Mono and polynuclear silver(I) complexes with thiosaccharine and triphenylphosphine or 2,2′-bipyridine. Synthesis, spectroscopic and structural characterization

Article abstract of DOI:10.1016/j.molstruc.2006.11.071

Reaction of Ag₆(tsac)₆ (tsac^- = thiosaccharinate anion) with PPh₃ and 2,2′-bipyridine (bipy) ligands give rise to three new silver-thiosaccharinate complexes, [Ag(tsac)(PPh₃)₃], [Ag₄

Full text of DOI:10.1016/j.molstruc.2006.11.071

Journal of Molecular Structure 841 (2007) 110–117
www.elsevier.com/locate/molstruc
Mono and polynuclear silver(I) complexes with thiosaccharine
and triphenylphosphine or 2,2Ј-bipyridine. Synthesis, spectroscopic
and structural characterization
Mariana Dennehy a, Oscar V. Quinzani a,¤, Michael Jennings b
a Departamento de Química, Universidad Nacional del Sur, Avda. Alem 1253 B8000CPB Bahía Blanca, Argentina
b X-ray Structures Western, Chemistry Department, University of Western Ontario, London, Ont., Canada N6A 5B7
Received 11 September 2006; received in revised form 28 November 2006; accepted 30 November 2006
Available online 22 January 2007
Abstract
Reaction of Ag6(tsac)6 (tsac¡ D thiosaccharinate anion) with PPh3 and 2,2Ј-bipyridine (bipy) ligands give rise to three new silver-thio-
saccharinate complexes, [Ag(tsac)(PPh3)3], [Ag4(tsac)4(PPh3)3] , and [Ag2(tsac)2(bipy)2]. Their crystal structures established by single-crys-
tal X-ray diVraction and IR spectroscopic characterizations are reported here. In each complex a singular coordination mode for the
thiosaccharinate ligands is observed. The most important features of the diVerent coordination modes of the thionates are discussed.
© 2006 Elsevier B.V. All rights reserved.
Keywords: Silver(I) complexes; Heterocyclic thiones; Thiosaccharine; Crystal structure
1. Introduction
thiosaccharine (the thione form of saccharine,
C6H4S(O)2NHC(S)) our research group have studied several
new compounds of Cd(II), Tl(I), and Pd(II) [5]. This work
was recently reviewed by E. Baran and V. Yilmaz [6]. As it is
well known for other heterocyclic thiones, thiosaccharine has
a tautomeric equilibrium in solution and in its thiol form can
act as a good coordinating agent for soft metals, building
mononuclear and polynuclear structures with or without the
presence of additional ligands. Recently, our research group
has structurally characterized polynuclear Ag(I) and Cu(I)
thiosaccharinates, having hexanuclear [Ag6(tsac)6] and tetra-
nuclear [Cu4(tsac)4] molecular units, respectively [7]. In these
compounds the thiosaccharinate anion acts as a bridging tri-
dentate ligand, with the exocyclic sulfur atom and the endo-
cyclic nitrogen atom simultaneously bonded to three metal
atoms, joining the corners of triangular faces of the polyhe-
dra formed by the metal atoms. Hexanuclear and tetranu-
clear clusters are common structures in the coordination
chemistry of silver(I), and depending on the nature of the
ligands and on electronic demands of the metal d10 closed
electronic conWguration, coordination numbers can range
from 2 to 5. Usually, trisubstituted phosphine, bipyridine or
Silver (I) complexes with thiolate or heterocyclic thioami-
date (thionate) ligands have been widely studied because they
have shown a great tendency to form cluster and polymer
structures [1–3] with potential application in catalysis and
inorganic–organic hybrid conductors [2c]. A considerable
amount of work has been centered around the coordination
chemistry of heterocyclic thiones, versatile S,N ligands capa-
ble to bind to metals in a great variety of coordination forms:
N or S-monodentate, ꢀ2-S-bridge, N,S-chelate, ꢀ2-N,S-
bridge, ꢀ2-N,S-(ꢀ2-S)-bridge, ꢀ3-N,S-(ꢀ2-S, ꢀ1-N)-bridge. A
rich Weld of mononuclear, binuclear and complex polynu-
clear coordination compounds has then developed [3]. Sev-
eral reviews dealing with the coordination of these
heterocyclic thione ligands have been published since the Wrst
leading works of E.S. Rapper [4]. In the last few years, with
the aim to further exploring the coordination behavior of
*
Corresponding author. Tel.: +54 291 4595159; fax: +54 291 4595160.
E-mail address: quinzani@criba.edu.ar (O.V. Quinzani).
0022-2860/$ - see front matter © 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2006.11.071

M. Dennehy et al. / Journal of Molecular Structure 841 (2007) 110–117
111
phenanthroline molecules are used to control the stereo-
chemistry and/or nuclearity of silver complexes, and when
halogenides or thiolates are the counterions, they can also
coordinate to metal centers as monodentate or bridged
bidentate ligands [1,8–13]. Bowmaker et al. have character-
ized a number of silver-2,2Ј-bipyridine complexes with diVer-
ent oxyanions [14]. By controlling the experimental
conditions, diverse structures, like the tetranuclear
(PPh3)2Ag4(MT)4 (MTD2-mercaptothiazoline) [11], dinu-
clear [Ag(PPh3)(bzimtH2)Br]2 (bzimtH2 Dbenz-1,3-imidazo-
line-2-thione) [12] and mononuclear [Ag(PPh3)2(py2SH)Cl]
(py2SHDpyridine-2-thione) [13] compounds have been
obtained by other authors from Ag–triphenylphosphine–thi-
one mixtures.
