An electron spin resonance study of the metal ion separations in dimeric copper(II) and vanadyl chelates of 4,4′,4″,4‴-tetrasulphophthalocyanine

Abstract

Electron spin resonance measurements involving water–dimethylformamide solutions of the copper(II) and vanadayl chelates of 4,4′4″,4‴-tetrasulphophthalocyanine carried out at room temperature and 77 K provide good evidence for the formation of dimers. The spectra obtained at 77 K, attributable to dimeric forms of the chelates, arise from triplet state formation. Use of an appropriate spin Hamiltonian enables the simulation of the dimer e.s.r. lineshape. The resulting calculations provide values of the magnetic parameters for the triplet state and allow a determination of the metal-ion separations, which give a measure of the interplanar distance in the dimeric chelates, by use of the magnetic dipole–dipole interaction model. Spectra obtained by use of varying solvent mixtures provide information on the distribution of the chelate species in terms of monomeric, dimeric, and polymeric forms.