Synthesis, characterization and electrochemistry of carboxamido Co(III) complexes: The crystal structure of [CoIII(Mebpb)(N-MeIm)2]BPh4·CH3OH

Abstract

Three cobalt(III) complexes of the type trans -[Co III (Mebpb)(amine) 2 ]X {Mebpb 2− = N,N ′-bis(pyridine-2-carboxamido)-4-methylbenzene dianion, and amine = N -methylimidazole ( N -MeIm) ( 1 ), 3-methylpyridine (3-MePy) ( 2 ), 3-acetylpyridine (3-AcPy) ( 3 ), X = BPh 4 - ( 1 ), ClO 4 - ( 2, 3 )} were synthesized and characterized by elemental analyses, IR, UV–Vis, and 1 H NMR spectroscopy. The structure of 1 ·CH 3 OH was determined by X-ray crystallography and was found to have a distorted octahedral geometry around Co. The electrochemical behavior of these complexes with the goal of evaluating the effect of axial ligation on the redox properties is also reported. The reduction potential of Co(III), ranging from −0.63 V for ( 1 ) to −0.20 V for ( 3 ) shows a relatively good correlation with the σ-donor ability of the axial ligands.