The co-ordination of salicylideneimines with transition-metal ions. Charge-transfer spectra of cobalt(II) complexes

Abstract

A charge-transfer band is found for salicylideneimine complexes of cobalt(II) in the region 25,000–27,000 cm.^–1 and can be assigned to a metal-to-ligand electron transfer. The high energy of the charge-transfer band for complexes derived from N-phenylsalicylideneimines bearing ortho-substituents on the phenyl ring is discussed in the light of steric strain. Weak bonding between the o-methoxy-groups and the metal is proposed to explain the low energy of the charge-transfer band for the chelate bis-(N-o-anisylsalicylideneiminato)cobalt(II). The analogous zinc(II) complexes do not show charge-transfer bands. The spectral characteristics of the charge-transfer bands of the cobalt(II) chelates in pyridine are also discussed.