Polymeric (O-ethyl dithiocarbonato)-silver(I)

Article abstract of DOI:10.1107/S0108270103010175

The title compound, [Ag(C₃H₅OS₂)]_n, is polymeric in the solid state and adopts a layered structure in which each Ag atom is five-coordinated in a distorted trigonal-bipyramidal geometry defined by four S atoms belonging to four different xanthate groups and by a neigbouring Ag atom [Ag...Ag = 3.0540 (8) A]. Each S atom is three-coordinated to one C and two Ag atoms. The structure can be envisaged as being formed by Ag₂(S₂COEt)₂ units in which every S atom is bonded to another Ag atom from a different unit and the Ag atoms are also bonded to two different S atoms of two other units. The result is a two-dimensional network of condensed metallacycles of six or eight atoms.

Full text of DOI:10.1107/S0108270103010175

metal-organic compounds
Acta Crystallographica Section C
Crystal Structure
atoms are coordinated to four S atoms, with distances ranging
Ê
from 2.51 to 2.74 A. In addition, there are two short metal±
Communications
metal distances per six Ag atoms. By contrast, the crystal
structures of the silver(I) xanthates, [Ag(S2COR)] (Kowala &
Swan, 1966), have not been determined to date because of the
dif®culty in obtaining suitable crystals. Silver xantates can
react easily, in spite of their low solubility, and when different
ligands are added to suspensions of polymeric silver xanthates,
monomeric soluble adducts, whose structures are well known,
can be obtained. An example of one of these adducts is
[Ag(S2COEt)(PPh3)2], of which two polymorphic modi®ca-
tions have been described (Tiekink, 1988; Ara et al., 2003).
We obtained crystals of [Ag(S2COEt)], (I), from the reac-
tion of [Zn(S2COEt)2] and O3ClOAgPPh3, in which the
[Ag(PPh3)4](ClO4) complex (Cotton & Goodgame, 1960;
Engelhardt et al., 1985) is the main product, and we studied the
structure of (I) in order to determine the nature of the
Ag-atom geometry and the mode of coordination of the
xanthate ligand.
ISSN 0108-2701
Polymeric (O-ethyl dithiocarbonato)-
silver(I)
Irene Ara,a* Fatima El Bahija² and Mohamed Lachkarb
a
Â
Â
Â
Departamento de Quõmica Inorganica, Instituto de Ciencia de Materiales de Aragon,
b
Â
Universidad de Zaragoza±CSIC, 50009 Zaragoza, Spain, and Departement de
Â
Â
Chimie, Faculte des Sciences Dhar-Mehraz, Universite Sidi Mohamed Ben Abdellah,
BP 1796 (Atlas), 30000 Fes, Morocco
Correspondence e-mail: irene.ara@posta.unizar.es
Received 10 April 2003
Accepted 9 May 2003
Online 11 June 2003
The title compound, [Ag(C3H5OS2)]n, is polymeric in the solid
state and adopts a layered structure in which each Ag atom is
®ve-coordinated in a distorted trigonal-bipyramidal geometry
de®ned by four S atoms belonging to four different xanthate
groups and by
a
neigbouring Ag atom [AgÁ Á ÁAg =
Ê
3.0540 (8) A]. Each S atom is three-coordinated to one C
and two Ag atoms. The structure can be envisaged as being
formed by Ag2(S2COEt)2 units in which every S atom is
bonded to another Ag atom from a different unit and the Ag
atoms are also bonded to two different S atoms of two other
units. The result is a two-dimensional network of condensed
metallacycles of six or eight atoms.
The structure of (I) consists of a two-dimensional polymeric
array of molecules (Fig. 1). All Ag atoms in each layer have
the same environment, viz. a distorted trigonal bipyramid, in
Comment
Silver thiolates have been known for some time, and their low
solubility suggests they are polymeric in nature. This fact has
been con®rmed, in the case of silver(I) complexes of dithio-
carbamates, by the determination of the crystal structures of
[Ag(S2CNR2)] (R = Et and n-Pr). The ꢀ forms of [Ag-
(S2CNEt2)] (Yamaguchi et al., 1976) and [Ag(S2CNPr2)]
(Hesse & Nilson, 1969) contain discrete hexameric molecules
in which the Ag atoms form a distorted octahedron with six
comparatively short and six longer edges. The short edges
correspond to metal±metal distances comparable to those in
the metallic phase of silver. All Ag atoms are connected to ®ve
atoms, viz. two Ag and three S atoms, while the S atoms are
bonded to one or two Ag atoms. In these hexameric units, the
terminal Ag atom in one molecule is bridged by an S atom to
Ê
that in the adjacent hexamer (AgÐS = 2.99 A), thus forming a
chain structure. The ꢁ modi®cation of [Ag(S2CNEt2)]
(Anacker-Eickhoff et al., 1982) is a true high polymer, in which
the Ag atom and the ligands are linked into chains. All the Ag
Figure 1
Packing diagram of (I), viewed along the c axis.
Â
² On leave from the Universite Sidi Mohamed Ben Abdellah, BP 1796 (Atlas),
30000 Fes, Morocco.
Acta Cryst. (2003). C59, m265±m267
DOI: 10.1107/S0108270103010175
# 2003 International Union of Crystallography m265

