E.s.r. and optical spectral properties of copper(II) complexes with Schiff-base ligands derived from o-aminobenzaldehyde

Abstract

Optical and e.s.r. spectra have been measured for a number of copper(II) complexes with Schiff-base ligands derived from o-aminobenzaldehyde. Absorption bands at ca. 39 500 and 24 000 cm^–1 are proposed as π→π* transitions, the latter being split into two components in complexes with quadridentate ligands. Bands at ca. 19 000 and 14 000 cm^–1 are attributed to transitions within the copper 3d shell. An absorption near 22 000cm^–1 is assigned to a π→d_xy transition. The optical and e.s.r. parameters of the complexes are consistent with planar co-ordination of the copper ion except for NN′-1,3-propylenebis(o-aminobenzylideneiminato)copper(II), in which a small tetrahedral distortion of the co-ordination sphere is indicated. The strong ligand field exerted by the o-aminobenzylideneimine ligands precludes additional axial co-ordination of solvent molecules.