Jahn–Teller Distortions of Metal Phthalocyanine Anions [MIVOPc]n– (M = Ti, V)

Abstract

Based on X-ray diffraction data, a comparative analysis of the molecular geometry of eight phthalocyanine anions [TiIVOPc]n–, [VIVOPc]n– (n = 1, 2) and neutral phthalocyanines [TiIVOPc] and [VIVOPc] is carried out to study Jahn–Teller distortions of their molecular structure. It is experimentally shown that the occupation of a doubly degenerate lowest unoccupied molecular orbital of the [MIVOPc] molecule level by additional electrons leads to core tetragonal symmetry lowering from $${{C}_{{4{v}}}}$$ to $${{C}_{{2{v}}}}$$ with a significant change in the bond lengths distribution in the molecule. The effect manifests itself to a greater extent in imine bonds of the C–Nim–C fragment, in which a systemic alternation of bonds into short and long is observed. The degree of distortion is proportional to the charge of the metal phthalocyanine macrocycle of the organic part of the molecule, C32H16N8. The Jahn–Teller distortions of the macrocycle noticeably affect the position of frequencies characteristic of [MIVOPc] in the Raman spectra of single crystals of anionic phthalocyanine complexes in the range 1100–1700 cm–1. The experimental patterns agree fairly well with the results of DFT calculations.