metal-organic compounds
six atoms (two Ag, three S and one C atom). Thus, the whole
array consists of non-planar fused metallacycles of six and
eight atoms, in which all atoms belong to both types of cycle.
Experimental
[Zn(S2COEt)2] (0.1 g, 0.325 mmol) and O3ClOAgPPh3 (0.471 g,
1.302 mmol) were mixed in dichloromethane (20 ml). After 15 min,
the resulting yellow solid was removed by ®ltration. The solution was
evaporated to ꢂ5 ml, and a layer of n-hexane was added carefully
and allowed to diffuse through the solution. After one week, a
mixture of yellow crystals of (I) and colourless crystals of
[Ag(PPh3)4](ClO4) was obtained, and the crystals were separated by
hand. [Ag(PPh3)4](ClO4) was identi®ed on the basis of its IR spec-
trum (Cotton & Goodgame, 1960) and elemental analyses (calculated
for C72H60AgClO4P4: C 68.82, H 4.77%; found: C 68.54, H 4.62%).
Figure 2
A view of the structure of the Ag2(S2COEt)2 moieties of (I), showing the
coordination geometry and the atom-numbering scheme. Displacement
ellipsoids are drawn at the 50% probability level and H atoms are shown
as small spheres of arbitrary radii. [Symmetry code: (i) 1 x, y, 1 z.]
Crystal data
3
[Ag(C3H5OS2)]
Mr = 229.06
Monoclinic, P21=c
Ê
a = 12.6929 (12) A
b = 6.1566 (6) A
c = 7.8385 (7) A
ꢁ = 104.419 (2)ꢁ
V = 593.25 (10) A
Z = 4
Dx = 2.565 Mg m
Mo Kꢀ radiation
Cell parameters from 1495
re¯ections
ꢂ = 3.3±26.3ꢁ
ꢃ = 3.97 mm
T = 100 (2) K
Ê
Ê
1
which the three S atoms are located in equatorial (eq) posi-
tions, and the axial (ax) positions are occupied by an S and an
Ag atom. The SÐAgÐS angles in the trigonal plane range
from 109.40 (3) to 124.38 (5)ꢁ, the SeqÐAgÐAg angles range
from 75.73 (4) to 98.08 (4)ꢁ, the SeqÐAgÐSax angles range
from 84.41 (4) to 105.36 (5)ꢁ and the AgÐAgÐSax angle is
168.43 (4)ꢁ. The AgÐSeq distances are very similar and range
3
Ê
Thin plate, yellow
0.36 Â 0.18 Â 0.02 mm
Data collection
Bruker SMART APEX CCD
diffractometer
! scans
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
Tmin = 0.329, Tmax = 0.925
3390 measured re¯ections
1211 independent re¯ections
1042 re¯ections with I > 2ꢄ(I)
Rint = 0.032
Ê
from 2.5073 (15) to 2.5578 (14) A. By contrast, the AgÐSax
Ê
ꢂmax = 26.4ꢁ
distance is signi®cantly longer [2.8379 (14) A]. The AgÁ Á ÁAg
h = 15 ! 11
Ê
distance of 3.0540 (8) A is long enough to postulate only a
k = 7 ! 7
l = 9 ! 9
weak interaction between the two metal atoms (Wang & Mak,
2001). In addition to this weak interaction, both Ag atoms are
bonded by a bridging xanthate ligand in which the S1Á Á ÁS2
Re®nement
Ê
Re®nement on F2
R[F2 > 2ꢄ(F2)] = 0.039
wR(F2) = 0.092
S = 1.03
