Dinuclear copper(I) and copper(I)/silver(I) complexes with condensed dithiolato ligands

Article abstract of DOI:10.1021/ic8014139

The Cu(III) complex Pr₄N[Cu{S₂C=(t-Bu-fy)} ₂] (1) (t-Bu-fy = 2,7-di-tert-butylfluoren-9-ylidene) reacts with [Cu-(PR₃)₄]ClO₄ in 1:1 molar ratio in MeCN to give the dinuclear complexes [Cu₂{[SC=(t-Bu-fy)]₂S} (PR₃)_n] [n = 2, R = Ph (2a); n = 3, R = To (3b); To = p-tolyl]. The analogue of 2a with R = To (2b) can be obtained from the reaction of 3b with 1/8 equiv of S₈. Compound 2b establishes a thioketene-exchange equilibrium in solution leading to the formation of [Cu ₄{S₂C=(t-Bu-fy)}₂(PTo₃) ₄] (4b) and [Cu₂{[SC=(t-Bu-fy)]₃S}(PTo ₃)₂] (5b). Solid mixtures of 4b and 5b in varying proportions can be obtained when the precipitation of 2b is attempted using MeCN. The reactions of 1 with AgClO₄ and PPh₃, PTo ₃ or PCy₃ in 1:1:4 molar ratio in MeCN afford the heterodinuclear complexes [AgCu{[SC=(t-Bu-fy)]₂S}(PR ₃)₃] [R = Ph (6a), To (6b), Cy (6c)]. Complex 6c dissociates PCy₃ in solution to give the bis(phosphine) derivative [AgCu{[SC=(t-Bu-fy)]₂S}(PCy₃)₂] (7c), which undergoes the exchange of [M(PCy₃)]⁺ units in CD ₂Cl₂ solution to give small amounts of [Cu ₂{[SC=(t-Bu-fy)]₂S}(PCy₃)₂] (2c) and [Ag₂{[SC=(t-Bu-fy)]₂S}(PCy₃)₂] (8c). Complexes 6a and b participate in a series of successive equilibria in solution, involving the dissociation of phosphine ligands and the exchange of [M(PCy₃)]⁺ units to give 2a or 3b and the corresponding disilver derivatives [Ag₂{[SC=(t-Bu-fy)]₂S}(PR ₃)₂] [R = Ph (8a), To (8b)], followed by thioketene-exchange reactions to give [AgCu{[SC=(t-Bu-fy)]₃S](PR ₃)₂}[R = Ph (9a), To (9b)]. Complexes 9a and b can be directly prepared from the reactions of 1 with AgClO₄ and PPh ₃ or PTo₃ in 1:1:3 molar ratio in THF. The crystal structures of 3b, 6b, 6c, 7c, and 9a have been solved by single-crystal X-ray diffraction studies and, in the cases of 7c and 9a, reveal the formation of short Ag...Cu metallophilic contacts of 2.8157(4) and 2.9606(6) A, respectively.

Full text of DOI:10.1021/ic8014139

Inorg. Chem. 2008, 47, 10662-10673
Dinuclear Copper(I) and Copper(I)/Silver(I) Complexes with Condensed
Dithiolato Ligands1
Jose´ Vicente,† Pablo Gonza´lez-Herrero,*,† Yolanda Garc´ıa-Sa´nchez,† and Delia Bautista‡
Grupo de Qu´ımica Organometa´lica, Departamento de Qu´ımica Inorga´nica, Facultad de Qu´ımica,
UniVersidad de Murcia, Apdo. 4021, 30071 Murcia, Spain, and SAI, UniVersidad de Murcia,
Apdo. 4021, 30071 Murcia, Spain
Received July 28, 2008
The Cu(III) complex Pr4N[Cu{S2C)(t-Bu-fy)}2] (1) (t-Bu-fy ) 2,7-di-tert-butylfluoren-9-ylidene) reacts with [Cu-
(PR3)4]ClO4 in 1:1 molar ratio in MeCN to give the dinuclear complexes [Cu2{[SC)(t-Bu-fy)]2S}(PR3)n] [n ) 2, R
) Ph (2a); n ) 3, R ) To (3b); To ) p-tolyl]. The analogue of 2a with R ) To (2b) can be obtained from the
reaction of 3b with 1/8 equiv of S8. Compound 2b establishes a thioketene-exchange equilibrium in solution leading
to the formation of [Cu4{S2C)(t-Bu-fy)}2(PTo3)4] (4b) and [Cu2{[SC)(t-Bu-fy)]3S}(PTo3)2] (5b). Solid mixtures of 4b
and 5b in varying proportions can be obtained when the precipitation of 2b is attempted using MeCN. The reactions
of 1 with AgClO4 and PPh3, PTo3 or PCy3 in 1:1:4 molar ratio in MeCN afford the heterodinuclear complexes
[AgCu{[SC)(t-Bu-fy)]2S}(PR3)3] [R ) Ph (6a), To (6b), Cy (6c)]. Complex 6c dissociates PCy3 in solution to give
the bis(phosphine) derivative [AgCu{[SC)(t-Bu-fy)]2S}(PCy3)2] (7c), which undergoes the exchange of [M(PCy3)]+
units in CD2Cl2 solution to give small amounts of [Cu2{[SC)(t-Bu-fy)]2S}(PCy3)2] (2c) and [Ag2{[SC)(t-Bu-
fy)]2S}(PCy3)2] (8c). Complexes 6a and b participate in a series of successive equilibria in solution, involving the
dissociation of phosphine ligands and the exchange of [M(PCy3)]+ units to give 2a or 3b and the corresponding
disilver derivatives [Ag2{[SC)(t-Bu-fy)]2S}(PR3)2] [R ) Ph (8a), To (8b)], followed by thioketene-exchange reactions
to give [AgCu{[SC)(t-Bu-fy)]3S}(PR3)2] [R ) Ph (9a), To (9b)]. Complexes 9a and b can be directly prepared from
the reactions of 1 with AgClO4 and PPh3 or PTo3 in 1:1:3 molar ratio in THF. The crystal structures of 3b, 6b, 6c,
7c, and 9a have been solved by single-crystal X-ray diffraction studies and, in the cases of 7c and 9a, reveal the
formation of short Ag · · · Cu metallophilic contacts of 2.8157(4) and 2.9606(6) Å, respectively.
Introduction
properties. We have reported the synthesis of mononuclear
Au,2-4 Tl,3 Pd,5,6 Pt,6-8 and Cu9 and homo- and heteropoly-
nuclear M/M′ (M ) Pd, Pt, M′ ) Au, Ag;7,10 M ) Pd, Pt,
M′ ) Ni, Cd, Hg;10 M ) Pd, Pt, M′ ) Au6) derivatives.
Polynuclear copper complexes with thiolato ligands are
of interest as models for the understanding of the structure,
bonding, and function of the active sites of copper-sulfur
enzymes and proteins.11 Silver thiolato complexes often
exhibit similar coordination environments to those of their
copper analogues, and the study of their structures and
spectroscopic features is relevant to the research concerning
the metal-binding sites of copper metallothioneins and the
toxicology of silver and silver-based therapeutic agents.12
One of our research interests concerns the synthesis of
metal complexes with 1,1-ethylenedithiolato ligands and the
study of their structures and chemical and photophysical
* To whom correspondence should be addressed. E-mail: pgh@um.es.
†
Facultad de Qu´ımica, Universidad de Murcia.
SAI, Universidad de Murcia.
‡
(1) (Fluoren-9-ylidene)methanedithiolato complexes. Part 5. For previous
parts, see refs, 4, 6, 8 and 9.
(2) Vicente, J.; Chicote, M. T.; Gonza´lez-Herrero, P.; Jones, P. G. Chem.
Commun. 1997, 2047–2048.
(3) Vicente, J.; Chicote, M. T.; Gonza´lez-Herrero, P.; Jones, P. G.;
Humphrey, M. G.; Cifuentes, M. P.; Samoc, M.; Luther-Davies, B.
Inorg. Chem. 1999, 38, 5018–5026.
(4) Vicente, J.; Gonza´lez-Herrero, P.; Garc´ıa-Sa´nchez, Y.; Jones, P. G.;
Bardaj´ı, M. Inorg. Chem. 2004, 43, 7516–7531.
(5) Vicente, J.; Chicote, M. T.; Mart´ınez-Viviente, E.; Mart´ınez-Mart´ınez,
A. J.; Jones, P. G. Inorg. Chem. 2006, 45, 10434–10436.
(6) Vicente, J.; Gonza´lez-Herrero, P.; Pe´rez-Cadenas, M.; Jones, P. G.;
Bautista, D. Inorg. Chem. 2007, 46, 4718–4732.
(7) (a) Vicente, J.; Chicote, M. T.; Huertas, S.; Bautista, D.; Jones, P. G.;
Fischer, A. K Inorg. Chem. 2001, 40, 2051–2057. (b) Vicente, J.;
Chicote, M. T.; Huertas, S.; Jones, P. G. Inorg. Chem. 2003, 42, 4268–
4274.
10662 Inorganic Chemistry, Vol. 47, No. 22, 2008
10.1021/ic8014139 CCC: $40.75  2008 American Chemical Society
Published on Web 10/15/2008

