordinate geometry.
The Ag(1)-S(2) and Ag(2)-S(1′) distances, 3.293(5) and
3.337(6) Å, are considerably longer that the other Ag-S
distances observed in this complex and even greater than the
sum of the van der Waals radii of the silver and sulfur atoms,27
indicating that the S(2) and S(1′) are not coordinated to the Ag-
(1) and Ag(2) sites, respectively.
Figure 2. An ORTEP view of the structure of [Ag4{2-(Ph2P)-6-(Me3-
Si)C6H3S}4] (5).
The silver atoms are linked through asymmetric sulfur
bridges, as the Ag-S distances are significantly different. Thus,
the Ag-S bond distances are of two types: the shorter bonds
have values of 2.448(2) and 2.4481(14) Å, and the longer have
distances of 2.6289(14) and 2.6435(14) Å. The latter distances
correspond to the Ag-S bonds of the chelate rings. The shorter
set of bond lengths is close to those found in other silver(I)
complexes with heterocyclic thiones involving sulfur atom
bridges and a trigonal environment around silver atoms.28
However, the longer Ag-S bond lengths of 5 are greater that
those found in the above-cited tricoordinated silver(I) com-
pounds. The steric strain in the five-member chelate rings and
the small “bite” of the ligand appear to be primarily responsible
for the lengthening of the metal-sulfur bonds. The Ag-P bond
distances, 2.4282(14) and 2.426(2) Å, are similar to those found
in other three-coordinated silver(I) complexes, 2.390-2.524 Å.29
Each of the phenyl rings is planar, but the sulfur and
phosphorus atoms lie out of the plane of the phenyl ring to which
they are bound (by 0.0216 and 0.0407 Å for P(1) and S(1),
respectively, and 0.0844 and 0.2130 Å for S(2) and P(2),
respectively).The interplanar angle between the phenyl ring of
ligands that are bonded to adjacent silver have values of ca.
84°.
Figure 3. Perspective view of the coordination spheres of the metals
in [Ag4{2-(Ph2P)-6-(Me3Si)C6H3S}4] (5).
Table 3. Selected Lengths (Å) and Angles (deg) for 5
Ag(1)-P(1)
Ag(1)-S(1)
Ag(1)-Ag(2)a
Ag(2)-S(1)
P(1)-C(26)
P(2)-C(46)
P(2)-C(56)
S(2)-C(41)
2.4282(14)
2.6289(14)
2.9694(6)
2.448(2)
1.822(3)
1.815(3)
1.821(3)
1.781(3)
Ag(1)-S(2)a
Ag(1)-Ag(2)
Ag(2)-P(2)
Ag(2)-S(2)
P(1)-C(36)
P(1)-C(16)
P(2)-C(66)
S(1)-C(11)
2.4481(14)
2.9356(6)
2.426(2)
2.6435(14)
1.808(3)
1.840(3)
1.813(3)
1.786(3)
The molecular structure of [Ag4{2-(Ph2PO)-6-(Me3Si)-
C6H3S}4] (6) is shown in Figure 4, together with the atomic
numbering scheme adopted. For clarity, a view of the coordina-
tion sphere of the metals has been represented in Figure 5.
Selected bond distances and angles are listed in Table 4. The
structure contains discrete molecules having crystallographically
imposed symmetry with one molecule of complex and three
acetonitrile molecules in the unit cell.
P(1)-Ag(1)-S(2)a
S(2)a-Ag(1)-S(1)
P(2)-Ag(2)-S(1)
S(1)-Ag(2)-S(2)
145.23(5)
128.94(4)
145.19(5)
128.57(5)
P(1)-Ag(1)-S(1)
P(2)-Ag(2)-S(2)
82.52(5)
79.90(5)
a Symmetry transformations used to generate equivalent atoms: y,
x, -z + 2.
1.833 Å).24,25 The S-C(11) distance, 1.784(4) Å, is within the
accepted range for S-C single bonds.26
(27) Bondi, A. J. Phys. Chem. 1964, 68, 441.
(28) (a) Block, E.; Gernon, M.; Kang, H.; Zubieta, J. Angew. Chem., Int.
