Effect of axial ligands upon the electronic absorption spectrum of phthalocyanineiron(II)

Abstract

The electronic absorption spectra of a series of compounds having the general formula phthalo-cyanineiron(II)(L)₂ have been measured in the range 12–35 kK. L represents a ligand at one of the axial positions. In general, the spectra consist of four major bands and several minor ones. The energies of the two bands of highest energy appear to be linearly related both to one another and to the σ-donor strength of the axial ligand L as measured by the affinity of L for the Zn²⁺ ion in water. The band that occurs at about 30 kK in phthalocyanine spectra does not appear to be the analogue of the Soret band occurring at about 25 kK in porphyrin spectra. These results are in general agreement with recent theoretical treatments of this type of molecule.