Dinuclear Copper(I) and Copper(I)/SilWer(I) Complexes
Chart 1
Scheme 1
ions.13 The relatively milder conditions required for the
preparation of 1 can be connected to the stronger electron-
donating character of ligand II as compared to ded. In
addition, we have shown that upon deprotonation of Cu(I)
dithioato complexes of the type [Cu{S2C(t-Bu-Hfy)}(PR3)2]
in the presence of a base, or through their reaction with
p-benzoquinone, dinuclear complexes containing the con-
densed dithiolato ligand {S[(t-Bu-fy))CS]2}2- (III) are
obtained (Chart 1, Scheme 1). This type of reaction had not
been observed for other dithioato complexes of the type
[Cu(S2CR)(PR′3)2]. We concluded that both the presence of
the relatively acidic H9 hydrogen atom in ligand I and the
electron-donating ability of ligand II are crucial for the initial
deprotonation/oxidation steps leading to the formation of the
condensed ligand III.
As part of our research in the field of heteropolynuclear
complexes with 1,1-ethylenedithiolato ligands, we report here
the reactions of the Cu(III) complex 1 with Cu(I) or Ag(I)
phosphino complexes and show that the coordination of 1
to Cu(I) or Ag(I) ions triggers the reduction of the Cu(III)
center leading to dinuclear Cu(I) or Cu(I)/Ag(I) complexes
containing the condensed ligand III, with concomitant
formation of phosphine sulfide. In certain cases, subsequent
processes lead to the formation of dinuclear complexes with
the ligand {S[(t-Bu-fy))CS]3}2- (IV), resulting from the
exchange of units of the thioketene compound (t-Bu-fy))CS
(V, Chart 1).
We have recently described the synthesis of a series of
copper complexes with 2,7-di-tert-butyl-9H-fluorene-9-car-
-
bodithioate [(t-Bu-Hfy)CS2 , I, Chart 1] and (2,7-di-tert-
2-
butylfluoren-9-ylidene)methanedithiolate [(t-Bu-fy))CS2
,
II].9 (Fluoren-9-ylidene)methanedithiolate ligands like II
show remarkable differences with respect to those most
frequently used 1,1-ethylenedithiolato ligands containing
strong electron-withdrawing substituents that affect the redox
and photophysical properties of their metal complexes.4,8
Thus, we have reported that the aerial oxidation of Cu(I)
and Cu(II) complexes containing ligand II afford the
copper(III) complex [Cu{S2C)(t-Bu-fy)}2]- (1),9 while the
only previously reported 1,1-ethylenedithiolato Cu(III) com-
plex [Cu(ded)2]- [ded ) (EtO2C)2C)CS22-] was prepared
by oxidation of a Cu(II) precursor with H2O2, I2, or Cu2+
Experimental Section
General Considerations, Materials and Instrumentation. All
preparations were carried out at room temperature under an
atmosphere of nitrogen using Schlenk techniques except in the cases
indicated. Solvents were dried by standard methods and distilled
under nitrogen before use. The compounds Pr4N[Cu{S2C)(t-Bu-
14
fy)}2]9 (1), [Cu(PR3)4]ClO4 (R ) Ph, To), and [Ag(PPh3)4]ClO4
were prepared following published procedures. All other reagents
were obtained from commercial sources and used without further
purification. NMR spectra were recorded on Bruker Avance 300
or 400 spectrometers usually at 298 K, unless otherwise indicated.
Chemical shifts are referred to internal TMS (1H and 13C{H}) or
external 85 % H3PO4 (31P{H}). 13C{H} NMR spectra were recorded
only for those compounds which do not undergo rapid exchange
processes at room temperature. The assignments of the H and
13C{H} NMR spectra were made with the help of HMBC and
HSQC experiments. Chart 1 shows the atom numbering of the
(8) Vicente, J.; Gonza´lez-Herrero, P.; Pe´rez-Cadenas, M.; Jones, P. G.;
Bautista, D. Inorg. Chem. 2005, 44, 7200–7213.
(9) Vicente, J.; Gonza´lez-Herrero, P.; Garc´ıa-Sa´nchez, Y.; Jones, P. G.;
Bautista, D. Eur. J. Inorg. Chem. 2006, 115–126.
(10) Vicente, J.; Chicote, M. T.; Huertas, S.; Jones, P. G.; Fischer, A. K.
Inorg. Chem. 2001, 40, 6193–6200.
(11) (a) Tolman, W. B. J. Biol. Inorg. Chem. 2006, 11, 261–271. (b) Henkel,
G.; Krebs, B. Chem. ReV. 2004, 104, 801–824. (c) Fujisawa, K.; Imai,
S.; Kitajima, N.; Moro-oka, Y. Inorg. Chem. 1998, 37, 168–169. (d)
Hanss, J.; Kruger, H. J. Angew. Chem., Int. Ed. 1996, 35, 2827–2830.
(12) (a) Salgado, M. T.; Bacher, K. L.; Stillman, M. J. J. Biol. Inorg. Chem.
2007, 12, 294–312. (b) Palacios, O.; Polec-Pawlak, K.; Lobinski, R.;
Capdevila, M.; Gonzalez-Duarte, P. J. Biol. Inorg. Chem. 2003, 8,
831–842. (c) Fujisawa, K.; Imai, S.; Suzuki, S.; Moro-oka, Y.;
Miyashita, Y.; Yamada, Y.; Okamoto, K.-i. J. Inorg. Biochem. 2000,
82, 229–238. (d) Stillman, M. J. Metal Based Drugs 1999, 6, 277–
290. (e) Zelazowski, A. J.; Gasyna, Z.; Stillman, M. J. J. Biol. Chem.
1989, 264, 17091–17099. (f) Krebs, B.; Henkel, G. Angew. Chem.,
Int. Ed. 1991, 30, 769–788.
1
(13) (a) Hollander, F. J.; Caffery, M. L.; Coucouvanis, D. J. Am. Chem.
Soc. 1974, 96, 4682–4684. (b) Coucouvanis, D.; Hollander, F. J.;
Caffery, M. L. Inorg. Chem. 1976, 15, 1853–1860.
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B. W.; White, A. H. J. Chem. Soc., Dalton Trans. 1999, 4047–4055.
Inorganic Chemistry, Vol. 47, No. 22, 2008 10663

Vicente et al.
Table 1. Crystallographic Data for 3b, 6b, 6c·2CH2Cl2, 7c·0.82MeCN·0.18CH2Cl2 and 9a·CHCl3
3b
6b
6c ·2CH2Cl2
7c·0.82MeCN·0.18CH2Cl2
9a·CHCl3
formula
fw
T (K)
C
107H111Cu2P3S3
C
107H111AgCuP3S3
C
100H151AgCl4CuP3S3
C
81.82H116.82AgCl0.36 CuN0.82P2S3
C
103H113AgCl3CuP2S4
1713.13
100(2)
0.71073
monoclinic
P21/c
14.0816(4)
19.5672(5)
32.9459(9)
90
95.330(2)
90
9038.6(4)
4
1757.42
100(2)
0.71073
monoclinic
P21/c
14.2036(8)
19.6400(12)
32.886(2)
90
95.224(2)
90
9135.8(10)
4
1.278
0.616
0.0569
0.1218
1855.51
100(2)
0.71073
monoclinic
P21/n
15.1117(9)
25.9909(16)
25.8898(16)
90
106.858(2)
90
9731.7(10)
4
1.266
0.687
0.0443
1454.29
100(2)
1808.79
100(2)
λ (Å)
0.71073
triclinic
0.71073
triclinic
cryst syst
space group
a (Å)
j
j
P1
P1
14.0694(11)
16.7786(12)
18.5545(13)
66.222(2)
77.685(2)
70.460(2)
3761.8(5)
2
1.284
0.724
0.0453
0.1147
13.0519(5)
14.8549(5)
23.7462(9)
88.700(2)
84.589(2)
77.899(2)
4481.6(3)
2
1.340
0.722
0.0718
0.1409
b (Å)
c (Å)
R (deg)
ꢀ (deg)
γ (deg)
V (Å3)
Z
Fcalcd (Mg m-3
)
1.259
0.641
0.0864
0.1865
µ (mm-1
R1a
)
wR2b
0.1042
a R1 ) ∑||Fo| - |Fc||/∑|Fo| for reflections with I > 2σ(I). b wR2 ) [∑[w(Fo2 - Fc )2]/∑[w(Fo )2]0.5 for all reflections; w-1 ) σ2(F2) + (aP)2 + bP, where
2
2
2
2
P ) (2Fc + Fo )/3 and a and b are constants set by the program.
fluoren-9-ylidene group. Melting points were determined on a
Reichert apparatus and are uncorrected. Elemental analyses were
carried out with a Carlo Erba 1106 microanalyzer. Infrared spectra
were recorded in the range 4000-200 cm-1 on a Perkin-Elmer
Spectrum 100 FT-IR spectrophotometer using Nujol mulls between
polyethylene sheets or KBr pellets.15
for 16 h and filtered through Celite. Partial evaporation of the filtrate
(1 mL) and addition of MeOH (20 mL) led to the precipitation of
a red solid, which was filtered off, recrystallized from CH2Cl2/
MeOH, and vacuum-dried to give 2b. Yield: 60 mg, 71%. Anal.
Calcd for C85H90Cu2P2S3: C, 73.32; H, 6.44; S, 6.83. Found: C,
73.26; H, 6.51; S, 6.39. Mp: 150 °C (dec). IR (KBr, cm-1):
1
X-ray Structure Determinations. Crystals of 3b, 6b,
6c·2CH2Cl2, 7c·0.2CH2Cl2 ·0.8MeCN, and 9a·CHCl3 suitable for
X-ray diffraction studies were obtained from CH2Cl2/MeOH (3b),
CH2Cl2/MeCN (6b, 6c, 7c), or CHCl3/pentane (9a). Numerical
details are presented in Table 1. The data were collected on a Bruker
Smart APEX diffractometer using monochromated Mo-KR radiation
in ω-scan mode. The structures were solved by direct methods,
except for 9a, which was solved by the Patterson method. All of
them were refined anisotropically on F2 using the program
SHELXL-97 (G. M. Sheldrick, University of Go¨ttingen). Restraints
to local aromatic ring symmetry or light-atom displacement factor
components were applied in some cases. The hydrogen atoms were
refined using rigid methyl groups or a riding model. Special features
of refinement: For compounds 3b, 6c and 9a, the Me groups of
one, two, or three of the t-Bu groups, respectively, are disordered
over two positions. The solvent in the crystals of 6c was so badly
resolved that no sensible refinement model could be developed.
For this reason the program SQUEEZE (Prof. A. L. Spek,
University of Utrecht, Netherlands) was used to remove mathemati-
cally the effects of the solvent. For calculations of formula mass
and so forth, an idealized solvent content of two CH2Cl2 molecules
was assumed. For compound 7c, an ill-defined region of residual
electron density was interpreted as the superposition of CH2Cl2 and
MeCN (∼18:82), and their hydrogen atoms were not included in
the refinement.
ν(C)CS2), 1498, 1484, 1456. H NMR (400.9 MHz, CDCl3): δ
4
9.58, 8.61 (both d, JHH ) 1.6 Hz, 1 H each, H1/H8), 7.47, 7.43
3
(both d, JHH ) 8.0 Hz, 2 H each, H4, H5), 7.22, 7.19 (both dd,
4JHH ) 1.6 Hz, 3JHH ) 8.0 Hz, 2 H each, H3, H6), 6.95 (m, 12 H,
3
To), 6.72 (d, JHH ) 7.2 Hz, 12 H, To), 2.22 (s, 18 H, Me, To),
1.23, 1.15 (both s, 18 H each, t-Bu). 13C{1H} NMR (100.8 MHz,
CDCl3): δ 148.9, 148.7 (C2, C7), 140.3 (C8a, C9a), 139.6 (p-C,
2
To), 139.2 (C8a, C9a), 136.5, 136.2 (C4a, C4b), 133.5 (d, JCP
)
3
15 Hz, o-C, To), 131.8 (C9), 129.2 (d, JCP ) 10 Hz, m-C, To),
128.1 (d, JCP ) 41 Hz, i-C, To), 123.8, 123.7, 123.0, 122.9 (C1,
1
C3, C6, C8), 117.9, 117.7 (C4, C5), 34.9, 34.8 (CMe3), 31.6, 31.4
(CMe3), 21.3 (Me, To); CS2 not observed. 31P{1H} NMR (162.3
MHz, CDCl3): δ 5.1 (br).
[Cu2{[SC)(t-Bu-fy)]2S}(PTo3)3] (3b). A solid mixture of 1 (193
mg, 0.20 mmol) and [Cu(PTo3)4]ClO4 (278 mg, 0.20 mmol) was
suspended in MeCN (20 mL) and stirred for 8.5 h. An orange
precipitate gradually formed, which was filtered off, recrystallized
from CH2Cl2 (5 mL)/MeCN (70 mL) and vacuum-dried to give
3b. Yield: 274 mg, 79 %. Anal. Calcd for C107H111Cu2P3S3: C,
75.01; H, 6.53; S, 5.61. Found: C, 74.51; H, 6.74; S, 5.44. Mp:
1
196 °C (dec). IR (KBr, cm-1): ν(C)CS2), 1497, 1483, 1454. H
4
NMR (400.9 MHz, CDCl3): δ 9.58 (s, 2 H, H1/H8), 8.58 (d, JHH
3
) 1.5 Hz, 2 H, H1/H8), 7.48, 7.44 (both d, JHH ) 8.0 Hz, 2 H
each, H4, H5), 7.21, 7.18 (both dd, 4JHH ) 1.5 Hz, 3JHH ) 8.0 Hz,
2 H each, H3, H6), 7.04 (br m, 18 H, To), 6.82 (br, 18 H, To),
2.23 (s, 27 H, Me, To), 1.18, 1.17 (both s, 18 H each, t-Bu). 31P{1H}
NMR (162.3 MHz, CDCl3, 298 K): δ 4.8 (br). 31P{1H} NMR (162.3
MHz, CDCl3, 213 K): δ -0.33 (s), -0.46, -6.62 (AB system, 2JAB
) 117.8 Hz).
[Cu2{[SC)(t-Bu-fy)]2S}(PPh3)2] (2a). A solid mixture of Pr4-
N[Cu{S2Cd(t-Bu-fy)}2] (1) (131 mg, 0.14 mmol) and
[Cu(PPh3)4]ClO4 (167 mg, 0.14 mmol) was suspended in MeCN
and stirred for 22 h. The color of the suspension gradually changed
from green to yellow. The yellow precipitate was filtered off,
washed with MeCN (2 × 5 mL), and vacuum-dried to give 2 as an
orange solid. Yield: 163 mg, 89%. The spectroscopic and analytical
data for this complex have been previously reported.9
Reaction of 1 with [Cu(NCMe)4]PF6 and PTo3. Procedure
A. To a solid mixture of 1 (165 mg, 0.17 mmol), [Cu(NCMe)4]PF6
(64 mg, 0.17 mmol), and PTo3 (179 mg, 0.59 mmol) was added
tetrahydrofuran (THF, 15 mL), and the resulting solution was stirred
for 20 h. The color of the solution gradually changed from dark
brown to red. The solvent was evaporated to dryness and the residue
was dissolved in CH2Cl2 (15 mL). The turbid red solution was
filtered through Celite to remove insoluble impurities and concen-
[Cu2{[SC)(t-Bu-fy)]2S}(PTo3)2] (2b). A solution of 3b (103 mg,
0.06 mmol) and S8 (2 mg, 0.01 mmol) in CH2Cl2 (8 mL) was stirred
(15) For several of the Ag/Cu compounds, the pellets were extracted with
1
CDCl3 and the H NMR spectra showed no decomposition.
10664 Inorganic Chemistry, Vol. 47, No. 22, 2008