With the aim to analyze the inXuence of these bulky
ligands on the molecular geometry of ternary silver(I) thio-
saccharinate complexes, and on the coordination modes of
the thiosaccharine ligand, three new silver complexes are
reported in the present study. These complexes display
diVerent coordination modes for the thiosaccharinato
ligand: tris(triphenylphosphine)-ꢀ1-S-(thiosaccharinato)sil-
ver(I), [Ag(tsac)(PPh3)3], bis(2,2Ј-bipyridine)bis-ꢀ2-S-(thio-
saccharinato)-disilver(I), [Ag2(tsac)2(bipy)2], and tris (trip-
henylphosphine)tetrakis-ꢀ3-S,N-(thiosaccharinato)-tetrasil-
ver(I), [Ag4(tsac)4(PPh3)3].
stant stirring, at room temperature. The solid was collected
by Wltration and washed with small amounts of diethyl
ether. Varying the stoichiometry of the reaction from a Ag/
PPh3 molar ratio 1:3 [Ag(tsac) 0.015 g (0.05 mmol)/ PPh3
0.039 g (0.15 mmol)] to 1:2 [Ag(tsac) 0.012 g (0.04 mmol)/
PPh3 0.021 g (0.08 mmol)] yielded the same solid. The com-
pound was recrystallized by slow evaporation of saturated
solutions of the complex in acetonitrile at room tempera-
ture. Yellow single crystals suitable for X-ray diVraction
study were formed during evaporation. The compound was
air and light-stable.
The same compound was also obtained as a microcystal-
line powder from the reaction of equimolar amounts of
[Ag(PPh3)4]BF4 (0.072 g, 0.060mmol) and thiosaccharine
(0.012g, 0.060mmol) dissolved in methanol–ethanol (3:1)
mixtures (16ml).
2.3. Synthesis of [Ag2(tsac)2(bipy)2] (3)
The complex was prepared by slow addition of a Htsac
solution (0.020 g, 0.10 mmol) in CH3CN to a AgNO3 solu-
tion (0.016 g, 0.10 mmol) in CH3CN containing also 2,2Ј-
bipyridine (0.016 g, 0.10 mmol). The resulting clear yellow
solution was kept in the darkness at room temperature
and a day later yellow crystals were formed. Yield: 55%.
Anal. Calcd. for C34H24N6O4S4Ag2 (%) C, 44.2; N, 9.1; H,
2.6; S, 13.9%. Found: C, 45.1; N, 8.8; H, 2.4; S, 13.8%. The
compound was air and light-stable. Some of the formed
crystals were of a quality suitable for single-crystal X-ray
diVraction study. Compound (3) was also obtained as yel-
low crystals by slow diVusion of CH2Cl2 in a solution con-
taining equimolar amounts of complex (1) (0.030 g,
0.10 mmol) and 2,2Ј-bipyridine (0.016 g, 0.10 mmol) in
DMSO.
S
-
C
N
tsac
S
O
O
2. Experimental
Attempts to obtain 4,4Ј-bipyridine derivates of Ag(tsac)
by using the appropriate stoichiometric amount of the N-
donor ligand were unsuccessful. The diamine favored the
dissolution of 1 but in the crystallization processes the last
complex being always recovered.
2.1. Materials and chemical analysis
Thiosaccharine (Htsac) was prepared by reaction of sac-
charine (Mallindkrodt) with Lawesson’s reagent (Fluka) in
toluene, according to the procedure described by Schibye
et al. [15]. Ag(tsac) (1) was prepared as a yellow solid by the
reaction of AgNO3and thiosaccharine in acetonitrile, in
molar ratio 1:1 (yield: 71%) and recrystallized in the same
solvent [7].
The white crystalline substance [Ag(PPh3)4]BF4 was
obtained by the addition of Ag(BF4) (Aldrich) to a concen-
trated solution of PPh3 in dried THF, in a Ag/PPh3 molar ratio
of 1:5. Solvents used in this work were of analytical grade and
dried by known procedures [16]. The percent elemental com-
position analyses were performed at INQUIMAE (Facultad
de Ciencias Exactas y Naturales, UBA, Argentina).
2.4. Synthesis of [Ag4(tsac)4(PPh3)3](4)
The new crystalline substance was prepared by the reac-
tion of (1) and PPh3 in acetonitrile in a molar ratio Ag/PPh3
1:1 (Ag(tsac) 0.024 g, 0.080mmol and PPh3 0.020 g,
0.080 mmol), in the presence of 4,4Ј-bipyridine (0.012 g,
0.080 mmol). The resulting clear solution was kept at room
temperature in the darkness for 24h, giving yellow single
crystals. After a few days, some of the crystals loose their
original quality. Then the results of several chemical analy-
ses not being reproducible.
2.5. Spectroscopic measurements
2.2. Synthesis of [Ag(tsac)(PPh3)3] (2)
Infrared spectra were recorded between 4000 and 400
cm¡1 on a Nicolet Nexus FTIR spectrophotometer using
the KBr pellet technique. Spectra obtained from suspensions
A pale yellow solid was obtained by slow addition of
complex (1) in a PPh3 solution in acetonitrile under con-

112
M. Dennehy et al. / Journal of Molecular Structure 841 (2007) 110–117
of the powdered samples in Nujol gave identical results.
The electronic absorption spectra of the solid state com-
plexes dispersed in KBr discs were recorded on a Cecil CE
2021 spectrophotometer in the range of 200–550nm. The
1H, 13C and 31P-NMR spectra of CDCl3 solutions, at 300 K,
were recorded on a Multinuclear Bruker ARX-300 equip-
ment.
hydrogen atom positions were calculated geometrically and
were included as riding on their respective carbon atoms.
Complex (3) was situated across a center of symmetry and
thus, only half of the molecule was resolved and reWned.
3. Results and discussion
3.1. FT-IR spectra
2.6. Crystal structure determinations
The solid state FT-IR spectra of the complexes provide
information regarding the coordination mode of the thi-
one ligand and conWrm the presence of the secondary
ligands. The most interesting bands to be analyzed are
those related to vibrations of the Wve membered ring of
the thiosaccharinate anion, located between 1500 and 400
cm¡1. There are no signiWcant diVerences for the bands
corresponding to vibrations of the thione benzenic ring
after coordination. The disappearance of the ꢁ(N–H)
band of the protonated thiosaccharine is conWrmed in
combination with the lack of ꢁ(SH) band at 2500-2600
cm¡1, indicating that the thione ligand is in the deproto-
nated form in these complexes [5a,18]. Table 2 reports the
IR vibrational assignments for the thiosaccharinate moie-
ties. Those assignments are based on the general informa-
Data were collected at room temperature (25°C) on a
Nonius Kappa-CCD area detector diVractometer with
COLLECT (Nonius B.V., 1997–2002). The unit cell param-
eters were calculated and reWned from the full data set.
