Syntheses, Structures, and Thermal Reactivity of New ZnII and CdII Thio‐ and Selenocyanato Coordination Compounds

Abstract

AbstractReaction of ZnII and CdII thiocyanate or selenocyanate with pyrazine leads to the formation of new ZnII and CdII coordination compounds. The structures of [Zn(NCSe)2(pyrazine)2]n (1A), [Cd(NCS)2(pyrazine)2]n (2A) and [Cd(NCSe)2(pyrazine)2]n (3A) consist of octahedrally coordinated metal cations which are surrounded by two terminal N‐bonded anions and two μ2‐bridging pyrazine molecules. The metal cations are connected via the pyrazine ligands into layers, which are further linked by weak intermolecular S···S respectively Se···Se interactions. Investigations on the thermal degradation behavior of 1A, 2A, and 3A using simultaneous differential thermoanalysis and thermogravimetry as well as X‐ray powder diffraction, IR‐ and Raman spectroscopy prove that on heating, the pyrazine‐rich compound 1A decomposes in one step into zinc selenocyanate without the formation of a pyrazine‐deficient intermediate. In contrast, for compounds 2A and 3A a stepwise decomposition is observed, leading to the formation of the pyrazine‐deficient compounds [Cd(NCS)2(pyrazine)]n (2B‐I and 2B‐II) and [Cd(NCSe)2(pyrazine)]n (3B) as intermediates. The structures and the thermal reactivity are discussed and compared with that of related transition metal thiocyanates and selenocyanates with pyridine as N‐donor ligand.