Dinuclear Copper(I) and Copper(I)/SilWer(I) Complexes
trated (8 mL). The addition of MeOH (40 mL) led to the
precipitation of the dithiolato complex [Cu4{S2C)(t-Bu-
fy)}2(PTo3)4]·0.5CH2Cl2 (4b) as a yellow solid, which was filtered
off, washed with MeOH (2 mL), and vacuum-dried. Partial
evaporation of the red filtrate (20 mL) led to the precipitation of
2b as a red solid, which was filtered off, washed with MeOH (2 ×
2 mL), and vacuum-dried. Yield: 30 mg of 4b, 16 %; 128 mg of
2b, 54%, based on Cu.
and concentrated (5 mL). The addition of MeCN (40 mL) led to
the precipitation of an orange solid, which was filtered off, washed
with MeCN (2 × 3 mL), and vacuum-dried to give 6b. Yield: 190
mg, 71%. Anal. Calcd for C107H11AgCuP3S3: C, 73.12; H, 6.37; S,
5.47. Found: C, 73.00; H, 6.51; S, 5.43. Mp: 196 °C (dec). IR (KBr,
cm-1): ν(C)CS2), 1497, 1482, 1453. 1H NMR (400.9 MHz,
CDCl3): δ 9.79, 9.38, 8.47, 8.45 (all br, 1 H each, H1, H8), 7.64
(d, JHH ) 8.0 Hz, 2 H, H4, H5), 7.42, 7.41 (both d, JHH ) 8.0
Hz, 1 H each, H4, H5), 7.27-7.12 (m, 4 H, H3, H6), 7.08 (br m,
24 H, To), 6.85 (br m, 24 H, To), 2.23 (s, 27 H, Me, To), 1.25,
1.20, 1.16, 0.93 (all s, 9 H each, t-Bu). 31P{1H} NMR (162.3 MHz,
CDCl3): δ 3.1 (br).
3
3
Procedure B. A solid mixture of 1 (203 mg, 0.21 mmol),
[Cu(NCMe)4]PF6 (80 mg, 0.21 mmol), and PTo3 (201 mg, 0.66
mmol) was suspended in MeCN (20 mL) and stirred for 23 h. The
solvent was evaporated under reduced pressure, and the dark red
residue was treated with CH2Cl2 (20 mL). The resuting turbid red
solution was filtered through Celite to remove insoluble impurities
and concentrated (8 mL). The addition of MeCN (60 mL) led to
the slow precipitation of a dark green solid, which was filtered off,
washed with MeCN (2 × 2 mL), and vacuum-dried. According to
its IR and NMR data, this solid is a mixture of 4b and [Cu2{[SC)(t-
Bu-fy)]3S}(PTo3)2] (5b). Yield: 99 mg. Variable proportions of the
two components were obtained in different preparations (molar ratio
4b:5b from 1:1 to 1:3.6); the IR and NMR data for 5b were obtained
using one of the mixtures with higher content of this complex.
Data for 4b. Anal. Calcd for C128.5H133ClCu4P4S4: C, 69.55; H,
6.04; S, 5.78. Found: C, 69.28; H, 6.24; S, 5.49. Mp: 167 °C (dec).
[AgCu{[SC)(t-Bu-fy)]2S}(PCy3)3] (6c). The compound 6c ·
1.5CH2Cl2 was obtained as an orange solid following the procedure
described for 6b, starting from 1 (282 mg, 0.30 mmol), AgClO4
(63 mg, 0.30 mmol), and PCy3 (378 mg, 1.35 mmol). Yield: 450
mg, 84%. Anal. Calcd for C99.5H150AgCl3CuP3S3: C, 65.91; H, 8.34;
S, 5.31. Found: C, 66.12; H, 8.59; S, 5.15. Mp: 111 °C (dec). IR
(KBr, cm-1): ν(C)CS2), 1502, 1484, 1447. 1H NMR (400.9 MHz,
CD2Cl2, 213 K): δ 9.90, 9.72, 8.57, 8.16 (all s, 1 H each, H1/H8),
3
7.67, 7.64, 7.52, 7.42 (all d, JHH ) 8.0 Hz, 1 H each, H4/H5),
3
7.26, 7.21, 7.10, 7.00 (all d, JHH ) 8.0 Hz, 1 H each, H3/H6),
1.85-1.40 (br m, 63 H, Cy), 1.33, 1.31, 1.21 (all s, 9 H each, t-Bu),
1.20-0.8 (br m, 36 H, Cy), 0.62 (s, 9 H, t-Bu). 31P{1H} NMR
(162.3 MHz, CD2Cl2, 213 K): δ 25.0 (A parts of 2 ABX systems,
1
IR (KBr, cm-1): ν(C)CS2), 1488, 1456. H NMR (400.9 MHz,
4
3
1
1
2JA-B ) 117 Hz, JP-
) 418 Hz, JP-
) 484 Hz), 19.2 (s),
107Ag
109Ag
CDCl3): δ 9.41 (d, JHH ) 1.6 Hz, 2 H, H1, H8), 7.65 (d, JHH
)
4
3
16.6 (B parts of 2 ABX systems, 1JP- Ag ) 340 Hz, 1JP- Ag ) 392
Hz).
107
109
8.0 Hz, 2 H, H4, H5), 7.19 (dd, JHH ) 1.6 Hz, JHH ) 8.0 Hz, 2
3
H, H3, H6), 7.08 (m, 12 H, To), 6.50 (d, JHH ) 7.2 Hz, 12 H,
To), 2.00 (s, 18 H, Me, To), 0.96 (s, 18 H, t-Bu). 13C{1H} NMR
(75.4 MHz, CDCl3): δ 147.7 (C2, C7), 141.2 (C8a, C9a), 138.8
[AgCu{[SC)(t-Bu-fy)]2S}(PCy3)2] (7c). To a solid mixture of
1 (410 mg, 0.43 mmol), AgClO4 (90 mg, 0.44 mmol), and PCy3
(362 mg, 1.29 mmol) was added MeCN (30 mL), and the resulting
suspension was stirred for 18 h. An orange precipitate gradually
formed, which was separated by filtration and dissolved in CH2Cl2
(20 mL). The turbid red solution was filtered through Celite to
remove insoluble impurities and concentrated (10 mL). The addition
of MeCN (40 mL) led to the precipitation of a yellow solid, which
was filtered off, washed with MeCN (2 × 5 mL), and vacuum-
dried to give 7c. Yield: 563 mg, 93%. Anal. Calcd for
C80H114AgCuP2S3: C, 68.37; H, 8.18; S, 6.84. Found: C, 68.18; H,
8.49; S, 6.57. Mp: 150 °C (dec). IR (KBr, cm-1): ν(C)CS2), 1515,
2
(p-C, To), 135.4 (C4a, C4b), 133.8 (d, JCP ) 15 Hz, o-C, To),
1
3
132.8 (C9), 129.9 (d, JCP ) 32 Hz, i-C, To), 129.0 (d, JCP ) 10
Hz, m-C, To), 125.1 (C1, C8), 120.9 (C3, C6), 116.9 (C4, C5),
34.6 (CMe3), 31.6 (CMe3), 21.2 (Me, To); CS2 not observed.
31P{1H} NMR (162.3 MHz, CDCl3): δ -6.1 (s).
Data for 5b. IR (KBr, cm-1): ν(C)CS2), 1499, 1474. 1H NMR
(400.9 MHz, CDCl3): δ 9.28, 8.58, 8.34 (all d, 4JHH ) 1.5 Hz, 2 H
3
each, H1, H8), 7.61, 7.58 (both d, JHH ) 8.0 Hz, 2 H each, H4,
4
3
H5), 7.25, 7.21, 7.08 (all dd, JHH ) 1.6 Hz, JHH ) 8.0 Hz, 2 H
each, H3, H6), 7.03 (m, 6 H, To), 7.01 (d, 3JHH ) 8.0 Hz, 2 H, H4,
3
1
H5), 6.90 (m, 6 H, To), 6.73, 6.42 (both br d, JHH ) 6.8 Hz, 6 H
1483, 1448. H NMR (400.9 MHz, CDCl3): δ 9.73, 9.36, 8.52,
4
each, To), 2.23, 2.02 (both s, 9 H each, Me, To), 1.33, 1.16, 0.83
(all s, 18 H each, t-Bu). 31P{1H} NMR (162.3 MHz, CDCl3): δ
0.2, -3.0 (both br).
8.31 (all d, JHH ) 1.6 Hz, 1 H each, H1, H8), 7.64, 7.63, 7.53,
3
7.42 (all d, JHH ) 8.0 Hz, 1 H each, H4, H5), 7.30, 7.24, 7.19,
3
4
7.09 (all dd, JHH ) 8.0 Hz, JHH ) 1.6 Hz, 1 H each, H3, H6),
1.89-1.45 (br m, 42 H, Cy), 1.43, 1.38, 1.31 (all s, 9 H each, t-Bu),
1.25-0.95 (br m, 24 H, Cy), 0.79 (s, 9 H, t-Bu). 13C{1H} NMR
(100.8 MHz, CDCl3): δ 159.4, 159.3 (br, CS2), 149.7, 148.8, 148.2,
148.1 (C2, C7), 141.1, 140.2, 139.5, 139.0 (C8a, C9a), 137.6, 136.1,
135.6, 135.4 (C4a, C4b), 132.7, 127.9 (br, C9), 124.5, 124.2, 123.7,
123.3, 123.2, 121.5, 121.0 (C1, C8, C3, C6), 117.9, 117.6, 117.4,
[AgCu{[SC)(t-Bu-fy)]2S}(PPh3)3] (6a). A solid mixture of 1
(354 mg, 0.37 mmol), AgClO4 (77 mg, 0.37 mmol), and PPh3 (394
mg, 1.50 mmol) was supended in MeCN (20 mL) and stirred for 3
days. A yellow precipitate gradually formed, which was filtered
off, washed with MeCN (2 × 3 mL) and vacuum-dried to give 6a.
Yield: 595 mg, 98%. Anal. Calcd for C98H93AgCuP3S3: C, 72.15;
H, 5.75; S, 5.90. Found: C, 72.20; H, 5.85; S, 5.56. Mp: 127 °C
1
117.0 (C4, C5), 35.1, 35.0, 34.9, 34.6 (CMe3), 32.0 (d, JCP ) 15
1
(dec). IR (KBr, cm-1): ν(C)CS2), 1517, 1488, 1458. H NMR
Hz, C1, Cy), 31.9, 31.86, 31.84, 30.94 (CMe3), 30.91 (br, C2, C6,
Cy), 30.5 (vdd, N ) 13 Hz, C2, C6, Cy), 27.4-27.0 (m, C3, C5,
Cy), 26.1, 25.7 (C4, Cy). 31P{1H} NMR (162.3 MHz, CDCl3): δ
(400.9 MHz, CDCl3): δ 9.81, 9.43, 8.54, 8.47 (all br, 1 H each,
3
3
H1, H8), 7.65 (d, JHH ) 8.0 Hz, 2 H, H4, H5), 7.43 (dd, JHH
)
8.0 Hz, 4JHH ) 1.8 Hz, 2 H, H3, H6), 7.30-6.94 (br m, 34 H, H4,
H5, H3, H6 + Ph), 1.23, 1.19, 1.14, 0.98 (all s, 9 H each, t-Bu).
31P{1H} NMR (162.3 MHz, CDCl3): δ 4.5 (br).
39.1 (2 d, JP-
) 542 Hz, JP-
) 626 Hz), 20.9 (br).
1
1
107
109
Ag
Ag
[AgCu{[SC)(t-Bu-fy)]3S}(PPh3)2] (9a). A solid mixture of 1
(373 mg, 0.39 mmol) and [Ag(PPh3)4]ClO4 (497 mg, 0.40 mmol)
was suspended in THF (40 mL). After stirring for 3 h, a turbid red
solution was obtained, which was concentrated to dryness. The oily
residue was stirred with CH2Cl2 (15 mL), and the resulting
suspension was filtered through Celite to remove the isoluble
material. The filtrate was concentrated (10 mL), MeCN (50 mL)
was added, and the resulting solution was left to stand for 24 h
[AgCu{[SC)(t-Bu-fy)]2S}(PTo3)3] (6b). A solid mixture of 1
(145 mg, 0.15 mmol), AgClO4 (33 mg, 0.16 mmol), and PTo3 (190
mg, 0.62 mmol) was suspended in MeCN (15 mL) and stirred for
23 h. An orange precipitate gradually formed, which was separated
by filtration and dissolved in CH2Cl2 (10 mL). The turbid red
solution was filtered through Celite to remove insoluble impurities
Inorganic Chemistry, Vol. 47, No. 22, 2008 10665

