Di-l-pyridine-2-thiolato-bis [ chloro ( triphenylphosphine ) copper ( I ) ]

# 2006 International Union of Crystallography All rights reserved The structure of the title compound, [Cu2(C5H5NS)2Cl2(C18H15P)2], shows two independent molecules, each a dimer bridged through a Cu2S2 rectangular plane involving the two pyridinethione S atoms and lying about a centre of symmetry. The Cu atoms have a distorted tetrahedral geometry. There is intramolecular hydrogen bonding between the pyridinium H atoms and the Cl ligands.

The structure of the title compound, [Cu 2 (C 5 H 5 NS) 2 Cl 2 -(C 18 H 15 P) 2 ], shows two independent molecules, each a dimer bridged through a Cu 2 S 2 rectangular plane involving the two pyridinethione S atoms and lying about a centre of symmetry. The Cu atoms have a distorted tetrahedral geometry. There is intramolecular hydrogen bonding between the pyridinium H atoms and the Cl ligands.

Comment
The dimeric title compound, [{CuCl(S{C 5 H 5 N})(P{C 6 H 5 } 3 )} 2 ], or [{CuCl(S{C 5 H 5 N})(PPh 3 )} 2 ], (I), has two half-molecules per asymmetric unit; the virtually identical molecules (Ia) and (Ib) each lie about a centre of symmetry ( Fig. 1). At the core of each molecule there is a planar rectangular Cu 2 S 2 ring, in which the Cu atoms have distorted tetrahedral geometry and the S atoms show a trigonal pyramidal arrangement. The largest difference in bond lengths between the two molecules is 0.08 Å between the bonds C332-H332 in (Ia) and C632-H632 in (Ib), and the largest difference in bond angles is 5 between the angles C23-N22-H22 in (Ia) and C53-N52-H52 in (IIb).
Each Cu atom in (I) is in a distorted tetrahedral geometry, the major deviations from the ideal being the S-Cu-S 0 /S-Cu-P angles of 89.36 (2)/121.94 (2) and 88.40 (2)/120.99 (2) in (Ia) and (Ib), respectively (see Table 1), where 0 indicates an atom related by an inversion centre. This distortion is similar to that found in (II) and (III), with that in (IV) being slightly less extreme [99.7 (1)/118.7 (1) ]. The bridging angles about the Cu atoms in (I), together with the Cu-S-Cu 0 angles, show a slightly distorted rectangular Cu 2 S 2 plane, which is similar to the slightly distorted square plane in (III) [S-Cu-S 0 = 88.5 (1) ] but different from the parallelogram formed in (IV) [S-Cu-S 0 = 105.7 (1) ].
The C 5 N groups are essentially planar with the N atoms lying furthest from the mean planes at 0.007 (3) Å in both (Ia) and (Ib). The pyridinium H atoms in both molecules lie 0.12 (3) Å from the respective planes. The S atoms lie 0.084 (3) and 0.109 (3) Å from the planes, which are tilted with respect to the Cu 2 S 2 planes; the angles between the normals to these planes are 119.55 (5) and 123.09 (5) respectively. The CuClP planes lie at approximate right angles to the Cu 2 S 2 planes, with angles between the normals to the planes of 95.22 (2) and 94.27 (2) in the two molecules. The P atoms also have distorted tetrahedral geometries, with angles in the ranges 102.76 (8)-120.59 (6) in (Ia) and 102.59 (8)-120.54 (6) in (Ib) (see Table 1); this is similar to structures (II) and (III), where the angles lie in the ranges 99.58 (9)-119.92 (12) and 102.4 (3)-122.5 (2) respectively. Other bond dimensions within the ligands of (I) are as expected.
There is intramolecular hydrogen bonding between the pyridinium N-H H atoms and the Cl atoms at distances of 2.37 (3) and 2.30 (2) Å in (Ia) and (Ib), respectively. This is also evident in (II) and (III), with intermolecular hydrogen bonding present in (IV) between both pyridinium H atoms of the terminal S{C 5 H 5 N} ligands and two chloride ions (see Table 2).
In the crystal packing of (I), the (PPh 3 ) phenyl groups lie in layers parallel to the crystallographic ab plane with normal van der Waals contacts between groups in neighbouring layers, the closest being C21Á Á ÁC25 iii = 3.298 (3) Å and C51Á Á ÁC55 iv = 3.303 (3) Å [symmetry codes: (iii) 2 À x, 2 À y, 1 À z; (iv) 1 À x, Ày, 2 À z); these layers alternate with the Cu 2 Cl 2 (S{C 5 H 5 N}) layers along the crystallographic c axis (Fig. 2). When viewed along the crystallographic c axis, the molecules form columns arranged with each column surrounded by six others. This arrangement is the same as that in (III) and similar to the packing of the monomer (II), where the full (PPh 3 ) ligand forms layers alternating with the Cu 2 Cl 2 (S{C 5 H 5 N}) layers. It is also similar to the packing of (IV), where two (S{C 5 H 5 N}) ligands and the (C 5 H 5 N) groups of two further (S{C 5 H 5 N}) ligands form layers alternating with layers formed by the Cu atoms, the S atoms of two (S{C 5 H 5 N}) ligands and the remaining two (S{C 5 H 5 N}) ligands.
These results, with similarities in structure, hydrogen bonding and crystal packing between the title compound (I) and the reported structures (II), (III) and (IV), show that bond dimensions and geometries in (I) are not unusual.

Figure 2
Packing diagram of (I), viewed along the crystallographic a axis. H atoms have been omitted for clarity.
We thank the Chemical Database Service, Science and Engineering Research Council, Daresbury Laboratory, England.  Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Data were corrected for Lorentz-polarization effects and decay of the intensities (CAD-4 1992), absortption (Sheldrick et al. 1977) and negative intensities (French et al. 1978) before structure solution and refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.