Synthesis, crystal structure and properties of poly[(μ-2-methylpyridine N-oxide-κ2 O:O)bis(μ-thiocyanato-κ2 N:S)cobalt(II)]

Abstract

The title compound, [Co(NCS)2(C6H7NO)] n or Co(NCS)2(2-methylpyridine N-oxide), was prepared by the reaction of Co(NCS)2 and 2-methylpyridine N-oxide in methanol. All crystals obtained by this procedure show reticular pseudo-merohedric twinning, but after recrystallization, one crystal was found that had a minor component with only a very few overlapping reflections. The asymmetric unit consists of one CoII cation, two thiocyanate anions and one 2-methylpyridine N-oxide coligand in general positions. The CoII cations are octahedrally coordinated by two O-bonding 2-methylpyridine N-oxide ligands, as well as two S- and two N-bonding thiocyanate anions, and are connected via μ-1,3(N,S)-bridging thiocyanate anions into chains that are linked by μ-1,1(O,O) bridging coligands into layers. No pronounced directional intermolecular interactions are observed between the layers. The 2-methylpyridine coligand is disordered over two orientations and was refined using a split model with restraints. Powder X-ray diffraction (PXRD) indicates that a pure sample was obtained and IR spectroscopy confirms that bridging thiocyanate anions are present. Thermogravimetry and differential thermoanalysis (TG-DTA) shows one poorly resolved mass loss in the TG curve that is accompanied by an exothermic and an endothermic signal in the DTA curve, which indicate the decomposition of the 2-methylpyridine N-oxide coligands.