Vicente et al.
Scheme 2a
under atmospheric conditions, whereupon complex 9a precipitated
as a black microcrystalline solid. Yield: 230 mg, 35%, based on
Cu (70% in view of the equilibrium represented in Scheme 5). Anal.
Calcd for C102H102AgCuP2S4: C, 72.51; H, 6.09; S, 7.59. Found:
C, 72.39; H, 6.26; S, 7.56. Mp: 192 °C (dec). IR (KBr, cm-1):
1
ν(C)CS2), 1499, 1475. H NMR (400.9 MHz, CDCl3): δ 9.37,
4
8.66, 8.51 (all d, JHH ) 1.6 Hz, 2 H each, H1, H8), 7.64, 7.63
3
(both d, JHH )8.0 Hz, 2 H each, H4, H5), 7.25, 7.20 (both dd,
4
3JHH )8.0 Hz, JHH ) 1.6 Hz, 2 H each, H3, H6), 7.18-7.10 (m,
6 H, H4, H5, H3, H6 + Ph), 7.04-6.91 (m, 20 H, Ph), 6.71-6.64
(m, 6 H, Ph), 1.34, 1.11, 0.90 (all s, 18 H each, t-Bu). 13C{1H}
3
NMR (75.4 MHz, CDCl3): δ 153.6 (dd, JCP ) 8.1, 3.0 Hz, CS2),
150.2, 148.9, 148.6 (C2, C7), 140.6 (C8a, C9a), 139.31, 139.29
(C8a, C9a, CS2), 139.1 (C8a, C9a), 136.6, 136.4, 136.0 (C4a, C4b),
133.4 (br d, 2JCP ) 16.2 Hz, o-C, PPh3), 133.3 (d, 2JCP ) 13.2 Hz,
o-C, PPh3), 132.2 (d, 1JCP ) 31 Hz, i-C, PPh3), 131.0 (br d, 1JCP
)
4
33 Hz, i-C, PPh3), 130.3 (t, JCP ) 2.1 Hz, C9), 129.9, 129.2 (br,
p-C, PPh3), 128.5 (br d, 3JCP ) 10.3 Hz, m-C, PPh3), 128.2 (d, 3JCP
) 9.2 Hz, m-C, PPh3), 127.0 (C9), 125.2, 124.6, 124.5, 123.7, 122.2
(C1, C8, C3, C6), 118.4, 118.0, 117.3 (C4, C5), 35.0, 34.9, 34.8
(CMe3), 31.8, 31.7, 31.0 (CMe3). 31P{1H} NMR (162.3 MHz,
1
1
107Ag
109Ag
CDCl3): δ 13.6 (2 d, JP-
) 541 Hz, JP-
) 623 Hz),
1.8 (s).
[AgCu{[SC)(t-Bu-fy)]3S}(PTo3)2] (9b). To a solid mixture of
1 (268 mg, 0.28 mmol), AgClO4 (59 mg, 0.28 mmol), and PTo3
(261 mg, 0.86 mmol) was added THF (20 mL), and the resulting
dark brown solution was stirred for 3 h. The color gradually changed
to dark red. The solvent was evaporated to dryness, the oily residue
was stirred with CH2Cl2 (15 mL), and the resulting suspension was
filtered through Celite to remove the insoluble material. Partial
evaporation of the clear reddish brown filtrate (5 mL) and addition
of MeCN (45 mL) led to the precipitation of a purplish black
microcrystalline solid, which was fitered off, washed with MeCN
(2 × 2 mL), and vacuum dried to give 9b. Yield: 130 mg, 26%,
based on Cu (52% in view of the equilibrium represented in Scheme
5). Anal. Calcd for C108H114AgCuP2S4: C, 73.13; H, 6.48; S, 7.23.
Found: C, 72.95; H, 6.40; S, 7.08. Mp: 188 °C (dec). IR (KBr,
a (i) [Cu(PPh3)4]ClO4 - SPPh3 - PPh3 - Pr4N(ClO4) or [Cu(NCMe)4]-
PF6 + 3PTo3 - SPTo3 - Pr4N(PF6). (ii) [Cu(PTo3)4]ClO4 - SPTo3
Pr4N(ClO4). To ) p-tolyl.
-
complex [Cu2{[SC)(t-Bu-fy)]2S}(PPh3)2] (2a) after 24 h,
which was isolated in 89% yield as an orange precipitate
(Scheme 2). The other products of this reaction were
Pr4N(ClO4), SPPh3, and free PPh3, which were identified in
the mother liquor. We have reported the synthesis of 2a by
reacting [Cu{S2C(t-Bu-Hfy)}(PPh3)2] with Et3N under at-
mospheric conditions or with p-benzoquinone, but in lower
yields (67 or 73%, respectively).9 Curiously, the synthesis
of the analogous PTo3 complex 2b (To ) p-tolyl) was not
fulfilled using the same procedure. Thus, the reaction of 1
with [Cu(PTo3)4]ClO4 in 1:1 molar ratio in MeCN gave the
tris(phosphine) complex [Cu2{[SC)(t-Bu-fy)]2S}(PTo3)3]
(3b) as an orange precipitate. Although its 31P{1H} NMR
spectrum at low temperature shows that 3b is in equilibrium
with the bis(phosphine) derivative 2b and free PTo3 in
solution (Scheme 2), pure 2b could not be obtained through
successive recrystallizations of 3b from CH2Cl2/MeCN.
However, the reaction of 3b with elemental sulfur causes
the displacement of the equilibrium to the formation of
S)PTo3 and 2b (Scheme 2), which can be isolated in 71%
yield.
1
cm-1): ν(C)CS2), 1497, 1474. H NMR (400.9 MHz, CDCl3): δ
4
9.38, 8.67, 8.43 (all d, JHH ) 1.6 Hz, 2 H each, H1, H8), 7.65,
3
7.63 (both d, JHH ) 8.0 Hz, 2 H each, H4, H5), 7.24, 7.20, 7.11
(all dd, 4JHH ) 1.6 Hz, 3JHH ) 8.0 Hz, 2 H each, H3, H6), 7.06 (d,
3JHH ) 8.0 Hz, 2 H, H4, H5), 6.95-6.83 (m, 12 H, To), 6.75, 6.46
3
(both br d, JHH ) 6.8 Hz, 6 H each, To), 2.22, 2.08 (both s, 9 H
each, Me), 1.34, 1.09, 0.90 (all s, 18 H each, t-Bu). 13C{1H} NMR
(75.4 MHz, CDCl3): δ 154.5 (dd, 3JCP ) 11.2, 3.9 Hz, CS2), 149.9,
148.9, 148.6 (C2, C7), 140.7 (C8a, C9a), 139.8 (br, p-C, To),
3
139.23, 139.16, 139.14 (C8a, C9a, CS2), 138.9 (d, JCP ) 1.7 Hz,
p-C, To), 136.6, 136.3, 136.0 (C4a, C4b), 133.4 (br d, 2JCP ) 16.5
2
Hz, o-C + i-C, To), 133.2 (d, JCP ) 13.5 Hz, o-C, To), 130.0 (t,
4JCP ) 2.0 Hz, C9), 129.3 (d, 3JCP ) 11.4 Hz, m-C, To), 128.8 (d,
1
3JCP ) 9.6 Hz, m-C, To), 128.2 (br d, JCP ) 34.8 Hz, i-C, To),
127.1 (C9), 125.0, 124.5 (C1, C8), 124.3 (C3, C6), 123.7 (C1, C8),
122.1, 122.0 (C3, C6), 118.2, 117.9, 117.2 (C4, C5), 35.0, 34.8,
34.7 (CMe3), 31.8, 31.6, 31.0 (CMe3), 24.4, 21.2 (Me, To). 31P{1H}
1
1
107Ag
NMR (162.3 MHz, CDCl3): δ 11.6 (2 d, JP-
) 545 Hz, JP-
We also carried out several attempts to directly obtain
complex 2b by reacting 1 with [Cu(NCMe)4]PF6 and PTo3
in 1:1:3 molar ratio. When this reaction was carried out in
THF, a red solution was obtained, from which the dithiolato
complex [Cu4{S2C)(t-Bu-fy)}2(PTo3)4]9 (4b) (16% yield,
based on Cu) and crude 2b (∼54% yield) were successively
isolated by precipitation with MeOH. However, the latter
was contaminated with small amounts of decomposition
109
) 633 Hz), 0.2 (br).
Ag
Results and Discussion
Synthesis of Dicopper(I) Complexes. The reaction of the
Cu(III) complex Pr4N[Cu{S2C)(t-Bu-fy)}2] (1) with
[Cu(PPh3)4]ClO4 in 1:1 molar ratio in MeCN at room
temperature led to the formation of the dinuclear Cu(I)
10666 Inorganic Chemistry, Vol. 47, No. 22, 2008

