synthesis, characterization and x-ray crystal structure of a cobalt(iii) complex with 2-bis(pyridine-2-carboxamido)-4,5-dimethylbenzene ligand

an octahedral cobalt(iii) complex, trans-[(me2bpb)co(bzlan)2]clo4 (1), with h2me2bpb = n,n’-(4,5-dimethyl-1,2-phenylene)dipicolinamide and bzlan = benzylamine, has been synthesized and characterized by elemental analyses, ir, uv-vis, and 1h nmr spectroscopy. the structure of this complex has been determined by x-ray crystallography. the me2bpb2– is a di-anionic tetradentate ligand furnishing a n4 set, such that two n atoms of the two pyridine rings and two amido n atoms occupy four equatorial positions. the two benzylamine ligands occupy the two axial positions leading to a distorted octahedral geometry around the central cobalt ion. the electrochemical behavior of this complex in acetonitrile solution indicates that the irreversible oxidation of 4,5-dimethylorthophenylene moiety and reduction of pyridine rings of the free ligand appear as reversible waves in the cyclic voltammogram of its cobalt(iii) complex. concomitant coiii/coii redox process and solvolysis in acetonitrile solution is observed. this irreversible redox process becomes reversible in the presence of excess benzylamine.