Ed. Engl. 1988, 27, 1342. (b) Block, E.; Macherone, D.; Shaikh, S.
N.; Zubieta, J. Polyhedron 1990, 9, 1429. (c) Pe´rez-Lourido, P. A.;
Garc´ıa-Va´zquez, J. A.; Romero, J.; Louro, M. S.; Sousa, A.; Chen,
Q.; Chang, Y.; Zubieta, J. J. Chem. Soc., Dalton Trans. 1996, 2047.
(29) (a) Meiners, J. H.; Clardy, J. C.; Verkade, J. G. Inorg. Chem. 1975,
14, 632. (b) Hollander, F. J.; Coucouvanis, Y. L. Ip, D. Ibid. 1976,
15, 2230. (c) McDonald, W. S.; Pringle, P. G.; Shaw, B. L. J. Chem.
Soc., Chem. Commun. 1982, 861. (d) Khan, Md. N. I.; Staples, R. J.;
King, C.; Fackler, J. P., Jr.; Winpenny, R. E. P. Inorg. Chem. 1993,
32, 5800.
The molecular structure of [Ag4{2-(Ph2P)-6-(Me3Si)C6H3S}4]
(5) is shown in Figure 2, together with the atomic numbering
scheme adopted. For the sake of clarity, a view of the
coordination sphere of the metals has been represented in Figure
3. Selected bond distances and angles are listed in Table 3. The
structure contains discrete molecules having a crystallographi-
cally imposed symmetry with four molecules in the unit cell.
The structure consists of a tetranuclear array of silver atoms,

Neutral Silver(I) Complexes with Arenephosphinothiols
Inorganic Chemistry, Vol. 38, No. 3, 1999 543
by the sulfur plane and the silver plane is 167.46(3)°. The
silver-silver distances [2.8546(7) and 2.8560(8) Å] shorter than
in 5 and even slightly shorter than the distance in metallic silver
(2.88 Å),30 suggest no significant silver-silver interaction.
Moreover, in contrast to 5, where all silver atoms are three-
coordinate in a trigonal disposition around the metal, the four
silver atoms in compound 6 can be divided into two different
pairs according to their coordination environment. One pair
containing Ag(1) and Ag(1′) atoms possesses a very distorted
[AgO2S2] tetrahedral coordination. The other group containing
Ag(2) and Ag(2′) shows a [AgS2] digonal coordination. Thus,
the Ag(1) and Ag(1′) atoms are four coordinated by the oxygen
and the sulfur atoms from two η2(O-µ2-S) bridging bidentate
thiolate ligands acting as five-electron donors. The tetrahedral
geometry around these silver atoms is highly distorted, with
bond angles in the range 158.47(6)-89.86(11)°, which are
significantly different from the value of 109° for regular
tetrahedral geometry. The other two silver atoms are coordinated
by two sulfur atoms, each one from a bridging bidentate thiolate
ligand, resulting in a digonal environment with an S(2)-Ag-
(2)-S(1′) angle of 160.27(6)°.
Figure 4. An ORTEP view of the structure of [Ag4{2-(Ph2PO)-6-(Me3-
Si)C6H3S}4] (6).
The Ag-S bond to the four-coordinated silver atom [Ag-
(1)-S(2) 2.462(2) and Ag(1)-S(2) 2.507(2) Å] is consistently
longer than that to the dicoordinated metal atom [Ag(2)-S(1′)
2.417(2) and Ag(2)-S(2) 2.392(2) Å)]. The larger bond lengths
are shorter than the Ag-S distances found in other examples
of four-coordinated complexes, 2.721-2.568 Å,31 but are similar
to those found in other silver-sulfur complexes, 2.537-2.464
Å, when the metal is three-coordinated.28 However, the shorter
bond lengths are considerably shorter than those in the above
cited complexes but are similar to those found in the dicoor-
dinated complexes, for example, 2.362(8)-2.396(8) Å in
[AgSC(SiMe3)3]4 and 2.387(4)-2.418(4) Å in [AgSCH-
(SiMe3)2]8.8
The Ag-O bond distances are significantly different, 2.489(2)
Å for Ag(1)-O(2) and 2.388(5) Å for Ag(1)-O(1), but fall in
the 2.251(7)-2.64(2) Å range found in the other tetracoordinated
silver-oxygen compounds.32
As in 5, the phenyl groups of 6 are planar, with the sulfur
S(1) and S(2) (0.216, 0.1097 Å) and phosphorus P(1) and P(2)
(0.2914, 0.1437 Å) atoms out the plane of the phenyl rings.
