Bis(3-methylpyridine-κN)bis(thiocyanato-κN)zinc

The asymmetric unit of the title compound, [Zn(NCS)2(C6H7N)2], consists of one Zn2+ cation and two thiocyanate anions, all situated on special positions with site symmetry .m., and one 3-methylpyridine ligand. The zinc cation is coordinated by four N atoms of two terminal N-bonded thiocyanate anions and of two symmetry-related 3-methylpyridine co-ligands, defining a slightly distorted tetrahedral coordination polyhedron.

The asymmetric unit of the title compound, [Zn(NCS) 2 -(C 6 H 7 N) 2 ], consists of one Zn 2+ cation and two thiocyanate anions, all situated on special positions with site symmetry .m., and one 3-methylpyridine ligand. The zinc cation is coordinated by four N atoms of two terminal N-bonded thiocyanate anions and of two symmetry-related 3-methylpyridine coligands, defining a slightly distorted tetrahedral coordination polyhedron.

Experimental
reactions. The compounds with Co(II) are of special interest because several of them show a slow relaxation of the magnetization which is a rare and very interesting magnetic phenomenon (Boeckmann & Näther, 2010;Boeckmann & Näther, 2011;Wöhlert et al., 2011)). Following this synthetic procedure, powders of low crystallinity are frequently obtained and therefore their structures are difficult to elucidate. Structure determinations of these compounds are of special importance because in the case of coordination polymers containing cobalt(II), both octahedral and tetrahedral coordination polyhedra can occur in these structures. In this context we found out that diamagnetic zinc and cadmium compounds can easily be crystallized in solution and are very often isotypic to their paramagnetic analogues (Bhosekar et al., 2010;Boeckmann et al., 2011a;Boeckmann et al., 2011b;Boeckmann et al., 2011c;Taniguchi et al., 1987;Wu, 2004;Zhu, 2008). The structures of the paramagnetic counterparts can then simply be refined applying the Rietveld method. This is the reason why we have determined the crystal structure of the diamagnetic title compound, [bis(thiocyanato-κN)-bis(3-methylpyridine-κN)zinc].
In the crystal structure the zinc cations (site symmetry .m.) are bonded to four nitrogen atoms of two terminal thiocyanate anions (site symmetry .m.) and to two symmetry-related terminal 3-methylpyridine co-ligands within a slightly distorted tetrahedral coordination polyhedron ( Fig. 1 and Tab.1). The discrete complexes are oppositely oriented into columns which spread along the crystallographic b axis (Fig. 2). These columns are further arranged in parallel along the crystallographic a and c axes into a three-dimensional packing.

Experimental
The title compound was prepared by the reaction of 90.0 mg Zn(NCS) 2 (0.50 mmol) and 97.3 µL 3-methylpyridine (1.00 mmol) in 1.50 ml water at RT in a closed 3 ml snap cap vial. After three days colourless block like crystals of the title compound were obtained.

Refinement
All H atoms were discernible in difference maps but were positioned with idealized geometry and were refined isotropically with U eq (H) = 1.2U eq (C) for aromatic H atoms and with U eq (H) = 1.5U eq (C) for aliphatic H atoms of the parent atom using  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 > 2sigma(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.

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