Dinuclear Copper(I) and Copper(I)/SilWer(I) Complexes
Scheme 3a
Figure 1. Thermal ellipsoid plot (50 % probablility) of complex 3b. H
atoms and t-Bu and To groups have been omitted for clarity.
The PPh3 and PTo3 derivatives 6a and b are considerably
less stable in solution than the PCy3 complex 6c, and they
establish a series of equilibria in solution leading to the
formation of limited amounts of the dicopper complexes 2a
or 3b, their disilver homologues, [Ag2{[SC)(t-Bu-
fy)]2S}(PR3)2] [R ) Ph (8a), To (8b); see NMR Section],
and the heterodinuclear complexes [CuAg{[SC)(t-Bu-
fy)]3S}(PR3)2] [R ) Ph (9a), To (9b)], containing ligand IV
(Scheme 3). Other species observed could not be identified.
Complexes 9a,b were isolated in the unsuccessful attempts
to prepare the heterodinuclear complexes 7a,b. Thus, the
reactions of 1 with AgClO4 and PPh3 or PTo3 in 1:1:3 molar
ratio in MeCN gave greenish brown precipitates from which
complexes 9a or b can be extracted with CH2Cl2. The other
products of these reactions are S)PR3, Pr4N(ClO4), and
unidentified insoluble materials. Better yields in 9a,b were
obtained using THF as solvent (35% and 26%, respectively,
based on Cu). The PPh3 derivative 9a can be also prepared
by using [Ag(PPh3)4]ClO4 as the silver precursor or by
successive recrystallizations of complex 6a from CH2Cl2/
MeCN.
Crystal Structures of Complexes. The X-ray diffraction
structure of complex 2a has been previously reported by us.9
The condensed dithiolato ligand III binds one of the
[Cu(PPh3)]+ units through the terminal sulfur atoms and the
other through the C)CS2 double bond of a fluoren-9-ylidene
group and one of the terminal sulfur atoms. (Scheme 2). The
PTo3 analogue 2b is expected to present a similar structure,
although this could not be confirmed by means of X-ray
diffraction studies.
The X-ray single-crystal structure analyses of the homodi-
nuclear Cu(I) complex 3b and the heterodinuclear Cu(I)/
Ag(I) complex 6b revealed that these complexes are nearly
isostructural. Different perspective views of their crystal
structures are shown in Figures 1 and 2, respectively.
Selected bond distances and angles are listed in Tables 2
and 3. In both cases, the condensed ligand III is coordinated
to a [Cu(PTo3)]+ unit through both terminal sulfur atoms
and to a [M(PTo3)2]+ unit [M ) Cu (3b), Ag (6b)] through
one of the terminal sulfur atoms and the central one. The
conformation of the condensed ligand is almost identical for
both structures, the two S-C-S planes forming an angle of
91.13° (3b) or 89.02° (6b). The fluoren-9-ylidene fragments
are nearly planar, with their respective mean planes slightly
a
(i) AgClO4 + 3 PR3 - SPR3 - Pr4N(ClO4); (ii) AgClO4 + 4 PR3 -
SPR3 - Pr4N(ClO4). (iii) CH2Cl2/MeCN. To ) p-tolyl.
products that could not be separated. By using MeCN as
the precipitating agent instead of MeOH, a green precipitate
was obtained, which contained 4b and the new ligand IV
complex [Cu2{[SC)(t-Bu-fy)]3S}(PTo3)2] (5b). These two
compounds slowly react with each other in CDCl3 solution
to give 2b (see the NMR section). When the reaction of 1
with [Cu(NCMe)4]PF6 and PTo3 in 1:1:3 molar ratio was
carried out in MeCN, a mixture of 3b, 4b, and 5b was
obtained as an ochre precipitate. Purplish black crystals of
5b can be obtained when suspensions of 2b in MeCN are
allowed to stand for several days. However, the isolated
amounts of 5b were not enough for a complete characteriza-
tion, and the crystals were not suitable for X-ray single crystal
studies. Its H and 31P{1H} NMR data are consistent with
1
its formulation as an analogue of the heterodinuclear
complexes [AgCu{[SC)(t-Bu-fy)]3S}(PR3)2] [R ) Ph (9a),
To (9b)], whose preparation is described in the next section.
Synthesis of Silver(I)/Copper(I) Complexes. By reacting
1 with AgClO4 and PR3 in 1:1:4 molar ratio in MeCN,
complexes [AgCu{[SC)(t-Bu-fy)]2S}(PR3)3] [R ) Ph (6a),
p-To (6b), PCy3 (6c)] were obtained in high yields as yellow
(6a) or orange (6b and c) precipitates (Scheme 3). When
the reaction of 1 with AgClO4 and PCy3 was carried out in
1:1:3 molar ratio, a high yield of the complex [AgCu{[SC)(t-
Bu-fy)]2S}(PCy3)2] (7c) was obtained. The only other
products of the above reactions were Pr4N(ClO4) and the
corresponding S)PR3, which were identified by NMR
spectroscopy. Complex 6c is in equilibrium with 7c and free
PCy3 in solution. In addition, small amounts of [Cu2{[SC)(t-
Bu-fy)]2S}(PCy3)2] (2c), which has been previously reported
by us,9 and the non-isolated disilver derivative [Ag2{[SC)(t-
Bu-fy)]2S}(PCy3)2] (8c; see NMR discussion and Scheme
6) are observed in solutions of 6c or 7c.
Inorganic Chemistry, Vol. 47, No. 22, 2008 10667

