Electrochemical behavior of polymeric complexes of monosubstituted squarate ligands. Part 2. Determination of redox species of manganese(II) complexes in the donor solvents, dimethylformamide and dimethylsulfoxide

Cyclic and square wave voltammetry (−1500 to 1500 mV) of {Mn[μ-(C₆H₅)₂NC₄O₃]₂[H₂O]₄}_n [manganese(II) diphenylaminosquarate] (1) and [Mn(μ-C₆H₅C₄O₃)(C₆H₅C₄O₃)(H₂O)₃]_n [manganese(II) phenylsquarate] (2) at a gold disk electrode in dimethylsulfoxide (DMSO) and dimethylformamide (DMF), reveal several couples attributable to both ligand and metal-based redox processes. For the manganese(II) phenylsquarate in DMF, the metal-based peaks are more numerous and readily discernible than in DMSO. In either of the solvents, the ligand-based peaks always occur at more positive or more negative potentials than the metal-based ones. In 1 and 2, Mn(II)/Mn(0), Mn(III)/Mn(II), Mn(IV)/Mn(III) and Mn(V)/Mn(IV) couples are observed. However, the manganese redox peaks appear at more negative potentials in 1.