An electron spin resonance study of the dimeric form of some copper(II) Schiff-base complexes

Abstract

The X-band e.s.r. spectra due to the copper(II) Schiff-base complexes, namely bis(N-methylsalicylaldiminato)-copper(II), NN′-ethylenebis(salicylideneiminato)copper(II), NN′-phenylenebis(salicylideneiminato)copper(II), NN′-ethylenebis(o-aminobenzylideneiminato)copper(II), and NN′-phenylenebis(o-aminobenzylideneiminato)-copper(II) in chloroform solution at 77 K exhibit low-field lines, which are attributed to ΔM_s=±2 transitions within the triplet state due to dimeric forms of these complexes which exist in frozen solution. The salient features of the low-field lines have been satisfactorily accounted for by means of computer simulated spectra based on dipole–dipole coupled pairs of copper(II) ions in dimers with lower than axial symmetry. The results obtained for the internuclear separations of the copper(II) ions are compared with those obtained from crystallographic data.