Thermal and spectral properties of Cu(II)-5-halogenosalicylates with or without nicotinamide

Abstract

This paper deals with the preparation and investigation of thermal and spectral properties of the complexes Cu(5-ClSal)2·2H2O (I), Cu(5-BrSal)2·2H2O (II), Cu(5-ClSal)2(nia)(H2O) (III), Cu(5-BrSal)2(nia)(H2O) (IV), and Cu(5-ISal)2(nia)(H2O) (V) (where Sal=salicylate, and nia=nicotinamide). TG, DTG, DTA, EPR, IR and electronic spectra have been used to study thermal and spectral properties of the complexes. The chemical composition of the complexes, the solid intermediates and the resultant products of thermolysis have been identified by means of elemental analysis and complexometric titration. Schemes of the decomposition of the complexes are suggested. Heating of the compounds first resulted in the release of water molecules. The thermal stability of these complexes can be ordered in the sequence: I <II <IV=V< III. The final product of the thermal decomposition was CuO in all cases. IR data suggested a bidentate coordination of carboxylates to Cu(II) in complexes I-II and bridging ones for complexes III-V.