Crystal cell reWnement and data reduction were carried out
using HKL2000 DENZO-SMN (Otwinowski and Minor,
1997). The absorption correction was applied using
HKL2000 DENZO-SMN (SCALEPACK). The crystal
data and reWnement parameters for the three complexes are
listed in Table 1.
The SHELXTL/PC V6.14 for Windows NT (Sheldrick,
G.M., 2001) [17] suite of programs was used to solve the
structure by direct methods. Subsequent diVerence Fourier
syntheses allowed the remaining atoms to be located. The
Table 1
Crystallographic data and structure reWnement for complexes [Ag(tsac)(PPh3)3] (2), [Ag2(tsac)2(bipy)2] (3) and [Ag4(tsac)4(PPh3)3] (4)
IdentiWcation code
(2)
(3)
(4)
Empirical formula
Formula weight
Temperature
C
61H49AgNO2P3S2
C34H24Ag2N6O4 S4
924.57
298(2) K
C82H61Ag4N4O8 P3S8
2011.22
301(2) K
1092.91
298(2) K
Wavelength
0.71073 Å
0.71073 Å
0.71073 Å
Crystal system
Space group
Orthorhombic
Pbca
Triclinic
P-1
Triclinic
P-1
Unit cell dimensions
a D 19.8680(3) Å
b D 20.4812(3) Å
c D 25.4391(3) Å
ꢂ D 90°
a D 8.189(2) Å
b D 8.887(2) Å
c D 12.313(4) Å
ꢂ D 88.40(2)°
a D 13.8042(12) Å
b D 15.9230(11) Å
c D 19.6305(18) Å
ꢂ D 84.422(5)°
ꢃ D 84.107(4)°
ꢄ D 89.343(4)°
4271.7(6) Å3
ꢃ D 90°
ꢃ D 80.24(2)°
ꢄ D 72.10(2)°
ꢄ D 90°
Volume
Z
Density (calcul.)
Abs. coeYcient
F(000)
Crystal size
Theta range for data collection
Index ranges
10351.7(2) Å3
8
840.1(4) Å3
1
2
1.403 Mg/m3
0.608 mm¡1
1.828 Mg/m3
1.564 Mg/m3
1.464 mm¡1
1.210 mm¡1
4496
460
2012
0.40 £ 0.38 £ 0.22 mm3
0.75 £ 0.15 £ 0.05 mm3
0.15 £ 0.13 £ 0.03 mm3
2.55–25.03°
2.90–25.02°
2.56–25.03°
¡23 6 h 6 23,
¡24 6 k 6 24,
¡30 6 l 6 30
95643
9 6 h 6 9,
¡16 6 h 6 13,
¡18 6 k 6 18,
¡23 6 l 6 23
35481
¡10 6 k 6 10,
¡10 6 l 6 14
4247
ReXections collected
Independent reXect.
9131 [R(int) D 0.062]
D 25.03° 99.8%
Semi-empirical from equivalents
0.8753 and 0.7929
Full-matrix least-squares on F2
9131/0/523
2675 [R(int) D 0.044]
D 25.02° 90.1%
Semi-empirical from equivalents
0.9304 and 0.4064
Full-matrix least-squares on F2
2675/0/226
14951 [R(int) D 0.095]
D 25.03° 99.1%
Semi-empirical from equivalents
0.9704 and 0.8393
Full-matrix least-squares on F2
14951/0/874
Completeness to theta
Absorption correction
Max. and min. transmission
ReWnement method
Data/restraints/parameters
Goodness-of-Wt on F2
Final R indices [I > 2sigma(I)]
R indices (all data)
1.023
1.057
0.992
R1 D 0.0399, wR2 D 0.0990
R1 D 0.0698, wR2 D 0.1135
0.470 and ¡0.942 e Å¡3
R1 D 0.0469, wR2 D 0.1178
R1 D 0.0707, wR2 D 0.1297
0.631 and ¡0.871 e Å¡3
R1 D 0.0760, wR2 D 0.1298
R1 D 0.2376, wR2 D 0.1751
0.575 and ¡0.588 e Å¡3
Largest diV. peak and hole

M. Dennehy et al. / Journal of Molecular Structure 841 (2007) 110–117
113
Table 2
indicates that the ligands strongly coordinate to the silver
atoms and there is only one species in the CDCl3 solution.
The existence of a broad singlet instead of the doublet or
doublet–doublet signals expected for a P-atom coordi-
nated to a silver nucleus, is presumed to be a consequence
of the existence of a rapid ligand-exchange equilibrium at
room temperature [25]. In the 13C-NMR spectra of com-
plex 2 the Wve signals centered at 120.44, 126.04, 135.45,
138.77 and 189.17 ppm can be assigned to carbon atoms
resonances of the thiosaccharinate ligands [5f]. The last
signal, corresponding to the thiocarbonilic carbon atoms,
is downWeld shifted from the free ligand, indicating that
the anions are coordinated to the silver centers in solution
[5f]. The PPh3-carbon signals lie in the range 128.7–134.5
ppm, mixed with the resting two resonances of the thio-
saccharinate anions.
FT-IR spectra assignment for the thiosaccharinate absorption bands of
complexes (1), (2), (3) and (4)
Assignments
(1)
(2)
(3)
(4)
ꢁ(CN), ꢁ(ꢂs)
ꢁas(SO2)
1440ma
1334vs
1170vs
1126m
1000vs
800s
628w
555m
540w
(1398)b
1296vs
1155s/ 1148s
1117m
1006m
814m
623w
553w
538vw
1411m
1302s
1159vs/1151vs
1123m
997s
795s
626m
553m
536m
(1435)b
1319s
1166vs
1123m
1003s
800m
626w
ꢁs(SO2), ꢁ(CC)
ꢁs(SO2), ꢅ(ꢆSN)
ꢁ(CS), ꢅ(CNS)
ꢁ(NS), ꢅ(CCC)
ꢄ(SO2), ꢅ(ꢆCN)
ꢅw(SO2), ꢅ(CS)
ꢄ(CCS)
555m
536w
a
vs, very strong; s, strong; m, medium; w, weak; vw, very weak.