The solvent acetonitrile molecules do not interact with the silver
complex in any significant manner, and there are no noteworthy
intermolecular contacts.
Figure 5. Perspective view of the coordination spheres of the metals
in [Ag4{2-(Ph2PO)-6-(Me3Si)C6H3S}4] (6).
Table 4. Selected Lengths (Å) and Angles (deg) for 6
The Tetranuclear Core in the Structural Chemistry of
Cu(I)- and Ag(I)-Thiolates. The tetranuclear core presents a
persistent structural motif in the chemistry of Cu(I) and Ag(I)
thiolates. The Cu(I)-thiolates exhibit two families of tetranuclear
clusters, the anionic [Cu4(SR)6]2- cages33-42 and the neutral
[Cu4(SR)4]. The former are characterized by an octahedral
arrangement of the six sulfur donor atoms with the Cu(I) centers
occupying half of the triangular faces of the S6 octahedron in a
tetrahedral arrangement. The Cu(I) coordination geometry is
distorted trigonal {CuS3}. The [Cu4(SR)4] class, in the absence
of additional donor groups is restricted to [Cu4{SC6H3-2,6-
Ag(1)-O(1)
Ag(1)-O(2)
Ag(1)-Ag(2)a
Ag(2)-S(1)a
P(2)-O(2)
2.388(5)
2.489(5)
2.8546(7)
2.417(2)
1.483(5)
Ag(1)-S(2)
Ag(1)-S(l)
Ag(2)-S(2)
P(1)-O(1)
2.462(2)
2.507(2)
2.392(2)
1.490(5)
O(1)-Ag(1)-S(2)
S(2)-Ag(1)-O(2)
S(2)-Ag(I)-S(1)
99.92(12) O(1)-Ag(1)-O(2) 106.3(2)
89.86(11) O(1)-Ag(1)-S(1) 92.27(12)
O(2)-Ag(1)-S(1) 103.75(12)
158.47(6)
S(2)-Ag(2)-S(1)a 160.27(6)
a Symmetry transformations used to generate equivalent atoms: -x
+ 1, -y + 2, -z + 1.
The structure of 6 also consists of a tetranuclear array of silver
atoms, but in contrast to 5 the structure of 6 can be best
described as being based on a distorted parallelogram of four
silver atoms, symmetrically disposed around the inversion
center, and held together by four ligands. The silver atoms are
bridged by the sulfur atoms of four thiolate anions. Two of the
sulfur atoms are above the plane formed by the four silver atoms
(+ 0.5144 Å) and the other two below it (-0.3052 Å). The
four sulfur atoms are coplanar, and the dihedral angle formed
(30) Greenwood, N. N.; Earnshaw, A. Chemistry of the Elements; Pergamon
Press: New York, 1989; p 1368.
(31) (a) Dance, I. G.; Fitzpatrick, L. J.; Scudder, M. L. Inorg. Chem. 1984,
23, 2276. (b) Heinrich, D. D.; Fackler, J. P. Jr.; Lahuerta, P. Inorg.
Chim. Acta 1986, 116, 15.
(32) See for example: (a) Lin, W.; Warren, T. H.; Nuzzo, R. G.; Girolami,
G. S. J. Am. Chem. Soc. 1993, 115, 11644. (b) Xu, C.; Corbitt, T. S.;
Hampden-Smith, M. J.; Duesler, E. N. J. Chem. Soc. Dalton Trans.
1994, 2841. (c) Xu, C.; Hampden-Smith, M. J.; Kodas, Y. T.; Duesler,
E. N. Inorg. Chem. 1995, 34, 4767. (d) Powell, J.; Horvath, M. J.;
Lough, A. J. Chem. Soc. Dalton Trans. 1996, 1669.

