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 b y elemental analyses and IR spectroscopy, and structurally determined by X- ray diffraction technique. In the center-symmetric unit [Ni2L2], two phenol ates and two Schiff-base imino groups of each L, as a practical tetradentat e ligand, bond two Ni atoms to form square-distortionally tetrahedral coord ination geometries, D-2d symmetry. This nickel(II) complex and its homologu e [Cu2L2](py)(2)(H2O)(2) were both studied by TG-DTG technique under non-is othermal 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, w as 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. (C) 2001 Elsevier Science B.V. All rights reserved.