Overlapped with neutral ligand bands.
b
tion analyzed and discussed in previous papers [5,19] and
on the theoretical calculations performed by I. Binev et al.
and G. Jovanovski et al. [20].
In the 1H-NMR spectra of the complex [Ag2(tsac)2(2,2Ј-
bipy)2] in CDCl3 solutions, the characteristic signals of the
2,2Ј-bipyridine ligands lie at 7.59 (mixed with a tsac- reso-
nance), 7.98 (dt,4H), 8.20 (dd,4H) and 8.80 (dd,4H) ppm.
The pattern of the signals and their chemical shifts indicate
the coordination of the bipyridines to the silver atoms [26].
Three of the thiosaccharinate-proton resonances are cen-
tered at 7.78 (m,1H), 7.90 (d,1H) and 8.11 (d,1H) and it can-
not be concluded if complex 3 is dimeric in solution or
changes to the mononuclear structure observed for other
[AgL(2,2Ј-bipy)] complexes [26].
In all the new compounds the stretching of the C–N
and C–Sexo (exo: exocyclic) bonds lie at greater and lower
frequencies, respectively, than for the “free” anion in
ammonium thiosaccharinate, (NH4)tsac [ꢁ(CN): 1340
cm¡1 and ꢁ(CS): 1014 cm¡1] [21] or potassium thiosaccha-
rinate, K(tsac) [ꢁ(CN): 1338 cm¡1 and ꢁ(CS): 1016 cm¡1]
[5e]. This is in accordance with anionic ligands coordi-
nated in the thiolato form in the solid complexes. The
possible participation of the nitrogen atom in the coordi-
nation is not clearly indicated by the IR data. The spectra
show the expected strong absorptions produced by the C-
H bonds and the skeletal vibrations of the coordinated
triphenylphosphine [22] and 2,2Ј-bipyridine [23] ligands.
For complexes (2) and (4) some thiosaccharinate absorp-
tions are masked by the strong bands of the PPh3.
To understand the eVect of the presence of 4,4Ј-bipyri-
dine in the synthesis of the [Ag4(tsac)4(PPh3)3] complex,
1
the H-NMR and 31P{1H}-NMR spectra of equimolar
mixtures of Ag(tsac) (1), triphenylphosphine and 4,4Ј-
bipyridine in CDCl3 solutions were obtained. Much of the
proton signals of the substances lie in the range between
7.3 and 7.8 ppm. In the mixture of resonances, a character-
istic doublet-doublet signal at 7.76 ppm can be assigned to
the H2,H2Ј protons of 4,4Ј-bipyridine. The other doublet-
doublet resonances of the H3,H3Ј protons appears at 8.96
ppm. Then, both bipyridine signals are downWeld shifted
from the free ligand (7.44 and 8.65 ppm). The appearance
of only two bipyridine signals, both downWeld shifted
indicates that in solution, 4,4Ј-bipyridine acts as a
bridge between silver atoms [27]. The 31P{1H} spectra of
the mixture in CDCl3 solutions show only a broad singlet
at 62.13 ppm and a very small signal at 79.91 ppm. Both
phosphorus resonances are downWeld shifted from the sig-
nals of PPh3 molecules in complex 2, a expected eVect
when the number of phosphines coordinated to the same
metal center diminished [28]. The observation of two
phosphorus signals indicates the existence of a mixture
of species in solution. Then, the 4,4Ј-bipyridine molecules
act as ligands in solution and the PPh3 molecules are
tightly bonded to the metal centers. But in the process
of crystallization of complex 4, the bipyridine ligand
leaves the silver coordination spheres. This phenomena
may be responsible for the asymmetry of the molecule,
with only three silver nuclei coordinated by PPh3
moieties.
3.2. Electronic and NMR spectra
The electronic absorption spectra of the solid com-
plexes (2) and (4) (KBr discs) show two intense bands at
220 and 270 nm, and a broad band with a maximum at
335–358 nm. The Wrst two bands can be attributed to the
ꢁ!ꢁ¤ transitions of the phenyl groups in the phosphine
ligands. The lower energy band lies in the spectral region
for the expected n!ꢁ¤ and ꢁ!ꢁ¤ (C–S) transitions in
thiosaccharine and other thiones [4d]. The electronic spec-
tra for complex (3) show three peaks at 203, 297 and
367 nm. The Wrst two corresponding to transitions of the
2,2Ј-bipy ligands and the later to the thionates [24].
1
In the H-NMR spectra of [Ag(tsac)(PPH3)3] complex,
the signals due to the triphenylphosphine molecules lie in
the range 7.07–7.34 ppm (m,46H), partially mixed with the
resonances of one of the protons of the thiosaccharinate
anion. Between 7.36 and 7.90 ppm, three of the thiosac-
charinate-proton signals appear, centered at 7.41(m,1H),
7.55 (d,1H) and 7.85 (d,1H), upWeld shifted from the corre-
sponding resonances of Pd(II) thiosaccharinate [5f]. In the
31P{1H} spectra of complex 2 only a broad singlet at 55.72
ppm is observed, downWeld shifted from the free ligand. It

114
M. Dennehy et al. / Journal of Molecular Structure 841 (2007) 110–117
3.3. Crystal structures
tetra coordinated silver atoms bonded to three phosphorus
atoms like Ag(PPh3)3I [d(Ag–P) D2.533, 2.559 and 2.681 Å]
[8a]. Shorter Ag–PPh3 bond lengths have been observed in
silver thiolates or thionates with only one or two phosphine
molecules bonded to the metal centers [8b,24,30,31]. The
deviations of the P–Ag–P angles from an ideal tetrahedral
geometry [112.58(3), 113.35(3) and 112.03(3)°] may be
attributed to steric interactions between the bulky PPh3
ligands and are in accordance with the observed diVerences
between Ag–P bond lengths.
