Influence of the electronic configuration of the central metal ions on catalytic activity of metal phthalocyanines to Li/SOCl₂ battery

The relative energy of Li/SOCl₂ battery whose electrolyte contains the transition metal phthalocyanines is used to evaluate the catalytic activity of the compounds. The energy of Li/SOCl₂ battery whose electrolyte contains transition metal phthalocyanines-tetracarboxylic acid (MPcTc) and metal phthalocyanines-tetrasulfonic acid (MPcTs) (M = Mn²⁺, Ni²⁺) increases by approximately 62-106%, the energy of Li/SOCl₂ battery whose electrolyte contains MPcTc and MPcTs (M = Fe²⁺, Co²⁺) increases by approximately 32-52%, and the energy of Li/SOCl₂ battery whose electrolyte contains CuPcTc and CuPcTs is similar to that of the cell in the absence of these complexes. It shows that the electronic configuration of the central metal ion strongly influences the catalytic activity of metal phthalocyanine to Li/SOCl₂ battery. To the same ligand, the compound whose central metal ion with electronic configuration d⁹ is inactive; the compound whose central metal ion with electronic configuration d⁴ or d⁸ exhibits relatively high catalytic activity; and the compound whose central metal ion with electronic configuration d⁵ or d⁷ exhibits relatively low catalytic activity. Three possible routes of catalytic reduction of SOCl₂ by transition metal phthalocyanine compound are proposed to interpret the results.