Vicente et al.
Figure 2. Thermal ellipsoid plot (50 % probablility) of complex 6b. H
atoms and t-Bu and To groups have been omitted for clarity.
Table 2. Selected Bond Distances (Å) and Angles (deg) for 3b
Figure 3. Thermal ellipsoid plot (50 % probablility) of complex 6c. H
atoms and t-Bu and Cy groups have been omitted for clarity.
Cu(1)-P(2)
Cu(1)-P(1)
Cu(1)-S(3)
Cu(1)-S(2)
Cu(2)-P(3)
Cu(2)-S(1)
Cu(2)-S(3)
2.2605(11)
2.2931(11)
2.3704(11)
2.5625(11)
2.1951(13)
2.2075(12)
2.2599(12)
S(1)-C(30)
S(2)-C(10)
S(2)-C(30)
S(3)-C(10)
C(9)-C(10)
C(29)-C(30)
1.714(4)
1.792(4)
1.807(4)
1.774(4)
1.364(6)
1.372(6)
Table 4. Selected Bond Distances (Å) and Angles (deg) for 6c
Ag(1)-P(3)
Ag(1)-P(2)
Ag(1)-S(3)
Ag(1)-S(2)
Cu(1)-S(1)
Cu(1)-P(1)
Cu(1)-S(3)
2.4182(6)
2.4673(5)
2.6529(5)
2.9282(5)
2.2028(6)
2.2086(6)
2.2624(6)
S(1)-C(30)
S(2)-C(10)
S(2)-C(30)
S(3)-C(10)
C(9)-C(10)
C(29)-C(30)
1.731(2)
1.791(2)
1.792(2)
1.751(2)
1.363(3)
1.382(3)
P(2)-Cu(1)-P(1)
P(2)-Cu(1)-S(3)
P(1)-Cu(1)-S(3)
P(2)-Cu(1)-S(2)
P(1)-Cu(1)-S(2)
S(3)-Cu(1)-S(2)
P(3)-Cu(2)-S(1)
P(3)-Cu(2)-S(3)
S(1)-Cu(2)-S(3)
127.98(4)
118.95(4)
100.19(4)
123.98(4)
98.31(4)
C(30)-S(1)-Cu(2)
C(10)-S(2)-C(30)
C(10)-S(2)-Cu(1)
C(30)-S(2)-Cu(1)
C(10)-S(3)-Cu(2)
C(10)-S(3)-Cu(1)
Cu(2)-S(3)-Cu(1)
S(3)-C(10)-S(2)
S(1)-C(30)-S(2)
111.79(14)
107.58(19)
84.36(13)
108.04(13)
79.37(14)
90.74(14)
101.51(4)
110.8(2)
P(3)-Ag(1)-P(2)
P(3)-Ag(1)-S(3)
P(2)-Ag(1)-S(3)
P(3)-Ag(1)-S(2)
P(2)-Ag(1)-S(2)
S(3)-Ag(1)-S(2)
S(1)-Cu(1)-P(1)
S(1)-Cu(1)-S(3)
136.359(19)
122.669(18)
95.461(17)
109.197(17)
106.186(17)
63.974(15)
127.42(2)
P(1)-Cu(1)-S(3)
C(30)-S(1)-Cu(1)
C(10)-S(2)-C(30)
C(10)-S(3)-Cu(1)
C(10)-S(3)-Ag(1)
Cu(1)-S(3)-Ag(1)
S(3)-C(10)-S(2)
S(1)-C(30)-S(2)
114.72(2)
113.29(7)
107.77(9)
88.40(7)
72.89(4)
113.56(5)
125.36(5)
117.39(4)
92.76(7)
118.2(2)
108.59(2)
113.72(11)
118.39(11)
Table 3. Selected Bond Distances (Å) and Angles (deg) for 6b
112.66(2)
Ag(1)-P(3)
Ag(1)-P(1)
Ag(1)-S(3)
Ag(1)-S(2)
Cu(1)-P(2)
Cu(1)-S(1)
Cu(1)-S(3)
2.4034(8)
2.4689(7)
2.5717(7)
2.7921(7)
2.1981(8)
2.2124(8)
2.2587(8)
S(1)-C(10)
S(2)-C(10)
S(2)-C(30)
S(3)-C(30)
C(9)-C(10)
C(29)-C(30)
1.727(3)
1.798(3)
1.798(3)
1.767(3)
1.377(4)
1.361(4)
[2.7921(7) Å] is much longer. The distances between the
two metal centers [3.587 Å (3b), 3.666 (6b)] are too long to
consider metallophilic interactions.
The crystal structures of the PCy3 complexes 6c (Figure
3, Table 4) and 7c (Figure 4, Table 5) were solved as CH2Cl2
or CH2Cl2/MeCN solvates, respectively. In both cases the
condensed ligand III is coordinated to a [Cu(PCy3)]+ unit
through both terminal sulfur atoms, and to a [Ag(PCy3)2]+
P(3)-Ag(1)-P(1)
P(3)-Ag(1)-S(3)
P(1)-Ag(1)-S(3)
P(3)-Ag(1)-S(2)
P(1)-Ag(1)-S(2)
S(3)-Ag(1)-S(2)
P(2)-Cu(1)-S(1)
P(2)-Cu(1)-S(3)
S(1)-Cu(1)-S(3)
130.71(3)
121.35(2)
97.84(2)
125.58(2)
95.13(2)
67.34(2)
113.82(3)
124.02(3)
117.22(3)
C(10)-S(1)-Cu(1)
C(10)-S(2)-C(30)
C(10)-S(2)-Ag(1)
C(30)-S(2)-Ag(1)
C(30)-S(3)-Cu(1)
C(30)-S(3)-Ag(1)
Cu(1)-S(3)-Ag(1)
S(1)-C(10)-S(2)
S(3)-C(30)-S(2)
111.82(10)
108.28(13)
103.38(9)
85.38(9)
81.21(9)
93.05(9)
98.55(3)
118.45(16)
113.33(15)
rotated with respect to the corresponding S-C-S planes and
forming an angle of 73.41° (3b) or 72.03° (6b) with each
other. The tricoordinated Cu atoms in both structures are in
slightly distorted trigonal planar environments, with very
similar Cu-S distances (range 2.21-2.26 Å). The tetraco-
ordinated Cu or Ag atoms are in highly distorted tetrahedral
environments, mainly because of the small bite of the CS2
moiety and the different M-S distances. The Cu(1)-S(2)
distance in 3b [2.5625(11) Å] is appreciably longer than
Cu(1)-S(3) [2.3704(11) Å], which is attributable to the
expected lower coordination ability of the central S(2) atom,
and both are significantly longer than for the trigonal Cu(2)
center. Analogously, in the case of 6b, the Ag-S(1) distance
[2.5717(7) Å] is normal, while the Ag-S(2) distance
Figure 4. Thermal ellipsoid plot (50 % probablility) of complex 7c. H
atoms and t-Bu and Cy groups have been omitted for clarity.
10668 Inorganic Chemistry, Vol. 47, No. 22, 2008

Dinuclear Copper(I) and Copper(I)/SilWer(I) Complexes
Table 5. Selected Bond Distances (Å) and Angles (deg) for 7c
Ag(1)-P(1)
Ag(1)-S(2)
Ag(1)-Cu(2)
Ag(1)-S(1)
Cu(2)-P(2)
Cu(2)-S(3)
Cu(2)-S(2)
2.3407(7)
2.4052(7)
2.8157(4)
2.8610(7)
2.2191(7)
2.2202(7)
2.2946(7)
S(1)-C(10)
S(1)-C(30)
S(2)-C(10)
S(3)-C(30)
C(9)-C(10)
C(29)-C(30)
1.789(2)
1.799(3)
1.781(3)
1.734(3)
1.355(4)
1.372(3)
P(1)-Ag(1)-S(2)
P(1)-Ag(1)-S(1)
S(2)-Ag(1)-S(1)
P(2)-Cu(2)-S(3)
P(2)-Cu(2)-S(2)
S(3)-Cu(2)-S(2)
C(10)-S(1)-C(30)
171.67(2)
119.55(2)
68.15(2)
124.13(3)
122.28(3)
111.19(3)
C(30)-S(1)-Ag(1) 89.97(8)
C(10)-S(2)-Cu(2) 91.09(8)
C(10)-S(2)-Ag(1) 96.67(8)
Cu(2)-S(2)-Ag(1) 73.57(2)
C(30)-S(3)-Cu(2)
S(2)-C(10)-S(1)
113.25(9)
112.88(14)
118.44(14)
107.38(11) S(3)-C(30)-S(1)
C(10)-S(1)-Ag(1) 81.95(8)
(6c) or a [Ag(PCy3)]+ (7c) unit through one of them, while
the central S atom establishes weaker interactions with the
Ag atoms. The conformations found for the ligand are
slightly more open than that observed for 3b and 6b, with
the two S-C-S planes forming an angle of 86.24° (6c) or
93.49° (7c). The Cu atoms are in slightly distorted trigonal
planar environments, and the Cu-S distances are similar to
the corresponding distances found for 3b and 6b. The
coordination environment of the Ag atom in 6c is appreciably
different to that found for the PTo3 complex 6b, being best
described as trigonal planar (main deviation from the Ag,
P(2), P(3) and S(3) plane, 0.141 Å) with some degree of
distortion toward the tetrahedral geometry because of the
weak interaction with the central S(2) atom [Ag-S(2):
2.9282(5) Å, Ag-S(1): 2.6529(5) Å]. The observed differ-
ences between 6b and 6c are probably a consequence of the
greater steric hindrance of the PCy3 ligand as compared to
PTo3. The coordination environment for the Ag atom in 7c
is practically linear, with a relatively short Ag-S(2) distance
of 2.4052(7) Å and a S(2)-Ag–P(1) angle of 171.67(2)°,
while the Ag-S(1) distance of 2.8610(7) Å is very long and
can be considered as a secondary, much weaker interaction.
The Cu-Ag distance in 6c [3.998 Å] is even longer than
that found for 3b and 6b, while for 7c [2.8157(4) Å] it is
shorter than the sum of the van der Waals radii for these
metals (3.12 Å),16 indicating the presence of a metallophilic
interaction.
The condensed ligand IV in complex 9a (Figure 5, Table
6) adopts a conformation in which consecutive fluoren-9-
ylidene fragments arrange almost perpendicularly to each
other, the mean planes of the terminal fluoren-9-ylidene
fragments forming angles of 88.91° and 91.63° with that of
the central one. The ligand employs the terminal sulfur atoms
S(1) and S(4) to bridge the [Ag(PPh3)]+ and [Cu(PPh3)]+
units and, additionally, the C(9)dC(10) double bond of the
central fluoren-9-ylidene group is coordinated to the Cu atom.
The resulting coordination environments are distorted trigonal
planar for Ag and distorted tetrahedral for Cu. Considering
the C(9)dC(10) bond centroid, the angles around the Cu
atom are close to the ideal value for the tetrahedral geometry,
except for the centroid-Cu-P(1) angle (134.89°). The Cu-S
and Ag-S distances are comparable to the corresponding
Figure 5. Thermal ellipsoid plot (50 % probablility) of complex 9a. H
atoms and t-Bu and Ph groups have been omitted for clarity.
Table 6. Selected Bond Distances (Å) and Angles (deg) for 9a
Ag(1)-P(2)
Ag(1)-S(4)
Ag(1)-S(1)
Ag(1)-Cu(1)
Cu(1)-C(10)
Cu(1)-C(9)
Cu(1)-P(1)
Cu(1)-S(4)
Cu(1)-S(1)
2.3617(12) S(1)-C(30)
2.4747(12) S(2)-C(10)
2.6997(11) S(2)-C(30)
1.759(4)
1.785(4)
1.789(4)
1.781(4)
1.798(4)
1.757(4)
1.404(6)
1.350(6)
1.366(5)
2.9606(6)
2.088(4)
2.208(4)
S(3)-C(50)
S(3)-C(10)
S(4)-C(50)
2.2677(11) C(9)-C(10)
2.2960(12) C(29)-C(30)
2.3989(12) C(49)-C(50)
P(2)-Ag(1)-S(4)
P(2)-Ag(1)-S(1)
S(4)-Ag(1)-S(1)
C(10)-Cu(1)-P(1) 153.68(12) C(10)-S(2)-C(30)
C(9)-Cu(1)-P(1) 116.79(11) C(50)-S(3)-C(10)
C(10)-Cu(1)-S(4) 88.71(11) C(50)-S(4)-Cu(1)
C(9)-Cu(1)-S(4)
P(1)-Cu(1)-S(4)
C(10)-Cu(1)-S(1) 93.63(11)
147.77(4)
110.66(4)
98.66(3)
C(30)-S(1)-Cu(1)
102.87(14)
C(30)-S(1)-Ag(1) 87.62(14)
Cu(1)-S(1)-Ag(1) 70.71(3)
111.05(18)
104.67(19)
108.06(14)
115.48(11) C(50)-S(4)-Ag(1) 98.09(14)
102.41(4) Cu(1)-S(4)-Ag(1) 76.62(4)
S(2)-C(10)-S(3)
103.4(2)
114.5(2)
115.6(2)
C(9)-Cu(1)-S(1)
P(1)-Cu(1)-S(1)
S(4)-Cu(1)-S(1)
104.95(11) S(1)-C(30)-S(2)
103.31(4)
113.53(4)
S(4)-C(50)-S(3)
M-S distances involving bridging S atoms in the structures
of 2a,9 3c, 6b, or 7c. The distance of the Cu atom to the
C(9)dC(10) bond centroid of 2.031 Å is sligthly shorter than
the corresponding distance found for 2a (2.056 Å). As
expected, the C(9)dC(10) bond [1.404(6) Å], which is
coordinated to Cu, is longer than the uncoordinated
C(29)dC(30) and C(49)dC(50) bonds [1.350(6) and 1.366(5)
Å, respectively]. The two metal centers establish a metal-
lophilic contact of 2.9606(6) Å, which is slightly longer than
that found for 7c. We note that only fourteen crystal
(17) (a) Wei, Q. H.; Yin, G. Q.; Zhang, L. Y.; Chen, Z. N. Organometallics
2006, 25, 4941–4944. (b) Seewald, O.; Florke, U.; Egold, H.; Haupt,
H. J.; Schwefer, M. Z. Anorg. Allg. Chem. 2006, 632, 204–210. (c)
Pattacini, R.; Barbieri, L.; Stercoli, A.; Cauzzi, D.; Graiff, C.;
Lanfranchi, M.; Tiripicchio, A.; Elviri, L. J. Am. Chem. Soc. 2006,
128, 866–876. (d) Wei, Q. H.; Yin, G. Q.; Zhang, L. Y.; Shi, L. X.;
Mao, Z. W.; Chen, Z. N. Inorg. Chem. 2004, 43, 3484–3491. (e)
Shorrock, C. J.; Xue, B. Y.; Kim, P. B.; Batchelor, R. J.; Patrick,
B. O.; Leznoff, D. B. Inorg. Chem. 2002, 41, 6743–6753. (f) Fackler,
J. P.; Lopez, C. A.; Staples, R. J.; Wang, S. N.; Winpenny, R. E. P.;
Lattimer, R. P. J. Chem. Soc., Chem. Commun. 1992, 146–148. (g)
Abu-Salah, O. M.; Hussain, M. S.; Schlemper, E. O. J. Chem. Soc.,
Chem. Commun. 1988, 212–213. (h) Freeman, M. J.; Orpen, A. G.;
Salter, I. D. J. Chem. Soc., Dalton Trans. 1987, 1001–1008. (i)
Freeman, M. J.; Green, M.; Orpen, A. G.; Salter, I. D.; Stone, F. G. A.
J. Chem. Soc., Chem. Commun. 1983, 1332–1334.
(16) Bondi, A. J. Phys. Chem. 1964, 68, 441–451.
Inorganic Chemistry, Vol. 47, No. 22, 2008 10669