3.3.1. Complex [Ag(tsac)(PPh3)3] (2)
X-ray structure analysis of complex (2) reveals that this
mononuclear compound crystallizes in the orthorhombic
space group Pbca, with eight molecules in the unit cell. A
selection of bond lengths and angles of the compound are
listed in Table 3 and a thermal ellipsoid plot of its structure
is shown in Fig. 1. Consideration of the angles around the
central metal atom indicate than the Ag cation is located in
the center of a distorted tetrahedron. The silver coordina-
tion sphere is formed by one S atom of a monocoordinated
thionate and three P atoms of triphenylphosphine mole-
cules. The Ag–S distance of 2.5939(10)Å, lies in the upper
side of the range for silver thiolate or thionate complexes
[10] and is very similar to the distances observed for
neutral thiones coordinated to silver atoms, such as
[Ag(PPh3)2 (py2SH)Cl] (Ag–S: 2.625Å) [13] or [Ag2(ꢀ-
dppen)3(pymtH)2](NO3)2 (Ag–S: 2.5660/2.5923 Å) [dppen:
bis(diphenylphosphine)ethene, HpymyH: pyrimidine-2-thi-
one] [29]. Notwithstanding the volume of the phosphines
forces the Ag–S bond to lengthen, the thiosaccharinate-sil-
ver interaction is strong enough to allow the replacement of
one PPh3 molecule from the [Ag(PPh3)4]+ cation, even in
the presence of an excess of the phosphine ligand. The three
Ag–P distances (2.522(8), 2.575(8) and 2.676(8) Å), are very
similar to the values found for other complexes containing
The thiosaccharine ligand changes its structure after
coordination. Upon deprotonation the thiocarbonile bond
of Htsac (CBS: 1.622Å) [18] becomes longer due to the
negative charge delocalization over the Sexo atom [19], i.e. to
a value of 1.666 Å in the ionic ammonium thiosaccharinate
[21]. In the silver complex the monocoordination of the
ligand through the exocyclic S atom makes the C2–S1 dis-
tance slightly longer (1.678(3) Å), although it is shorter than
other monocoordinated thiosaccharinates, like Cd(tsac)2·
H2O (1.7083Å) and Cd(tsac)2(bim)2 (1.7022/1.6965 Å)
[5a,5d]. This fact reXects the already discussed lengthening
+
of the Ag(I)–tsac interaction in the crowded Ag(PPh3)3
centers. It agrees as well with the IR positions of the bands
corresponding principally to the stretching vibration of the
C–Sexo bond, ꢁ(CS), which appears at 1016 cm¡1 in
NH4(tsac) and 1000 cm¡1 in Ag6(tsac)6 and in the middle of
the range, 1006 cm¡1, in Ag(tsac)(PPh3)3. The C–N bond
distances are also within the expected limits: C2–N3 bond
of 1.320(4) Å in complex (2) versus 1.312/1.314Å in
Cd(tsac)2(bim)2 [5d] and 1.334 Å in ammonium thiosaccha-
rinate [21]. This is in agreement with the relative IR stretch-
ing frequencies, ꢁ(CN), shown in Table 2.
Table 3
Selected bond lengths [Å] and angles [°] for [Ag(tsac)(PPh3)3] (2)
Ag–P2
Ag–P(1)
Ag–S(1)
P2–Ag–P1
P2–Ag–S1
P1–Ag–S1
P2–Ag–P3
2.5226(8)
2.5752(8)
2.5939(10)
112.58(3)
129.28(3)
94.01(3)
Ag–P3
S1–C2
C2–N3
P1–Ag–P3
S1–Ag–P3
C2–S1–Ag
2.6765(8)
1.678(3)
1.320(4)
112.03(3)
93.20(3)
124.68(12)
Finally, the nine independent P–C bond distances (aver-
aging 1.830 Å) are comparable to those observed in other
Ag–phosphine complexes reported in the literature [13].
113.35(3)
3.3.2. Complex [Ag2(tsac)2(bipy)2] (3)
Data for [Ag2(tsac)2(bipy)2] complex were consistent
with a triclinic space group P(¡1), with one molecule in the
unit cell. The full complex is a simple centrosymmetric
dinuclear molecule where the silver nuclei are held together
by a Ag–Ag bond and two Ag–S–Ag bridges, using the exo-
cyclic S atoms of the two thiosaccharinate anions. A ther-
mal ellipsoid representation of the molecular structure is
reported in Fig. 2. Selected bond length and angles of com-
plex (3) are listed in Table 4.
Complex (3) can be described as a Ag2S2 parallelogram
with the bipyridine molecules placed almost perpendicular
to the Wrst subunit (torsion angle AgЈ–S1–Ag–N11:
142.93(14)°). The Ag–S bond lengths (2.5770(19) and
2.6305(18) Å) lie in the range of other dimeric or polymeric
silver–thiol or –thione compounds, like [Ag(PPh3)
(bzimtH2) Br]2 (2.5548Å) [12] and [{Ag(py2SH)2}BF4]n
(2.555 and 2.680 Å) or [Ag(py2S)]n (2.424 and 2.647 Å)
where the Ag2S2 subunits polymerize as inWnite chains or
sheets [2c]. The metal-metal separation (Ag–AgЈ:
2.7884(12)Å) is shorter than the corresponding distance in
Fig. 1. ORTEP drawing of the molecular structure of [Ag(tsac)(PPh3)3]
(2) showing 50% probability ellipsoids. Hydrogen atoms and some
atom-labellings are omitted for clarity.

M. Dennehy et al. / Journal of Molecular Structure 841 (2007) 110–117
115
Finally, in complex (3) one can observe that there are no
signiWcant intermolecular packing interactions worth com-
menting on.
3.3.3. Complex [Ag4(tsac)4(PPh3)3] (4)
The crystal system for complex (4) was found to be tri-
clinic P(¡1), with a single molecule, and some voids in the
asymmetric unit. Selected bonds and angles for (4) are listed
in Tables 5 and 6, respectively. The molecular structure of
the complex is shown in Fig. 3. The metal center arrange-
ment inside the cluster do not conform to a regular polyhe-
dra, indeed it is partway between a tetrahedron and a
regular “butterXy” structure. Finer detail of the inner
molecular arrangement of the Ag, P, Sexo and N atoms is
reported in Fig. 4. The metal-metal distances are in the
range 2.952–4.349 Å, and only two distances, namely Ag1–
Ag2 and Ag1–Ag3, are considered weak silver-silver bonds
[33]. The four faces of the “tetrahedron” are capped by
thiosaccharinate ligands tri-coordinated in a ꢀ3-S,N (ꢀ2-S;
ꢀ1-N) six electron donor system. The apparently regular
structure becomes distorted by the presence of triphenyl-
phosphine ligands at only three of the four metal centers.