1211 re¯ections
64 parameters
H-atom parameters constrained
w = 1/[ꢄ2(F2o) + (0.0546P)2]
where P = (F2o + 2Fc2)/3
(Á/ꢄ)max < 0.001
distance of 3.0201 (19) A is somewhat longer than the bite
distance shown by chelating xanthate ligands (Chan et al.,
1982). All the S atoms in the structure are three-coordinated
(to two Ag atoms and one C atom), thus forming a distorted
non-planar trigonal environment, with the S atoms lying above
3
Ê
Áꢅmax = 2.08 e A
3
Ê
1.25 e A
Áꢅmin
=
Ê
or below the coordination plane (0.8520 and 0.7701 A for S1
Table 1
Selected geometric parameters (A, ).
and S2, respectively). The xanthate ligand can be considered
as a tetradentate group, since each S atom is bonded to two
different Ag atoms. The bonding mode within the xanthate
ligand can be represented by the valence-bond formalism
shown in the Scheme below (Coucouvanis, 1970). In general,
resonance forms (a) and (b) best describe the structures of
xanthate complexes, but in (I), the short C1ÐO and long SÐ
C1 distances (Table 1) suggest that the contribution of reso-
nance structure (c) is not negligible. The structure is best
envisaged as being formed by units of two Ag atoms bridged
by two xanthate ligands (Fig. 2). If the AgÁ Á ÁAg interaction is
disregarded, these units form cycles of eight atoms (two Ag,
four S and two C atoms). Each S atom is also bonded to
another Ag atom from a different unit, thus forming a cycle of
ꢁ
Ê
AgÐS1
2.5073 (15)
2.5302 (15)
2.5578 (14)
2.8379 (14)
3.0540 (8)
S1ÐC1
S2ÐC1
OÐC1
OÐC2
C2ÐC3
1.701 (5)
1.710 (5)
1.318 (6)
1.462 (6)
1.504 (8)
AgÐS2i
AgÐS2ii
AgÐS1iii
AgÁ Á ÁAgi
S1ÐAgÐS2i
S1ÐAgÐS2ii
S2iÐAgÐS2ii
S1ÐAgÐS1iii
S2iÐAgÐS1iii
S2iiÐAgÐS1iii
S1ÐAgÁ Á ÁAgi
124.16 (5)
124.38 (5)
109.40 (3)
105.36 (5)
92.76 (4)
84.41 (4)
82.64 (4)
S2iÐAgÁ Á ÁAgi
S2iiÐAgÁ Á ÁAgi
S1iiiÐAgÁ Á ÁAgi
AgÐS1ÐAgiv
AgiÐS2ÐAgv
S1ÐC1ÐS2
75.73 (4)
98.08 (4)
168.43 (4)
105.06 (5)
112.63 (5)
124.6 (3)
1
2
1
2
1
2
Symmetry codes: (i)
x; 12 y; 12 ‡ z; (v) x;
1
x; y; 1 z; (ii) x;
y; 12 ‡ z.
y; z
;
(iii) x; 12 y; z
;
(iv)
1
2
ꢀ
m266 Ara, El Bahij and Lachkar
[Ag(C3H5OS2)]
Acta Cryst. (2003). C59, m265±m267

metal-organic compounds
The ®nal electron-density difference map showed four peaks
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3
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Â
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Supplementary data for this paper are available from the IUCr electronic
archives (Reference: TR1062). Services for accessing these data are
described at the back of the journal.
ꢀ
Acta Cryst. (2003). C59, m265±m267
Ara, El Bahij and Lachkar [Ag(C3H5OS2)] m267