Electronic structures of square planar cobalt(II), nickel(II) and copper(II) complexes with some N4-macrocyclic ligands [1

Abstract

Abstract ESR and absorption spectra were measured for the square planar cobalt(II), nickel(II) and copper(II) complexes with some 14, 15 and 16-membmered N4macrocyclic ligands, such at (14-a), H(14-b), H2(14-c), H2(15-c) and H2(16-c) (for the abbreviations, see Fig. 2 in the text). On the basis of the ESR spectra of the cobalt(II) complexes, the splitting schemes for the cobalt d-orbitals were grouped into two types, (1) [Co(14-a)]2+ and [Co(14-b)]+ where no or little π-antibonding interaction is present and (2) [Co(14-c)], [Co(15-c)] and [Co(16-c )] where a considerable π-antibonding interaction is present. The electronic spectra of the cobalt(II), nickel(II) and copper(II) complexes were reasonably interpreted in terms of the model proposed.