Silver atom Ag4 has a Xattened tetrahedral PS2N environ-
ment; Ag2 and Ag3 have similar asymmetric coordination
spheres conformed by a P atom, two Sexo atoms, one N
atom and the Ag1 metal center, while Ag1 is in the center of
a distorted trigonal bipyramid formed by two Sexo atoms,
one N atom and two silver centers (Ag2 and Ag3). As can
be expected, bond distances around Ag1 atom are shorter
than those observed for the triphenylphosphine bonded
atoms. Notwithstanding, all the inner cluster bond lengths
and the Ag–PPh3 distances are within the values observed
for other silver–thiolate and silver–thiolate–PPh3 com-
plexes [2c,3b,35b–38]. The chemistry of binary and ternary
silver-thiolate compounds shows a great variety of regular
or irregular metal-ligand polyhedric structures. When PPh3
is the third ligand, regular arrangements such as
(PPh3)2Ag4(MT)4 [11], or irregular structures, such as the
distorted “chair” in [Ag4(SPh)4(PPh3)4] [10] or the highly
distorted octahedron in the [Ag6(SC6H4Cl)6(PPh3)5] cluster
[35b], has also been observed.
Fig. 2. ORTEP drawing of the molecular structure of [Ag2(tsac)2(bipy)2]
(3) showing 50% probability ellipsoids. Hydrogen atoms are omitted for
clarity.
metallic silver (2.88 Å [32]), and it can be considered as an
eVective Ag–Ag bond following the criteria of P. Pyykkö
[33] and M. Jansen [34]. Although the closed d10 conWgura-
tion of Ag(I) appears to make any intermetallic bonding
between silver centers unnecessary [35a]. Very similar Ag–
Ag separations have been found for one of the bonds, the
shortest bond, in the polymeric [Ag(pyS)]n complex
(2.799 Å) [2c].
The thiosaccharinate anions can be considered as planar
species twisted with respect to the Ag2S2 unit by 98.70° and
not coplanar between them (interplanar distance is approx.
0.10 Å). The twisted positions together with the great value
of the S1–C1–N2 angle (125.5(4)°) put the endocyclic N
atoms too far apart for any Ag–N interaction (Ag,N3 dis-
tance is 3.492Å). The C–Sexo bond length (1.697Å) is longer
to the bond length found for the thiosaccharinate anion in
complex (2) (1.678(3) Å). This is in agreement with the
change from single bonded (ꢀ1-S) mode in complex (2) to
bridging (ꢀ2-S) in complex (3). Moreover, the C2–N3 bond
length (1.310(7)Å) is a little shorter than in complex (2).
Ag–N bonds in complex (3) (2.327(5) and 2.356(5) Å) are
little longer than in other Ag(I)-2,2Ј-bipyridine containing
complexes [14]. The two halves of 2,2Ј-bipyridine are quasi-
coplanar, showing a interplanar dihedral angle of 16.3°,
similar to the value 16.61° found for AgNO3:bpy [14].
The thiosaccharinate C–Sexo bond lengths are longer
than those observed in complex (3) showing a stronger
Table 5
Selected bond lengths [Å] for [Ag4(tsac)4(PPh3)3] (4)
Table 4
Ag1–Ag3
Ag1–Ag2
Ag1–N13
Ag1–S31
Ag1–S41
Ag2–N23
Ag2–P2
Ag2–S11
Ag2–S31
Ag3–N33
Ag3–P3
2.9521(12)
2.9998(11)
2.270(8)
2.427(3)
2.479(3)
2.313(9)
2.496(3)
2.618(3)
2.679(3)
2.331(8)
2.481(3)
2.595(3)
2.660(3)
Ag4–N43
Ag4–P4
2.311(8)
2.559(3)
2.582(3)
2.624(3)
1.717(11)
1.305(12)
1.732(10)
1.303(12)
1.689(10)
1.302(11)
1.718(12)
1.310(12)
Selected bond lengths [Å] and angles [°] for [Ag2(tsac)2(bipy)2] (3)
Ag4–S21
Ag4–S11
S11–C12
C12–N13
S21–C22
C22–N23
S31–C32
C32–N33
S41–C42
C42–N43
Ag–N11
Ag–N22
Ag–S1
Ag–S1#1
S1–Ag–S1#1
S1–Ag–Ag#1
S1#1–Ag–Ag#1
Ag–S1–Ag#1
N11–Ag–N22
N11–Ag–S1
N22–Ag–S1
2.327(5)
2.356(5)
2.5770(19)
2.6305(18)
115.26(5)
58.56(5)
56.70(4)
64.74(5)
70.66(17)
110.48(13)
125.97(13)
Ag–Ag#1
S1–C2
C2–N3
2.7884(12)
1.697(5)
1.310(7)
N11–Ag–S1#1
N22–Ag–S1#1
N11–Ag–Ag#1
N22–Ag–Ag#1
C2–S1–Ag
121.79(13)
106.34(12)
145.10(13)
143.92(12)
101.9(2)
Ag3–S21
Ag3–S41
C2–S1–Ag#1
N3–C2–S1
102.8(2)
125.5(4)

116
M. Dennehy et al. / Journal of Molecular Structure 841 (2007) 110–117
Table 6
Selected angles [°] for [Ag4(tsac)4(PPh3)3] (4)
Ag3–Ag1–Ag2
N13–Ag1–S31
N13–Ag1–S41
S31–Ag1–S41
N13–Ag1–Ag3
S31–Ag1–Ag3
S41–Ag1–Ag3
N13–Ag1–Ag2
S31–Ag1–Ag2
S41–Ag1–Ag2
N13–Ag1–Ag4
Ag2–Ag1–Ag4
S31–Ag1–Ag4
S41–Ag1–Ag4
Ag3–Ag1–Ag4
N23–Ag2–S31
P2–Ag2–S31
93.88(3)
119.2(2)
104.1(2)
131.89(10)
141.3(2)
94.05(7)
57.87(7)
88.5(2)
58.02(7)
147.82(8)
77.1(2)
70.86(3)
124.26(7)
83.08(8)
67.39(3)
98.7(2)
103.41(10)
122.78(9)
76.43(6)
122.4(2)
113.6(2)
97.36(10)
102.89(19)
131.85(8)
S31–Ag2–Ag1
N33–Ag3–S21
N33–Ag3–S41
S21–Ag3–S41
P3–Ag3–Ag1
S41–Ag3–Ag1
N33–Ag3–P3
P3–Ag3–S21
P3–Ag3–S41
N33–Ag3–Ag1
S21–Ag3–Ag1
N43–Ag4–S21
N43–Ag4–S11
P4–Ag4–S21
P4–Ag4–S11
N43–Ag4–P4
S21–Ag4–S11
N43–Ag4–Ag1
P4–Ag4–Ag1
S21–Ag4–Ag1
S11–Ag4–Ag1
N43–C42–S41
N33–C32–S31
N23–C22–S21
50.20(6)
103.80(19)
113.3(2)
123.38(10)
145.81(8)
52.11(6)
119.5(2)
103.51(10)
93.90(10)
77.9(2)
99.67(7)
119.9(2)
105.7(2)
95.10(10)
98.63(10)
116.1(2)
119.38(9)
69.8(2)
Fig. 4. ORTEP drawing of the metal centers and coordinated ligands
inner atoms in complex [Ag4(tsac)4(PPh3)3] (4) showing 50% probability
ellipsoids.