Vicente et al.
1
Table 7. H NMR Resonances of the H1/H8 Atoms for the Complexes
Mentioned in This Worka
compd
δ(H1/H8)
2a
2b
2c
3b
9.64, 8.66
9.58, 8.61
9.61, 8.55
9.58, 8.58 (298 K)
10.22, 9.10, 8.56, 8.40 (213 K)
9.41
9.28, 8.57, 8.34
9.81, 9.43, 8.54, 8.47
9.79, 9.38, 8.47, 8.45
9.90, 9.72, 8.57, 8.16
9.73, 9.36, 8.52, 8.31
9.77, 8.58
4b
5b
6a
6b
6c
7c
8a
8b
8c
9a
9b
9.74, 8.54
9.68, 8.52
9.37, 8.66, 8.51
9.38, 8.67, 8.43
Figure 6. NMR spectra of a mixture of 4b and 5b (∼1.2:2 molar ratio) at
different times after dissolution in CDCl3, showing the gradual formation
of 2b (H1 and H8 resonances).
a ppm, CDCl3 solution.
The 1H NMR spectrum of 3b at room temperature shows
two signals for the H1/H8 protons, while the resonances of
the aromatic protons of the PTo3 ligands are broad and only
one signal for the Me groups of the phosphines is observed.
The 31P{1H} NMR spectrum shows a very broad signal at
4.8 ppm. These data suggested the existence of exchange
processes in solution, which were investigated by means of
structures in the Cambridge Structural database display
metallophilic Ag · · ·Cu contacts.17 Most of them correspond
to high-nuclearity clusters, which may include other metals,
and the Ag-Cu distances range from 2.575 to 3.238 Å. At
the time of submission of this article, no structural data for
dinuclear Ag/Cu complexes showing short metallophilic
contacts had been deposited.
1
low-temperature NMR measurements. The H and 31P{1H}
NMR spectra of 3b at 213 K in CDCl3 showed the signals
corresponding to complexes 2b, 3b, and free PTo3. Complex
3b gives rise to the four expected resonances for the H1/H8
protons (10.22, 9.10, 8.56, and 8.40 ppm) due to two
inequivalent t-Bu-fy groups, and the [Cu(PTo3)2]+ unit gives
an AB system in the 31P{1H} NMR spectrum (-0.46, -6.62
ppm; 2JAB ) 117.8 Hz), while the [Cu(PTo3)]+ unit gives a
singlet at -0.33 ppm (see Supporting Information). The ratio
2b/3b estimated from the integration of the H1/H8 reso-
nances is approximately 1:3. The signals observed at room
temperature are thus the result of a complex dynamic process
involving the dissociation and exchange of the phosphine
ligands, eventually leading to the equivalence of the t-Bu-
fy groups.
NMR Spectra, Phosphine Dissociation and Dynamic
Behavior. The H NMR spectra of the complexes with
1
condensed dithiolato ligands show the resonances of the H1/
H8 protons of the fluoren-9-ylidene groups (see Chart 1 for
the atom numbering) at high frequencies (range 10.2-8.2
ppm; Table 7) and are useful for the identification of the
different complexes in mixtures because they usually do not
overlap with any other signals. Therefore, in discussing the
1H NMR spectra, we will only mention the H1/H8 reso-
nances; the H3/H6, H4/H5 and t-Bu signals are reported in
the Experimental Section.
The dicopper complex 2b, like its already reported
analogues with PPh3 (2a), PCy3 (2c), and dppf,9 gives rise
to two resonances for the H1/H8 protons instead of the
expected four resonances in view of the crystal structure of
2a, which shows the two t-Bu-fy groups of the condensed
dithiolate III in different environments (Scheme 2). We have
proposed a dynamic process that causes the copper atoms
to interchange their coordination environments, or a different,
C2-symmetrical structure of the complexes in solution.9
The room temperature 1H NMR spectra of complexes 6a-c
and 7c show in the H1/H8 region the expected four
resonances of the same intensity and a few others of low
intensity corresponding to other complexes. In the cases of
the PPh3 or PTo3 derivatives 6a or b, the additional signals
that emerge gradually are due to 2a, 8a and 9a or 3b, 8b
and 9b, respectively, and to other unidentified species (see
1
1
The H NMR spectrum of 2b in CDCl3 also reveals the
Supporting Information). Despite the fact that the H NMR
show well resolved signals, the 31P{1H} NMR spectra of
solutions of 6a and b show a very broad resonance, indicating
that phosphine dissociation and exchange processes take
presence of very small amounts of the dithiolato complex 4b
and the ligand IV complex 5b (Scheme 2), which give rise to
one or three resonances, respectively, for the H1/H8 protons.
The NMR data for 5b are discussed below, together with those
of its heterodinuclear analogues 9a and b. The presence of 4b
and 5b in solutions of 2b suggests the existence of an
equilibrium which is almost entirely displaced towards the
formation of 2b in CDCl3. In fact, when the solid mixtures of
4b and 5b, obtained from the reaction of 1 with
[Cu(NCMe)4]PF6 and PTo3 in 1:1:3 molar ratio in MeCN, are
1
place. In contrast, the H and 31P{1H} NMR spectra of the
PCy3 derivatives 6c and 7c show only very small amounts
of the dicopper and disilver complexes 2c and 8c, and their
31P resonances resolve clearly. At 213 K, the 31P{1H} NMR
spectrum of 6c shows the resonances arising from the
[Ag(PCy3)2]+ unit as the A and B parts of two ABX systems
because of the coupling of the phosphorus atoms with each
other and the two isotopes of silver, while the [Cu(PCy3)]+
unit gives rise to a somewhat broad singlet (Figure 7). As
1
dissolved in CDCl3, the H NMR spectra show the gradual
transformation of the mixture into 2b (Figure 6).
10670 Inorganic Chemistry, Vol. 47, No. 22, 2008

Dinuclear Copper(I) and Copper(I)/SilWer(I) Complexes
exchange, if it exists, is negligible, which contrasts with the
solution behavior of 6c (see above).
Since complexes 8a-c could not be isolated, their NMR
data (see Table 7 for the chemical shifts of the two H1/H8
1
resonances) have been taken from the H NMR spectra of
the solutions in which they form, namely those of 6a-c and
7c in CDCl3 or CD2Cl2. In the case of the PCy3 complex 8c,
the assignment is straightforward because it forms along with
the dicopper complex 2c9 through the exchange of [Ag-
(PCy3)]+ and [Cu(PCy3)]+ units between molecules of 7c.
Moreover, the 31P{1H} NMR spectra of 6c and 7c in CDCl3
show the resonance corresponding to the equivalent PCy3
ligands in 8c as two doublets centered at 38.50 ppm (1JP-
1
107Ag
109Ag
) 512 Hz, JP-
) 590 Hz). Figure 8 shows the
31P{1H} NMR resonance of 8c in a solution of 7c in CD2Cl2,
which remains unchanged between 233 and 293 K. The
observed Ag-P couplings are consistent with [Ag(PCy3)]+
units that do not undergo significant phosphine dissociation.
The NMR spectra of 6a and b could not be used to obtain
the 31P{1H} NMR data for 8a and b, because of phosphine
Figure 7. Variable-temperature 31P{1H} NMR spectra of a solution of 6c
in CD2Cl2.
1
exchange processes, but their H NMR data allowed us to
assign the H1/H8 chemical shifts of the 8a and b protons
because of their similarity with those found for 8c.
1
The H NMR spectra of the heterodinuclear complexes
9a and b, containing the condensed ligand IV, show the three
resonances of the same intensity for the H1/H8 protons
expected in view of the crystal structure of 9a. The 31P{1H}
NMR spectra show the resonance of the P atom bonded to
Ag as two doublets and one singlet assignable to the P atom
1
bonded to Cu. The H NMR data of complex 5b are very
similar to those of its heteronuclear analogues 9a and b. Not
only do the number of aromatic signals and t-Bu groups
match but also their chemical shifts are almost identical to
those found for the PTo3 derivative 9b. Moreover, the
31P{1H} NMR spectrum of 5b shows two resonances at room
temperature because of two [Cu(PTo3)]+ units in different
coordination environments, and one of them almost coincides
with the signal assigned to the [Cu(PR3)]+ unit in 9a and b.
Therefore, the NMR data of 5b indicate that this complex
has essentially the same structure as its heterodinuclear
derivatives 9a and b.
IR Spectra. The solid state IR spectra of the complexes
with condensed ligand III 2b, 3b, 6a-c, and 7c show three
bands in the range 1517-1447 cm-1 assignable to ν(C)CS2)
modes18 (see the Experimental Section). Notably, these bands
coincide in energy for the isostructural complexes 3b and
6b. Complexes 5b, 9a, and 9b, containing ligand IV, give
rise to two bands at around 1499 and 1475 cm-1; the very
similar patterns and energies of the absorptions observed for
these complexes also suggest that they have the same
structure in the solid state.
Figure 8. Variable-temperature 31P{1H} NMR spectra of a solution of 7c
in CD2Cl2. The marked signals correspond to 2c (*) and 8c (b).
the temperature rises, the resonances of the [Ag(PCy3)2]+
unit broaden and the [Cu(PCy3)]+ singlet shifts to higher
frequencies. At room temperature, the observed signals
essentially correspond to the bis(phosphine) complex 7c and
free PCy3, suggesting a very high degree of dissociation.
The 31P{1H} NMR spectra of complex 7c in CD2Cl2 at
temperatures between 233 and 293 K (Figure 8) show subtle
changes that affect mainly the resonance arising from the
[Ag(PCy3)]+ unit, which is observed at 233 K as two doublets
1
centered at 39.83 ppm (1JP-
) 547 Hz, JP-
) 631
107Ag
109Ag
Hz), in agreement with the structure found in the solid state.
As the temperature rises to 253 K, the doublets broaden and
then sharpen again and shift to 39.45 ppm at room temper-
ature. The observed changes are probably due to the
migration of the [Ag(PCy3)]+ unit from one of the terminal
S atoms to the other, which may involve intermediate species
with different bonding environments for the Ag atom. The
observation of P-Ag couplings in 7c indicates that phosphine
Mechanism of Formation. The lability of Cu(I)-S and
Ag(I)-S bonds is evidenced by the great variability of
structures and coordination environments found in the
(18) Jensen, K. A.; Henriksen, L. Acta Chem. Scand. 1968, 22, 1107–1128.
Inorganic Chemistry, Vol. 47, No. 22, 2008 10671

