Salts with titanyl and vanadyl phthalocyanine radical anions. Molecular design and effect of cations on the structure and magnetic and optical properties

Abstract

Radical anion salts of metal phthalocyanines have been providing a new family of compounds which can potentially possess promising optical, magnetic and conducting properties. Essential progress in this field has been reached only recently when series of salts of phthalocyanines with different metals and axial substituents were obtained. In this work we summarize our recent results about the radical anion salts of titanyl (Ti^IVOPc) and vanadyl (V^IVOPc) phthalocyanines and nine new salts of these phthalocyanines are discussed. Different synthetic approaches for the preparation of these salts are presented, and the effect of the size and shape of counter cations on the crystal structures of the salts and consequently their magnetic and optical properties are considered. The {Ti^IVO(Pc˙³⁻)}˙⁻ radical anions have an S = 1/2 spin on the Pc˙³⁻ macrocycle, whereas the {V^IVO(Pc˙³⁻)}˙⁻ radical anions have two S = 1/2 spins on both the Pc˙³⁻ macrocycle and the central V^IV atom. Therefore, it is possible to compare the magnetic properties of isostructural compounds with different magnetic states of metal phthalocyanines. We also discuss the effect of reduction on the molecular structure and the optical and magnetic properties of negatively charged titanyl and vanadyl phthalocyanines.