S11–Ag2–S31
S11–Ag2–Ag1
N23–Ag2–P2
N23–Ag2–S11
P2–Ag2–S11
168.37(7)
89.85(7)
69.81(7)
125.3(8)
124.2(9)
126.9(8)
coordination modes for the anion. When enough bulky P-
donor ligands are involved a mononuclear Ag(I) centered
complex results and monodentate S-donor thionate form is
observed. When N,N-donor ligands are present, a dinuclear
ꢀ2-S-thionate bridged complex can be produced. And when
P-donor atoms are not enough to Wll the coordination
sphere of the metal atoms then a ꢀ3-N,S polynuclear com-
plexes can be obtained.
N23–Ag2–Ag1
P2–Ag2–Ag1
5. Supplementary material
Additional crystallographic data sets for the structures are
available through the Cambridge Structural Data Base, as
supplementary publication reference number CCDC-615246
for complex (2), CCDC-615245 for complex (3) and CCDC-
615247 for complex (4). Copies of this information may be
obtained free of charge from the Director, CCDC, 12 Union
Road, Cambridge, CB2 1EZ, UK (fax: +44-1223-336-033;
e-mail: depositccdc.cam.ac.uk or www: http://www.ccdc.cam.
ac.uk).
Acknowledgements
Fig. 3. ORTEP drawing of the molecular structure of [Ag4(tsac)4(PPh3)3]
(4) showing 50% probability ellipsoids. Hydrogen atoms and some atom-
labellings are omitted for clarity.
We thank SGCyT-UNS for Wnancial support of Project
M24/Q10. We express our gratitude to the generous assis-
tance of Dr. Hugo de Lasa and his useful and stimulating
discussions. We thank also Dra. Sandra Mandolesi for the
register of NMR spectra and her helpful comments.
coordination of the anions, like in complex (1) with ꢀ3-S,N
(ꢀ2-S; ꢀ1-N) type thiosaccharinates. The voids observed in the
crystal structure are certainly large enough to house solvent
molecules, however no solvent was found. It is assumed that
the solvent was eliminated in transit and this also led to the
larger R-value than the other two compounds.
References
[1] (a) I.G. Dance, Polyhedron 5 (1986) 1037;
(b) B. Krebs, G. Henkel, Angew. Chem. Int. Ed. Engl. 30 (1991) 769;
(c) C. Housecroft, Coord. Chem. Rev. 115 (1992) 141;
(d) R.H. Holm, P. Kennepohl, E.I. Solomon, Chem. Rev. 96 (1996)
2239.
4. Conclusion
Three new ternary silver(I) thiosaccharinate complexes
were prepared and characterized showing three diVerent
[2] (a) M. Hong, W. Su, R. Cao, W. Zhang, W.T. Wong, J. Lu, Inorg.
Chem. 38 (1999) 600;

M. Dennehy et al. / Journal of Molecular Structure 841 (2007) 110–117
117
(b) M.C. Hong, Y.Z. Zhao, W.P. Su, R. Cao, M. Fujita, Z.Y. Zhou,
A.C.S. Chan, Angew. Chem. Int. Ed. Engl. 39 (2000) 2468;
(c) W. Su, M. Hong, J. Weng, Y. Liang, Y. Zhai, R. Cao, Z. Zhou,
A.S.C. Chan, Inorg. Chim. Acta 331 (2002) 8.
[17] G.M. Sheldrick, SHELXTL-01, Programs for Crystal Structural
Analysis, University of Göttingen, Germany, 2001.
[18] O. Grupbe, M. PenaviT, G. Jovanovski, J. Chem. Crystallog. 24 (1994)
581.
[3] (a) J.A. García-Vázquez, A. Souza-Pedrares, M. Carobel, J. Romero,
A. Souza, Polyhedron 24 (2005) 2043, and refs. therein;
(b) J.A. García-Vázquez, J. Romero, A. Souza-Pedrares, M. Louro, A.
Souza, J. Zubieta, J. Chem. Soc. Dalton Trans. (2000) 559.
[4] (a) E.S. Rapper, Coord. Chem. Rev. 153 (1996) 199;
(b) E.S. Rapper, Coord. Chem. Rev. 165 (1997) 475;
(c) J.A. García-Vázquez, J. Romero, A. Sousa, Coord. Chem. Rev.
193–195 (1999) 691;
[19] M.M. Branda, N.J. Castellani, S.H. Tarulli, O.V. Quinzani, E.J. Baran,
R.H. Contreras, Int. J. Quant. Chem. 89 (2002) 525.