544 Inorganic Chemistry, Vol. 38, No. 3, 1999
Perez-Lourido et al.
(SiMe3)2}4]42 and [Cu4(SC6H2-iPr3)4].43 Both structures are based
on a Cu4S4 ring with diagonal {CuS2} copper sites. The Cu4S4
rings in both instances fold along one S‚‚‚S axis to produce a
butterfly motif. When additional donor groups are present, the
core geometry is modified to accommodate the expansion of
the Cu(I) coordination sphere. In contrast to the prototypical
[Cu4(SR)4] structures described above, [Cu4{(2-mercaptoethyl)-
picolylamine}4]44 and [Cu4{SC6H4(CH2NMeCH2CH2OMe)}4]45
exhibit a flattened tetrahedral Cu4 core with trigonal {CuS2N}
coordination at the Cu(I) sites, as a consequence of the con-
straints imposed by chelate ring formation. The most unusual
structure is displayed by [Cu4(PPh3)4(SPh)4]38 which consists
of a central {Cu2S2} rhomb linked to 2-folded outer quadrilater-
als. There are two distinct Cu(I) coordination sites, trigonal
{CuPS2} and tetrahedral {CuPS3}. The structure of [Cu4(PPh3)4-
(SPh)4] demonstrates that the cluster shapes adopted by these
thiolates are dictated by an interplay of structure-directing factors
including the coordination flexibility of the metal, steric
influences, and the presence of additional donor groups.
In contrast to the Cu(I) chemistry, there is a single example
of a [Ag4(SR)6]2- cluster, [Ag4(SCH2C6H4CH2S)3]2- 46 which
exhibits the characteristic Ag4 tetrahedron within the S6
octahedron. The organotelluride [Ag4(TeC4H3S)6]2- 47 is struc-
turally analogous.
The prototypical [Ag4(SR)4] structure is provided by [Ag4-
{SC(SiMe3)3}4]8 which consists of an {Ag4S4} ring arranged
in a shallow crown with a maximum deviation of 0.1 Å from
the best least squares plane. The same structure is observed for
the selenium analogue [Ag4{SeCCSiMe3)3}4].48 With less steri-
cally encumbering thiolate ligands, additional aggregation is
observed to give higher oligomers in which the tetranuclear unit
appears as a structural building block. This is most apparent in
49
the structures of [Ag4(SC6H4-o-SiMe3)4]2 and [Ag4{SCH-
(SiMe3)2}4]28 which consist of octanuclear clusters constructed
from two fused {Ag4S4} units. The polymeric [Ag4{SCH2-
(SiMe3)}3(OMe)]8 is also constructed of fused {Ag4S4} units.
The compounds of this study represent the first examples of
the [Ag4(SR)4] family with additional donor groups. The
structure of the {Ag4S4} core of [Ag4{Ph2PO)-6-(Me3Si)C6H3S4]
is similar to that of the shallow crown of [Ag4{SC(SiMe3)3}4].
The Ag-O distances are rather long, and, consequently, the
steric influence of the phosphorus bound phenyl groups may
be minimized. More significantly, the introduction of the oxo-
donor expands the chelate ring {Ag-O-P-C-C-S-} and
relieves chelate strain. In contrast, the structure of [Ag4{2-
(Ph2P)-6-(Me3Si)C6H3S}4] is quite unusual, even for [M4(SR)4]
cores with additional ligation. While the folding of the structure
must reflect some compromise of influences including metal
coordination preferences, ligand steric influences, and chelation,
the relative weights of such factors in determining geometry
remain difficult to assess.
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Acknowledgment. We thank the Xunta de Galicia (XUGA-
20910B93 and XUGA20302B97), Spain, and the National
Science Foundation (E.B.), for financial support. J.Z. acknowl-
edges support from the Department of Energy under grant DE-
FG02-93ERG1571.
Supporting Information Available: X-ray crystallographic files
for the structure determinations of 3, 5, and 6. This material is available
free of charge via the Internet at http://pubs.acs.org.
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