Thermo-decomposition kinetics and representative structure of homologous dinuclear complexes

The title complex with formally heptadentate dinucleating ligands L, [Ni2L2](py)2(H2O)2 (L=C31H28N2O7 dianion), was synthesized, characterized by elemental analyses and IR spectroscopy, and structurally determined by X-ray diffraction technique. In the center-symmetric unit [Ni2L2], two phenolates and two Schiff-base imino groups of each L, as a practical tetradentate ligand, bond two Ni atoms to form square-distortionally tetrahedral coordination geometries, D2d symmetry. This nickel(II) complex and its homologue [Cu2L2](py)2(H2O)2 were both studied by TG–DTG technique under non-isothermal conditions. The relationship between weight loss and coordinations of L in each complex was inferred in the thermal decomposition processes. The most probable kinetic mechanism, Zhuralev–Lesokin–Tempelman equition, was determined by using the combined differential and integral methods, and the related values of activation energy E and pre-exponential factor A were calculated, respectively, for each complex.