Electrochemical behaviour and chemical oxidation study of the thio- and phosphido-bridge binuclear iron complexes

Abstract

The electrochemical behaviour of thio and phosphido complexes of iron(I): Fe 2XY(CO) 6 n L n (X = Y = SR, PR 2 and X = SR, Y = PR 2, L = PR 3) has been studied on platinum and mercury electrodes, in organic solvent. These complexes are reduced in a two-electron irreversible process. A large difference is observed between their oxidation potentials on mercury and platinum electrodes; this is ascribed to the formation of a mercury complex in which mercury is inserted into the metalmetal bond. In oxidation on platinum electrodes, two mono-electronic waves are observed. The influece of the ligand basicity on the cathodic E 1 2 values is discussed. A parallel shift is observed between the E 1 2 and the IR ν(CO) of the totally symmetrical mode. Chemical oxidation of the complexes shows that the dications cannot be isolated, and leads to isolation of the following species: [FeP(CH 3) 2(CO) 3] 2AgNO 3, [FeSCH 3(CO) 2P(CH 3) 3] 2(NO 3) 2, {[FeSCH 3(CO) 2P(CH 3) 3] 2F} PF 6, where NO 3 − and F − act as ligands.