Effects of macrocyclic ligand structure and axial ligation on the ligand-field spectra of tetra-azamacrocyclic copper(II) complexes in co-ordinating solventst

Abstract

Four closely related 14-membered tetra-azamacrocyclic copper(II) complexes have been synthesized, and their ligand-field spectra in water, methanol, dimethylformamide, and dimethyl sulphoxide have been studied. In these solutions all the complexes contain tetragonal copper(II), and are of the general formula [CuL(solv)₂]²⁺(L = macrocyclic ligand, solv = solvent). The equatorial ligand-field strength is affected by the macrocyclic ligand structure; on the other hand, the axial ligand-field strength is affected by the donor ability of the co-ordinating solvent. Linear relationships between the d–d transition energies for the complexes and the donor numbers of the solvents were obtained.