New group 6 metal carbonyl complexes with 4,5-dimethyl-N,N-bis(pyridine-2-yl-methylene)benzene-1,2-diimine Schiff base: Synthesis, spectral, cyclic voltammetry and biological activity studies

Thermal reaction of M(CO)(6) (M = Cr, Mo or W) with a Schiff base (DMPA) derived from the condensation of 4,5-dimethyl-1,2-phenylenediamine and pyridine-2-carboxaldehyde in THF in absence and presence of a secondary ligand; 2-aminobenzimidazole (Abz), thiourea (Tu) or 2-(2'-pyridyl)benzimidazole (pybz) were studied. The reaction of Cr(CO)(6) gave the four complexes Cr-2(CO)(2)(DMPA)(2); 1, Cr(DMPA)(2)(Abz)(2); 2, Cr-2(CO)(4)(DMPA)(2)(Tu)(2); 3 and Cr(DMPA)(2)(Pybz); 4, while the thermal reaction of Mo(CO)(6) resulted in the formation of the two complexes Mo-2(O)(6)(DMPA)(2); 5, and Mo-2(O)(2)(CO)(2)(DMPA)(2)(Tu)(2); 6. Thermal reaction of W(CO)(6) and the Schiff base DMPA gave the complex W(O)(2)(DMPA)(2); 7. The ligand DMPA and its metal complexes have been reported and characterized based on elemental analyses, IR, H-1 NMR, magnetic measurements, and thermal analysis. Cyclic voltammetry and biological activity were also investigated. (C) 2015 Elsevier B.V. All rights reserved.