The thermal decomposition of Mg(II) complexes with SCN, pyridine, nicotinamide and N, N-diethylnicotinamide

Abstract

The thermal decomposition of the complexes Mg(SCN) 2·5H 2O ( I), Mg(SCN) 2Py·H 2O ( II), Mg(SCN) 2(NIA) 4·3H 2O ( III) and Mg(SCN) 2(DENIA) 2·H 2O ( IV), where Py, pyridine; NIA, nicotinamide and DENIA, N, N-diethylnicotinamide had been investigated in static air in temperature range 20–1000°C by means of thermogravimetry (TG), differential thermogravimetry (DTG) and differential thermal analysis (DTA). The composition of the complexes and the solid state intermediate and resultant products of thermolysis had been identified by means of elemental analysis and compleximetric titration. The possible scheme of destruction of the complexes is suggested. The final product of the thermal decomposition was MgS for the complexes I– IV. According to the decomposition temperatures, the thermal stability of the complexes can be ordered in the sequence: II< III< IV< I. By means of IR spectral analysis the stereochemistry around Mg(II) atom in the compounds had been studied. Py, NIA and DENIA were coordinated to Mg(II) through the nitrogen atom of their heterocyclic ring. IR data suggest that the SCN group is coordinated to Mg(II) through sulphur in complexes I and II and through nitrogen and sulphur in complexes III and IV.