[20] (a) Y.I. Binev, C. Petkov, L. Pejov, Spectrochim. Acta Part A 56
(2000) 1949;
(b) G. Jovanovski, A. Cahil, O. Grupbe, L. Pejov, J. Mol. Struct. 784
(2006) 7.
[21] E.J. Baran, O.E. Piro, J. Zinczuk, Z. Anorg. Allg. Chem. 632 (2006)
437.
(d) P.D. Akrivos, Coord. Chem. Rev. 181–210 (2001) 213.
[5] (a) S.H. Tarulli, O.V. Quinzani, O.E. Piro, E.J. Baran, E.E. Castellano,
Monats. Chem. 132 (2001) 779;
[22] (a) R.J.H. Clark, C.D. Flint, A.J. Hempleman, Spectrochim. Acta Part
A 43 (1987) 805;
(b) R. Pilk, F. Duschek, C. Fickert, R. Finsterer, W. Kiefer, Vibrat.
Spectrosc. 14 (1997) 189.
(b) S.H. Tarulli, O.V. Quinzani, O.E. Piro, E.J. Baran, Z. Anorg. Allg.
Chem. 628 (2002) 751;
(c) S.H. Tarulli, O.V. Quinzani, O.E. Piro, E.J. Baran, J. Mol. Struct.
656 (2003) 161;
(d) S.H. Tarulli, O.V. Quinzani, O.E. Piro, E.E. Castellano, E.J. Baran.
J. Mol. Struct. 797 (2006) 56 (accesible on-line).;
(e) S.H. Tarulli, O.V. Quinzani, O.E. Piro, E.E. Castellano, E.J. Baran,
Z. Anorg Allg. Chem. 629 (2003) 1975;
[23] R.G. Inskeep, J. Inorg. Nucl. Chem. 24 (1962) 763.
[24] C. Kutal, Coord. Chem. Rev. 99 (1990) 213.
[25] E.L. Muetterties, C.W. Alegranti, J. Amer. Chem. Soc. 94 (1972) 6386.
[26] I. Beloso, J. Castro, J.A. García-Vázquez, P. Pérez-Lourido, J.
Romero, A. Souza, Inorg. Chem. 44 (2005) 336.
[27] A. Vertova, I. Cucchi, P. Fermo, F. Porta, D.M. Proserpio, S. Rondi-
nini, Electrochim. Acta (2006), doi:10.1016/j.electacta.2006.09.035.
[28] (a) C. Pettinari, Polyhedron 20 (2001) 2755;
(b) Z. Yuan, N.H. Dryden, J.J. Vittal, R.J. Puddephatt, Chem. Mater.
7 (1995) 1696.
(f) M. Vieytes, D. Gambino, M. González, H. Cerecetto, S.H. Tarulli,
O.V. Quinzani, E.J. Baran, J. Coord. Chem. 59 (2006) 102.
[6] E.J. Baran, V.T. Yilmaz, Coord. Chem. Rev. 250 (2006) 1980.
[7] G.P. Tellería, M. Dennehy, S.H. Tarulli, O.V. Quinzani, G. Echeverría,
O.E. Piro, E.E. Castellano, in preparation.
[29] P. Aslanidis, S. Divanidis, P.J. Cox, P. Karagiannidis, Polyhedron 24
(2005) 853.
[8] (a) A. Cassel, Acta Cryst. B 37 (1981) 229;
[30] D. Coucouvanis, N.C. Benzinger, S.M. Johnson, Inorg. Chem. 13
(1974) 1191.
[31] D.D. Heindrich, J.P. Fackler Jr., P. Lahuerta, Inorg. Chim. Acta 116
(1986) 15.
[32] N.B.N. Greewood, A. Earnshaw, Chemistry of the Elements, Perg-
amon, Oxford, UK, 1989, p. 1368.
(b) D.E. Hibbs, M.B. Hursthouse, K.M.A. Malik, M.A. Beckett, P.W.
Jones, Acta Cryst. C 52 (1996) 884.
[9] M.I. Bruce, D.N. DuVy, Aust. J. Chem. 39 (10) 1691.
[10] L.S. Ahmed, J.R. Dilworth, J.R. Miller, N. Wheatley, Inorg. Chim.
Acta 278 (1998) 229.
[11] C. López, J.P. Fackler, R. Staples, S. Wang, R. Winpenny, Croat.
Chem. Acta 68 (1995) 793.
[12] P.J. Cox, P. Aslanidis, P. Karagiannidis, S. Hadjikakou, Inorg. Chim.
Acta 310 (2000) 268.
[33] P. Pyykkö, Chem. Rev. 97 (1997) 597.
[34] M. Jansen, Angew. Chem. Int. Ed. 26 (1987) 1098.
[35] (a) I.G. Dance, L.J. Fitzpatrick, A.D. Rae, M.L. Scudder, Inorg. Chem.
22 (1983) 3785;
[13] P. Karagiannidis, P. Aslanidis, S. Kokkou, C.J. Cheer, Inorg. Chim.
Acta 172 (1990) 247.
(b) I.G. Dance, L.J. Fitzpatrick, D.C. Craig, M.L. Scudder, Inorg.
Chem. 28 (1989) 1853.
[14] G.A. Bowmaker, A. EVendy, S. Marfuah, B.W. Skeleton, A.H. White,
Inorg. Chim. Acta 358 (2005) 4371.
[15] S. Schibye, R.S. Pedersen, S.O. Lawesson, Bull. Soc. Chim. Belges 87
(1978) 229.
[16] A. Vogel, Textbook of Practical Organic Chemistry, Longman Group
Limited, London, 1978.
[36] M. Shi, J.K. Jiang, Chirality 15 (2003) 605.
[37] R. Noguchi, A. Mara, A. Sugie, K. Nomiya, Inorg. Chim. Acta 278
(1998) 229.
[38] P.C. Zachariadis, S.K. Hadjikakou, N. Hadjiliadis, A. Michaelides,
S. Skoulika, Y. Ming, Y. Xiaolin, Inorg. Chim. Acta 343 (2003)
361.