Investigations on the Thermal Reactivity of ZnII and CdII Selenocyanato Coordination Compounds

Abstract

AbstractReaction of zinc(II) and cadmium(II) selenocyanate with pyridine leads to the formation of new zinc(II) and cadmium(II) selenocyanato coordination compounds. The crystal structures of bis(selenocyanato‐N)‐tetrakis(pyridine‐N) zinc(II) (1) and bis(selenocyanato‐N)‐tetrakis(pyridine‐N) cadmium(II) (2) consist of discrete complexes in which the metal cations are octahedrally coordinated by two terminal N‐bonded selenocyanato anions and four pyridine molecules. Investigations on the thermal degradation behavior of 1 and 2 using simultaneous differential thermoanalysis and thermogravimetry as well as X‐ray powder diffraction, IR‐ and Raman spectroscopy, prove that on heating the pyridine‐rich compounds 1 and 2, a stepwise decomposition is observed, which leads to the formation of the pyridine‐deficient compounds bis(selenocyanato‐N)‐bis(pyridine‐N) zinc(II) (3) and catena‐[bis(μ‐1,3‐selenocyanato‐N,S)‐bis(pyridine‐N) cadmium(II)] (4) as intermediates. Whereas the octahedral coordination of the CdII cations are unchanged in its pyridine‐deficient intermediate 4, that is build up of polymeric chains, the crystal structure of compound 3 consists of tetrahedrally coordinated ZnII atoms, which are surrounded by two N‐bonded selenocyanato anions and two pyridine ligands forming discrete complexes. The structures and the thermal reactivity are discussed and compared with that of related transition metal isothiocyanates and selenocyanates with pyridine.