Syntheses and crystal structures of bis(4-methylpyridine-κN)bis(selenocyanato-κN)zinc(II) and catena-poly[[bis(4-methylpyridine-κN)cadmium(II)]-di-μ-selenocyanato-κ2N:Se;κ2Se:N]

The reactions of Zn(NO3) 2.6H(2)O and Cd(NO3) 2.4H(2)O with KSeCN and 4-methylpyridine (C6H7N; 4-picoline) lead to the formation of crystals of bis(4-methylpyridine-kappa N)bis(selenocyanato- kappa N)zinc(II), [Cd(NCSe)(2)(C6H7N)(2)] (1), and catena-poly[[ bis(4-methylpyridine-kappa N)cadmium(II)]-di-mu-selenocyanato-kappa N-2:Se;kappa Se-2:N], [Cd(NCSe)(2)(C6H7N)(2)] n (2), suitable for single-crystal X-ray diffraction. The asymmetric unit of compound 1 consists of one Zn cation that is located on a twofold rotation axis as well as one selenocyanate anion and one 4-methylpyridine ligand in general positions. The Zn cations are tetrahedrally coordinated by two terminal N-bonding thiocyanate anions and two 4-methylpyridine ligands, forming discrete complexes. The asymmetric unit of compound 2 consists of two crystallographically independent Cd cations, of which one is located on a twofold rotation axis and the second on a center of inversion, as well as two crystallographically independent selenocyanate anions and two crystallographically independent 4-methylpyridine ligands in general positions. The Cd cations are octahedrally coordinated by two N- and two Sbonding selenocyanate anions and two 4-methylpyridine ligands and are linked into chains by pairs of selenocyanate anions. Within the chains, the Cd cations show an alternating cis-cis-trans and all-trans coordination and therefore, the chains are corrugated. PXRD investigations prove that the Zn compound was obtained as a pure phase and that the Cd compound contains a very small amount of an additional and unknown phase. In the IR spectrum of 1, the CN stretching vibration of the selenocyanate anion is observed at 2072 cm(-1), whereas in the 2 it is shifted to 2094 cm(-1), in agreement with the crystal structures.