Thermal decomposition kinetics of mixed ligand complexes of cobaloxime with 1-benzyl-2-phenylbenzimidazole

Abstract

Cobaloxime complexes of the type [Co(DH) 2(BPBI)X], where BPBI is 1-benzyl-2-phenyl-benzimidazole and X = Cl, Br, I or SCN, were subjected to a systematic thermogravimetric, differential thermogravimetry and differential thermal analysis. All the complexes decompose just after melting, and the decomposition process consists essentially of three stages. The final residue in all cases was found to be CoO. The mass loss data indicate the formation of intermediate complexes with an approximate composition of [Co(DH)2(BPBI)] at the end of the first stage of decomposition. The kinetic parameters were calculated using the Coats-Redfern equation. The E a values for the first stage of the decomposition are seen to decrease in the following order: thiocyanato complex > chloro complex > bromo complex > iodo complex. The E a and Δ S values for the second and third stages of decomposition indicate catalytic activity of the intermediate complexes formed during these stages.