A new polymorph of (O-ethyl dithiocarbonato-κ2 S,S′)bis(triphenyl-phosphine-κP)silver(I)

Article abstract of DOI:10.1107/S0108270103003445

A new triclinic polymorphic modification of the title compound, [Ag(C₃H₅OS₂)(C₁₈ H₁₅P)₂], has been found and compared with the previously known orthorhombic modification [Tiekink (1988). Coord. Chem. 17, 239-243]. The two polymorphs have the same molecular shape, viz. a distorted tetrahedral geometry, with a chelating dithiocarbonate (xanthate) and two PPh₃ ligands bonded to the Ag atom. However, in this new polymorph, the xanthate ligand is bonded asymmetrically to the Ag atom, with Ag-S distances of 2.5489 (6) and 2.8055 (7) A, while for the orthorhombic polymorph these distances are 2.686 (4) and 2.601 (4) A The Ag-P distances are similar in both structures.

Full text of DOI:10.1107/S0108270103003445

metal-organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
the crystal structure was determined later (Tiekink, 1988). The
complex crystallizes in the orthorhombic system, with the Ag
atom in a distorted tetrahedral environment formed by two S
atoms of the chelating S2COEt ligand and by two PPh3 groups;
this geometry is similar to that of [Cu(S2COEt)(PPh3)2]
(Bianchini et al., 1985). The AgÐP distances [2.4193 (6) and
ISSN 0108-2701
Ê
A new polymorph of (O-ethyl
dithiocarbonato-j2S,S0)bis(triphenyl-
phosphine-jP)silver(I)
2.4614 (6) A] are very similar and lie in the range expected for
Ê
AgÐPPh3 bonds (2.363±2.529 A). The AgÐS distances are
Ê
also similar [2.686 (4) and 2.601 (4) A], although they are a
little longer than the distances found in other comparable Ag
È
coordination compounds (Muller et al., 1979). The S1ÐAg1Ð
S2 and P1ÐAg1ÐP2 planes are almost perpendicular
(89.81ꢀ).
Irene Ara,a* Fatima El Bahij,a² Mohamed Lachkarb and
Najib Ben Larbib
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
We report here a new polymorph of [Ag(S2COEt)(PPh3)2],
(I), that crystallizes in the triclinic system. The triclinic poly-
morph has the same general molecular shape (Fig. 1) as the
orthorhombic polymorph, i.e. the Ag atom has a distorted
tetrahedral environment, the distortion being due in part to
the restricted bite angle of the chelating xanthate ligand
[67.345 (19)ꢀ]. The AgÐP distances (Table 1) are comparable
in both cases. The main difference between the two poly-
morphs is that (I) features an asymmetrically chelating
xanthate ligand. The Ag1ÐS1 distance is longer than most
AgÐS bonds, although similar values have been found in
other complexes (Drew et al., 1987). This difference cannot be
attributed to packing forces. The bite distance of the xanthate
Received 27 January 2003
Accepted 11 February 2003
Online 28 February 2003
A new triclinic polymorphic modi®cation of the title
compound, [Ag(C3H5OS2)(C18H15P)2], has been found and
compared with the previously known orthorhombic modi®ca-
tion [Tiekink (1988). Coord. Chem. 17, 239±243]. The two
polymorphs have the same molecular shape, viz. a distorted
tetrahedral geometry, with a chelating dithiocarbonate
(xanthate) and two PPh3 ligands bonded to the Ag atom.
However, in this new polymorph, the xanthate ligand is
bonded asymmetrically to the Ag atom, with AgÐS distances
Ê
of 2.5489 (6) and 2.8055 (7) A, while for the orthorhombic
Ê
polymorph these distances are 2.686 (4) and 2.601 (4) A. The
AgÐP distances are similar in both structures.
Comment
In recent years, there has been a growing interest in the
preparation and study of polymorphs, not only because they
are intrinsically interesting phenomena that involve diverse
scienti®c branches (for example, mineralogy, materials science,
supramolecular chemistry and thermodynamics), but also
because polymorphism has become a major issue in the
pharmaceutical, optoelectronic, and dyes and pigments indus-
tries.
The addition of various ligands to suspensions of polymeric
metal xanthates (dithiocarbonates) often results in the
formation of monomeric adducts of different stoichiometries
and structures. For instance, [Cu(S2COEt)(PPh3)2] is four-
coordinated with a chelating xanthate ligand (Bianchini et al.,
1985), [Hg(S2COEt)2(PPh3)] is ®ve-coordinated (Watanabe,
1981), and the linear system [Au(S2COMe)(PPh3)] features a
monodentate xanthate ligand (Tiekink, 1985). [Ag(S2COEt)-
(PPh3)2] was ®rst prepared by the addition of PPh3 to a
suspension of Ag(S2COEt) (Kowala & Swan, 1966), although
Figure 1
The structure of (I), showing displacement ellipsoids at the 50%
probability level and the atom-numbering scheme. H atoms have been
omitted for clarity.
Â
² On leave from the Universite Sidi Mohamed Ben Abdellah, Morocco.
Acta Cryst. (2003). C59, m107±m108
DOI: 10.1107/S0108270103003445
# 2003 International Union of Crystallography m107

