Thermal properties of cyanatocopper(II) complexes with pyridine, bipyridine and phenanthroline

Abstract

The thermal properties of cyanatocopper complexes with pyridine, bipyridine and phenanthroline are described in this paper. It was found that the thermal stabilities of the complexes were found to increase in the order py<<bipy<phen ligands. The significantly higher thermal stability of the complexes with bipyridine and phenanthroline is caused by the presence of dimeric structural units in the crystal structure and intermolecular interactions of the cyanate and heterocyclic ligands.In our preceding papers we have described the thermal decompositions of thiocyanatoeopper complexes CuL2(NCS)2 (L=pyridine and its methyl derivates) which are composed of the liberation of ligands L and redox reactions of thiocyanate ligands with the central Cu(ll) atom [1, 2]. The decomposition temperature of thiocyanate ligands depends on the properties of the ligands L present in the coordination sphere. An analogous course of thermal decomposition was also observed for [Cu(bipy)2(NCX)](NCX) (X=S or Se) [3]. For the phenanthroline complexes [Cu(phen)2(NCX)2] (X=S or Se) the thermal stability was found to increase significantly (by about 140~ and the decomposition stoichiometry was also changed [31.The present paper contains the results of thermoanalytical studies on bipyridine and phenanthroline cyanatocopper complexes, and a comparison of the thermal properties of pyridine cyanato and isothioeyanatocopper complexes.(phen=phenanthroline) were prepared as described earlier [4, 5].The intermediates of thermal decomposition were obtained by thermal degradation of the initial compounds until the specific mass determined from the thermoanalytical curves was attained. In the starting complexes and intermedi- 0368.-.4466