Syntheses, structures and characterization of cobalt(II) and cobalt(III) complexes with N-benzylated polyamines and a terminal azido ligand

Mononuclear cobalt(II) and cobalt(III) complexes, [Co(trenb)(N(3))]Cl (1) and [Co(dienb)(N(3))(2)(OAc)] (2) (trenb =tris[2-(benzylamino)ethyl]amine, dienb=1,9-diphenyl-2,5,8-triazanonane) were synthesized and characterized by elemental analyses, IR and electronic spectra. Their crystal structures were also determined by X-ray diffraction analyses. In Complex 1, cobalt(II) is five-coordinate trigonal bipyramidal with one azido nitrogen atom and four nitrogen donors of the tripodal ligand; the chloride interacts weakly with one of the secondary amino groups of trenb via a hydrogen bond. In Complex 2, cobalt(III) is in a distorted octahedral coordination environment, consisting of three nitrogen atoms of the amine ligand, two azide nitrogen atoms and an oxygen atom of the acetate ion; a six-membered ring involving the hydrogen bond may stabilize the complex, which maintains its solid geometry in DMF as indicated by the electronic spectrum.