metal-organic compounds
Ê
Table 1
Selected geometric parameters (A, ).
is 2.9764 (9) A, and the angle between the S1ÐAg1ÐS2 and
ꢀ
Ê
P1ÐAg1ÐP2 planes is 75.55 (2)ꢀ. Thus, the coordination
sphere of the Ag atom in (I) is highly irregular, with a wide
variation in bond lengths and angles. There are also some
differences in the orientations of the phenyl groups between
the two forms. The dihedral angles between the P1ÐAg1ÐP2
plane and the planes of the phenyl rings bonded to P1 and P2
are 86.96 (6), 54.51 (6), 20.76 (8), 53.84 (5), 79.96 (6) and
47.38 (6)ꢀ, respectively, in (I). These angles are 69.39, 79.38,
38.47, 31.08, 59.22 and 74.79ꢀ for the orthorhombic poly-
morph.
Ag1ÐP1
Ag1ÐP2
Ag1ÐS2
Ag1ÐS1
2.4196 (7)
2.4612 (7)
2.5489 (6)
2.8055 (7)
S1ÐC1
S2ÐC1
O1ÐC1
1.680 (2)
1.693 (3)
1.347 (3)
P1ÐAg1ÐP2
P1ÐAg1ÐS2
P2ÐAg1ÐS2
P1ÐAg1ÐS1
P2ÐAg1ÐS1
S2ÐAg1ÐS1
123.04 (2)
118.85 (2)
113.08 (2)
125.71 (2)
94.25 (2)
C1ÐS1ÐAg1
C1ÐS2ÐAg1
O1ÐC1ÐS1
O1ÐC1ÐS2
S1ÐC1ÐS2
80.29 (9)
88.26 (9)
122.45 (18)
113.66 (17)
123.87 (15)
67.345 (19)
There is no clear evidence of intermolecular hydrogen
bonding; the shortest potential hydrogen-bond interaction
involves atoms C8 and S2 (Table 2). This contact could be
considered a weak electrostatic interaction, since the
Table 2
Short intermolecular contacts (A, ).
ꢀ
Ê
Ê
Ê
separation is 0.3 A shorter than the sum of the van der Waals
Ê
radii for H (1.2 A) and S (1.85 A) (Whuler et al., 1980). In
addition, there is weak intramolecular interaction
DÐHÁ Á ÁA
DÐH
HÁ Á ÁA
DÁ Á ÁA
DÐHÁ Á ÁA
a
C8ÐH8Á Á ÁS2i
0.95
0.95
2.76
2.79
3.568 (3)
3.632 (3)
144
148
Ê
C13ÐH13Á Á ÁS2ii
(S1Á Á ÁH2A = 2.76 A) that may be associated with the long
Ag1ÐS1 distance.
Symmetry codes: (i) 1 ‡ x; y; z; (ii) x; 1 y; z.
Experimental
Compound (I) was obtained from the reaction of [Zn(S2COEt)2]
(0.200 g, 0.651 mmol) with AgClPPh3 (0.528 g, 1.302 mmol) in di-
chloromethane (20 ml) at room temperature. After 30 min, the solid
product [a mixture of Ag(S2COEt) and ZnCl2] was ®ltered off and
the ®ltrate evaporated to dryness. The addition of isopropyl alcohol
to the residue gave (I) as a white solid (yield = 66%). Analysis,
calculated for C39H35AgOP2S2: C 62.17, N 4.64, S 8.49%; found: C
61.90, N 4.54, S 8.59%. Single crystals were obtained by slow diffusion
of n-hexane into a dichloromethane solution of (I) at room
