Synthesis, crystal structure and thermal properties of tetrakis(3-methylpyridine-κN)bis(thiocyanato-κN)nickel(II)

Abstract

Reaction of Ni(NCS)2 with 3-methylpyridine in water leads to the formation of crystals of the title compound, [Ni(NCS)2(C6H7N)4]. All of them are of poor quality and non-merohedrally twinned but a refinement using data in HKLF-5 format leads to a reasonable structure model and reliability factors. The crystal structure of the title compound consists of discrete complexes, in which the nickel cations are sixfold coordinated by two terminal N-bonded thiocyanate anions and four 3-methylpyridine ligands within slightly distorted octahedra. One of the 3-methylpyridine ligands is disordered and was refined using a split model. The discrete complexes are arranged into layers. X-ray powder diffraction proves that pure samples have been obtained, and in the IR spectrum, the CN stretching vibration is observed at 2072 cm−1, in agreement with the presence of only terminally coordinated thiocyanate anions. Comparing the calculated powder pattern with those of the residues obtained by solvent removal from several solvates already reported in the literature proves that, in each case, this crystalline phase is formed. Assessing the crystal structures of the solvates in comparison with that of the ansolvate reveals some similarities.