Dichlorido(di-2-pyridyl sulfide-κ2 N,N′)zinc(II)

The crystal structure of the title compound, [ZnCl2(C10H8N2S)], consists of a six-membered chelate ring in which the Zn atom is approximately tetrahedrally coordinated by two chloride ions and by the two pyridyl N atoms of a single di-2-pyridyl sulfide ligand. As usual for this type of complex, the sulfide group does not participate in zinc coordination. The dihedral angle between the two pyridine rings is 50.4 (1)°.

The crystal structure of the title compound, [ZnCl 2 (C 10 H 8 N 2 S)], consists of a six-membered chelate ring in which the Zn atom is approximately tetrahedrally coordinated by two chloride ions and by the two pyridyl N atoms of a single di-2-pyridyl sulfide ligand. As usual for this type of complex, the sulfide group does not participate in zinc coordination. The dihedral angle between the two pyridine rings is 50.4 (1) .

Experimental
Crystal data [ZnCl 2 (C 10  Recently, we are interested in the synthesis, structures and thermal properties of coordination polymers based on zinc (II) halides and N-donor ligands (Bhosekar et al., 2007). We have found for example that most of the ligand rich compounds can be transformed into ligand deficient compounds on heating. Starting from these findings we have initiated systematic investigations on this topic. In these investigations we have reacted zinc(II) chloride with 2,2'-bipyridyldisulfide. In this reaction, simultaneously a cleavage of the S-S bond takes place leading to the formation of di-2-pyridyl sulfide (dps). In further reaction with zinc(II) chloride the title compound (I) is formed. To identify this product in further reaction by X-ray powder diffraction, a structure determination was performed.
In general dps is a versatile ambidentate ligand that, due to its conformational flexibility, can act in N,N'-bidentate (Tresoldi et al., 1992;Kondo et al., 1995 andNicolò et al., 1996) or bridging (Tresoldi et al., 1991 andTeles et al., 1999) coordination modes toward many metals, resulting in complexes with different stereochemistry. When dps is bonded to the metal as a chelate ligand, a six-membered ring in boat conformation is formed, differently from its rigid analogues 2,2'bipyridine that generates a pentacyclic chelate in a planar arragement. In addition, in some cases dps can act as tridentate ligand in a N,N,S-coordination mode involving metal-sulfur interactions (Anderson & Steel, 1998).
In the crystal structure the coordination geometry about the Zn(II) ion is approximately tetrahedral with bonds being formed to two chloride ions and the two pyridyl nitrogen atoms of a single dps ligand (Fig. 1). These latter interactions result in the formation of a six-membered chelate ring, which is in a boat conformation. The angles at Zn(II) range from 93.85 to 115.66°, the largest being N-Zn-Cl. The Zn-Cl and Zn-N distances are in the range of 2.057 (2)-2.061 (2) and 2.2192 (8)-2.2261 (8) Å. The structural parameters in the dps molecule are quite regular. In particular the C-S bonds, 1.782 (3) and 1.780 (3) Å, are in good agreement with those expected for C(sp 2 )-S bonds (1.77 Å).

Experimental
ZnCl 2 and 2,2'-bipyridyldisulfide was obtained from Alfa Aesar and methanol was obtained from Fluka. 0.0313 mmol (4.3 mg) zinc(II) chloride, 0.125 mmol (27.5 mg) 2,2'-bipyridyldisulfide and 3 ml of methanol were transfered in test-tube, which were closed and heated to 110 °C for three days. On cooling colourless block-shaped single crystals of (I) are obtained.

Refinement
All H atoms were located in difference map but were positioned with idealized geometry and were refined isotropic with U eq (H) = 1.2U eq (C) of the parent atom using a riding model with C-H = 0.97 Å.
supplementary materials sup-2 Figures   Fig. 1. : Crystal structure of compound I with labelling and displacement ellipsoids drawn at the 50% probability level.
Dichlorido(di-2-pyridyl sulfide-κ 2 N,N')zinc (II) Crystal data [ZnCl 2 (C 10  Refinement. 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 Rfactors(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Geometric parameters (Å, °)