temperature.
H atoms were treated as riding, with CÐH distances of 0.95
Ê
(aromatic), 0.98 (CH3) and 0.99 A (CH2).
Data collection: SMART (Bruker, 2000); cell re®nement: SAINT-
Plus (Bruker, 1999); data reduction: SAINT-Plus; program(s) used to
solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to
re®ne structure: SHELXL97 (Sheldrick, 1997); molecular graphics:
SHELXTL (Bruker, 2000); software used to prepare material for
publication: SHELXTL.
Â
We thank the Ministerio de Ciencia y Tecnologõa, Spain
(project No. BQU2002-03997-CO2-02), for ®nancial support.
Crystal data
[Ag(C3H5OS2)(C18H15P)2]
Mr = 753.60
Triclinic, P1
Z = 2
Dx = 1.454 Mg m
Mo Kꢀ radiation
3
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: JZ1546). Services for accessing these data are
described at the back of the journal.
Ê
a = 10.3302 (6) A
Cell parameters from 4690
re¯ections
Ê
b = 12.8582 (7) A
c = 13.8270 (8) A
ꢃ = 2.3±26.4ꢀ
ꢄ = 0.83 mm
T = 100 (2) K
Ê
1
ꢀ = 87.432 (1)ꢀ
ꢁ = 74.956 (1)ꢀ
ꢂ = 76.067 (1)ꢀ
Prism, pale yellow
0.25 Â 0.18 Â 0.16 mm
3
Ê
References
V = 1721.17 (17) A
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Inorg. Chem. 24, 932±939.
Bruker (1999). SAINT-Plus. Version 6.02. Bruker AXS Inc., Madison,
Wisconsin, USA.
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Bruker SMART APEX CCD
diffractometer
! scans
Absorption correction: multi-scan
(SADABS; Bruker, 1999)
Tmin = 0.819, Tmax = 0.879
10 445 measured re¯ections
6873 independent re¯ections
5720 re¯ections with I > 2ꢅ(I)
Rint = 0.019
ꢃ
max = 26.4ꢀ
h = 12 ! 12
k = 16 ! 10
l = 17 ! 17
È
È
È
Muller, A., Bogge, H. & Koniger-Ahlborn, E. (1979). Z. Naturforsch. Teil B,
Re®nement
34, 1698±1703.
Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of
Re®nement on F2
R[F2 > 2ꢅ(F2)] = 0.032
wR(F2) = 0.067
S = 0.94
6873 re¯ections
406 parameters
H-atom parameters constrained
w = 1/[ꢅ2(F2o) + (0.0289P)2]
where P = (F2o + 2Fc2)/3
(Á/ꢅ)max = 0.001
È
Gottingen, Germany.
Tiekink, E. R. T. (1985). Z. Kristallogr. 173, 243±244.
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Watanabe, Y. (1981). Acta Cryst. B37, 553±556.
3
Ê
Áꢆmax = 0.79 e A
3
Ê
0.49 e A
Whuler, A., Brouty, C. & Spinat, P. (1980). Acta Cryst. B36, 1267±1269.
Áꢆmin
=
ꢁ
m108 Irene Ara et al. [Ag(C3H5OS2)(C18H15P)2]
Acta Cryst. (2003). C59, m107±m108