Electrochemical reduction of MnO4-, TcO4- and ReO4-in organic solvents

Polarographic and controlled potential coulometric studies on permanganate, pertechnetate and perrhenate in organic solvents yield a 1-electron transfer as first reduction step; the half-wave potentials vs S.C.E. obtained in solutions of acetonitrile are Esub(1/2) = - 0.60 V, - 1.74 V and - 2.30 V, respectively. The limiting ionic conductivities of MnO4-, TcO4- and ReO4- are determined. The reversibility of the electrode processes is described in terms of the a.c. efficiences. Dark green [(CH3)4N]2MnO4, violet [(CH3)4N]2TcO4 and olive green [(CH3)4N]2ReO4 can be deposited on a platinum electrode as slightly soluble crystalline products by controlled potential electrolytic reduction of MnO4-, TcO4- and ReO4- in acetonitrile. (author)