Studies on the salts of planar metal dithiolate anions with the redox active 3,7-bis(dimethylamino)phenothiazin-5-ium cation (methylene blue)

Abstract

The preparation of two series of 3,7-bis(dimethylamino)phenothiazin-5-ium (methylene blue, mb) salts with [M{S₂C₂(CN)₂}₂]^2– and [M{S₂C₂(CN)₂}₂]^–(M = Ni, Pd, Pt, or Cu) is described. Compressed pellets of all these compounds exhibit conductivities of less than 10^–5Ω^–1 cm^–1 at room temperature. Single crystals of [mb][Pt{S₂C₂(CN)₂}₂] behave as semiconductors with an activation energy of 238 meV and a room-temperature conductivity of 10^–5Ω^–1 cm^–1.