FACILE PLANAR-NONPLANAR N-AMIDO INTERCONVERSION AT A COIII CENTRE

Abstract The reaction of Co(OAC) 2 with excess H 2 bpb [H 2 bpb = 1,2-bis(2-pyridinecarboxamido)benzene] led to the isolation of Co(bpb) (OH 2 ) and a Co III nonplanar tetradentate amino complex Co(bpb)( n 2 -Hbpb) ( 1 ), which has been characterized by X-ray crystallography. The geometry of 1 is octahedral with the Hbpb ligand coordinated in a cis fashion via a pyridyl and an amino oxygen, leaving the bpb in a nonplanar bonding mode. Other chelating bidentate ligands were also found to promote the nonplanar tetradentate binding mode of bpb, for example in [Co( n 4 -bpb)( n 2 -S 2 CNEt 2 ] which was prepared by reaction of Co(bpb)·(OH 2 ) with Na(S 2 CNEt 2 ) in air.