Synthesis, Structures, and Properties of Crystalline Salts with Radical Anions of Metal-Containing and Metal-Free Phthalocyanines

Radical anion salts of metal‐containing and metal‐free phthalocyanines [MPc(3−)].−, where M=CuII, NiII, H2, SnII, PbII, TiIVO, and VIVO (1–10) with tetraalkylammonium cations have been obtained as single crystals by phthalocyanine reduction with sodium fluorenone ketyl. Their formation is accompanied by the Pc ligand reduction and affects the molecular structure of metal phthalocyanine radical anions as well as their optical and magnetic properties. Radical anions are characterized by the alternation of short and long CNimine bonds in the Pc ligand owing to the disruption of its aromaticity. Salts 1–10 show new bands at 833–1041 nm in the NIR range, whereas the Q‐ and Soret bands are blue‐shifted by 0.13–0.25 eV (38‐92 nm) and 0.04–0.07 eV (4–13 nm), respectively. Radical anions with NiII, SnII, PbII, and TiIVO have S=1/2 spin state, whereas [CuIIPc(3−)].− and [VIVOPc(3−)].− containing paramagnetic CuII and VIVO have two S=1/2 spins per radical anion. Central metal atoms strongly affect EPR spectra of phthalocyanine radical anions. Instead of narrow EPR signals characteristic of metal‐free phthalocyanine radical anions [H2Pc(3−)].− (linewidth of 0.08–0.24 mT), broad EPR signals are manifested (linewidth of 2–70 mT) with g‐factors and linewidths that are strongly temperature‐dependent. Salt 11 containing the [NaIPc(2−)]− anions as well as previously studied [FeIPc(2−)]− and [CoIPc(2−)]− anions that are formed without reduction of the Pc ligand do not show changes in molecular structure or optical and magnetic properties characteristic of [MPc(3−)].− in 1–10. Metal phthalocyanine radical anion salts containing [MPc(3−)].− (M=CuII, NiII, H2, SnII, PbII, TiIVO, VIVO) have been obtained as single crystals. Optical and magnetic data support localization of negative charge of the radical anions on the Pc ligands, providing new bands in the NIR range at 833–1041 nm and a blue‐shift of Q‐bands. Pc ligands show disruption of aromaticity upon the reduction. Central metal atoms strongly affect the EPR spectra of [MPc(3−)].−.