Vicente et al.
Scheme 4a
Scheme 5a
a
t-Bu-fy groups have been omitted.
Scheme 6a
a
M ) Cu, Ag.
thiolato complexes of these metals19 and the numerous cluster
transformation examples reported in the literature.20 Although
it is difficult to propose a simple reaction path for the
formation of the our dinuclear Cu(I) or Cu(I)/Ag(I) com-
plexes with condensed dithiolato and phosphine ligands,
some of the key steps can be rationalized from the available
experimental data. The formation from 1 of the dinuclear
complexes with ligand III involves the reduction of Cu(III)
to Cu(I) and the sulfur abstraction by one of the phosphines
to give phosphine sulfide. Since complex 1 is not reduced
by free phosphines, it is reasonable to assume that the
dithiolate condensation is triggered by the coordination of
one of the sulfur atoms of 1 to Cu(I) or Ag(I) (Scheme 4)
with the concomitant displacement of one of the phosphine
ligands of the precursor [M(PR3)4]+. This should weaken the
stabilizing effect of the π donation of the sulfur atoms on
the Cu(III) center, making it more susceptible to reduction.
The reduction of the Cu(III) center could take place through
the reductive elimination of two of the thiolate functions to
form a disulfide-bridged dinuclear Cu(I) intermediate such
as B (Scheme 4, path 1), which would then undergo sulfur
abstraction by the displaced phosphine. Tetraalkylthiuram
disulfides R2NC(S)SSC(S)NR2 have been reported to undergo
a similar reaction when treated with Cu(I) halides in the
presence of PPh3, which leads to the formation of complexes
a
t-Bu-fy groups have been omitted.
containing the corresponding monosulfide R2NC(S)SC(S)-
NR2.21 An alternative reduction process could involve the
direct attack of a phosphine to one of the sulfur atoms of
the dithiolato ligand (Scheme 4, path 2). In either case, the
condensed ligand III in 3b and 6a-c presumably results from
the nucleophillic attack of a dithiolate to the thioketene
compound (2,7-di-tert-butylfluoren-9-ylidene)methanethione
(V, Chart 1), which may exist as a coordinated ligand
(intermediate C) or as short-lived free species after the sulfur
abstraction.22 As demonstrated for 3b and 6c, these com-
plexes are in equilibrium with the corresponding bis(phos-
phine) derivatives 2b and 7c and free phosphine in solution.
Probably, the greater tendency to dissociate phosphine of
3a as compared to 3b leads to the isolation of complex 2a
instead of 3a.
(19) (a) Su, W. P.; Hong, M. C.; Weng, J. B.; Liang, Y. C.; Zhao, Y. J.;
Cao, R.; Zhou, Z. Y.; Chan, A. S. C. Inorg. Chim. Acta 2002, 331,
8–15. (b) Blower, P. J.; Dilworth, J. R. Coord. Chem. ReV. 1987, 76,
121. (c) Dance, I. G. Polyhedron 1986, 5, 1037.
(20) (a) Coucouvanis, D.; Kanodia, S.; Swenson, D.; Chen, S. J.; Stude-
mann, T.; Baenziger, N. C.; Pedelty, R.; Chu, M. J. Am. Chem. Soc.
1993, 115, 11271–11278. (b) Coucouvanis, D.; Swenson, D.; Baen-
ziger, N. C.; Pedelty, R.; Caffery, M. L.; Kanodia, S. Inorg. Chem.
1989, 28, 2829–2836. (c) Fackler, J. P.; Staples, R. J.; Liu, C. W.;
Stubbs, R. T.; Lopez, C.; Pitts, J. T. Pure Appl. Chem. 1998, 70, 839–
844. (d) Liu, C. W.; Staples, R. J.; Fackler, J. P Coord. Chem. ReV.
1998, 174, 147–177. (e) Kanodia, S.; Coucouvanis, D. Inorg. Chem.
1982, 21, 469–475.
As mentioned in the Synthesis of Dicopper Complexes
and NMR Sections, complex 2b is in equilibrium with 4b
and 5b in solution (Scheme 2). This equilibrium is repre-
sented in Scheme 5 as the reaction between two ligands III
(as those present in 2b) to give a dithiolate and ligand IV
(21) Victoriano, L. I.; Garland, M. T.; Vega, A.; Lo´pez, C. J. Chem. Soc.,
Dalton Trans. 1998, 1127–1132.
10672 Inorganic Chemistry, Vol. 47, No. 22, 2008

Dinuclear Copper(I) and Copper(I)/SilWer(I) Complexes
(present in 4b and 5b, respectively), and can be described
as an exchange of thioketene units.
the spectra of 6a,b but whose nature could not be established.
Correspondingly, the maximum possible yield of 9a,b is 50%
with respect to the initial equivalents of Cu and Ag.
Scheme 6 summarizes our proposal for the solution
equilibria in which the heterodinuclear Cu/Ag derivatives
are involved: (a) phosphine dissociation equilibrium between
complexes 6 and 7, (b) intermolecular exchange of [Cu(P-
Cy3)]+ and [Ag(PCy3)]+ units between molecules of 7 to give
homodinuclear complexes of Cu (2) and Ag (8), and (c)
exchange of thioketene units between molecules of 7 to give
ligand IV complexes 9 and other species. Depending on the
phosphine ligand these equilibria lead to the observation of
different species in solution. Thus, solutions of the PCy3
complex 6c in CDCl3 contain 7c, free PCy3, and small
amounts of the dicopper and disilver derivatives 2c and 8c,
respectively, which are also observed in solutions of 7c.
Probably, the great steric requirement of PCy3 prevents the
thioketene exchange between molecules of 7c to give 9c.
Complex 6a or b is in equilibrium with the dicopper
complex, 2a or 3b (not shown in Scheme 6), the disilver
complexes 8a or b, the heterodinuclear complexes 9a or b,
containing the ligand IV, and unidentified species. The
presence of complexes 7a or b due to phosphine dissociation
is also expected in these solutions, and it is reasonable to
assume that they are involved in the formation of complexes
9a and b because all attempts to prepare the 7a or b (see
above) invariably led to the formation of 9a or b. This is
also supported by the fact that the thioketene-exchange
equilibrium observed for the homodinuclear Cu(I) complexes
takes place from a bis(phosphine) derivative (2b) and not
from the parent tris(phosphine) complex (3b). Moreover, the
the solutions of complexes 6a or b produce only limited
amounts of 9a or b, suggesting that the thioketene-exchange
process requires the previous dissociation of phosphine to
give 7a or b. In view of the thioketene-exchange equilibrium
represented in Scheme 5, the synthesis of complexes 9a,b
requires the simultaneous formation of the same number of
equivalents of dithiolato complexes of Cu(I) and Ag(I), which
would account for the unassigned NMR signals observed in
Conclusions
The reactions of the Cu(III) complex Pr4N[Cu{S2C)(t-
Bu-fy)}2] (1) with [Cu(PR3)4]ClO4 (R ) Ph or To) in 1:1
molar ratio or with AgClO4 and PR3 (R ) Ph, To or Cy) in
1:1:4 molar ratio lead to the formation of a new type of
dithiolato complex [MCu{[SC)(t-Bu-fy)]2S}(PR3)3] (M )
Cu or Ag), containing a sulfide-bridged dithiolate, formally
2-
resulting from the condensation of two (t-Bu-fy))CS2
ligands and removing of one S2- ion. The process involves
formation of S)PR3 and probably a thioketene complex,
which by a thiolato/thioketene coupling affords the new
dithiolato ligand. These complexes undergo phosphine dis-
sociation equilibria leading to the formation of the corre-
sponding bis(phosphine) derivatives [MCu{[SC)(t-Bu-
fy)]2S}(PR3)2], which when M ) Ag may undergo subsequent
exchange processes to give small amounts of dicopper and
disilver complexes. Some of these dinuclear complexes
undergo a thioketene-exchange process leading to the forma-
tion of a dithiolato complexes and new dinuclear complexes
of the type [MCu{[SC)(t-Bu-fy)]3S}(PR3)2], containing
another new type of dithiolato ligand formally resulting from
2-
the condensation of three (t-Bu-fy))CS2 ligands and
removing of two S2- ions. The present work is the first study
on the reactivity of a Cu(III) 1,1-ethylenedithiolato complex.
The observed reactions are unprecedented in the chemistry
of dithiolato complexes and have allowed the isolation of a
series of derivatives with new types of dithiolato ligands.
Acknowledgment. We thank Ministerio de Educacio´n y
Ciencia (Spain), FEDER (CTQ2004-05396 and CTQ2007-
60808/BQU) for financial support. Y.G.-S. thanks Ministerio
de Educacio´n y Ciencia (Spain) for a grant.
Supporting Information Available: Crystallographic data in
CIF format for 3b, 6b, 6c ·2CH2Cl2, 7c ·0.2CH2Cl2 ·0.8MeCN, and
(22) (a) Raasch, M. S. J. Org. Chem. 1970, 35, 3470–3483. (b) Green,
M.; Osborn, R. B. L.; Stone, F. G. A. J. Chem. Soc., A 1970, 944–
946. (c) Raasch, M. S. J. Org. Chem. 1972, 37, 1347–1356. (d) Harris,
S. J.; Walton, D. R. M. J. Chem. Soc., Chem. Commun. 1976, 1008–
1009. (e) Umland, H.; Behrens, U. J. Organomet. Chem. 1983, 273,
C39–C42. (f) Benecke, J.; Behrens, U. J. Organomet. Chem. 1989,
363, C15–C18. (g) Ziegler, W.; Wormsba¨cher, D.; Behrens, U. J.
Organomet. Chem. 1992, 431, C11–C16.
9a·CHCl3, low-temperature H and 31P{1H} NMR spectra of 3b,
1
and 1H NMR spectra of 6a and b at different times after dissolution.
This material is available free of charge via the Internet at
http://pubs.acs.org.
IC8014139
Inorganic Chemistry, Vol. 47, No. 22, 2008 10673