Magnetic and Optical Properties of Layered (Me₄P⁺)[M^IVO(Pc^•3–)]^•–(TPC)_0.5·C₆H₄Cl₂ Salts (M = Ti and V) Composed of π-Stacking Dimers of Titanyl and Vanadyl Phthalocyanine Radical Anions

Two isostructural salts with radical anions of titanyl and vanadyl phthalocyanines (Me4P+)[MIVO(Pc•3–)]•–(TPC)0.5·C6H4Cl2 (M = Ti (1), V (2)), where TPC is triptycene, were obtained. These salts contain phthalocyanine layers composed of the {[MIVO(Pc•3–)]•–}2 dimers with strong π–π intradimer interaction. The reduction of metal phthalocyanines was centered on the Pc macrocycles providing the appearance of new bands in the near infrared range and a blue shift of Q- and Soret bands. That results in the alternation of shorter and longer C–Nimine bonds in Pc•3–. Only one S = 1/2 spin is delocalized over Pc•3– in 1 providing a χMT value of 0.364 emu K mol–1 at 300 K. Salt 1 showed antiferromagnetic behavior approximated by the Heisenberg model for isolated pairs of antiferromagnetically interacting spins with exchange interaction of J/kB = −123.0 K. The χMT value for 2 is equal to 0.617 emu K mol–1 at 300 K to show the contribution of two S = 1/2 spins localized on VIV and delocalized over Pc•3–. Magnetic beha...