Cobalt(III) alkyl complexes of 1,2-bis(2-pyridinecarboxamido)benzene (H2bpb) and 4,5-dichloro-1,2-bis(2-pyridinecarboxamido)benzene (H2bpc) and X-ray crystal structures of [Co(bpc)(CH2CH2CMeCH2)(H2O)] and [Co(bpb)Et(H2O)]

Abstract

A series of organo and non-organo cobalt complexes of bpb and bpc ligands [H₂bpb = 1,2-bis(2-pyridinecarboxamido)benzene, H₂bpc = 4,5-dichloro-1,2-bis(2-pyridinecarboxamido)benzene] have been synthesised. Complexes prepared include Na[CoL(CN)₂], Na[CoL(N₃)₂], [CoL(py)₂]ClO₄ and [CoL(R)(H₂O)](L = bpb or bpc; py = pyridine; R = Me, Et, Prⁱ or CH₂CH₂CMeCH₂). The complex [CoL(CH₂CH₂CMeCH₂)(H₂O)] was formed as a rearrangement product from the reaction of 3,3-dimethylallyl bromide and [CoL]·H₂O in the presence of NaBH₄ and NaOH in methanol. The complexes [Co(bpc)(CH₂CH₂CMeCH₂)(H₂O)]1 and [Co(bpb)Et(H₂O)]2 have been characterized by X-ray crystallography: 1, space group Pnma, a= 13.934(2), b= 12.204(2), c= 13.173(2)Å, Z= 4, and R= 0.046 for 1129 observed reflections; 2, space group Pnma, a= 15.072(1), b= 12.119(2), c= 9.884(3)Å, Z= 4, and R= 0.034 for 1387 observed reflections. Electrochemical studies on the one-electron oxidation of these complexes suggest the involvement of the equatorial ligand in these processes.