Unusual catalytic effect of halide anions in the protolytic dissociation of indium(III) octaphenyltetraazaporphyrins

Chloro(octaphenyltetraazaporphyrinato)indium(III) [(Cl)InOPTAP] dissociates easily in slightly acidified dichloromethane solutions (0.001–0.01 M CF₃COOH) after addition of tetraethylammonium chloride; the observed catalytic effect of chloride anions is due to their additional cis-coordination to the In atom with formation of the dianionic complex [(Cl)₃InOPTAP]^2–.