The thermal decomposition reactions of bis(pyridine-2-aldoxime)-copper(II) complexes

The thermal properties of [Cu(HL)L]Cl (HL = pyridine-2-aldoxime), [Cu(HL)2]Cl2, and CuL2 were studied in vacuo and in dynamic N2 and O2 gas atm. by thermogravimetry (TG), differential TG, DTA, UV-visible, IR, diffuse reflectance, and mass spectra. The initial decompn. temp. is affected by the no. of acid hydrogens in the complex; the thermal stability sequence in vacuo is: [Cu(HL)LCl > [Cu(HL)2]Cl2 > CuL2. The thermal decompn. reactions occur in several sep. steps, the 1st of which gives rise to partial ligand decompn., the redn. of Cu(II) to Cu(I), and the conversion of the residual HL into acid amide.