Redox properties of 17-electron thiolate complexes of cyclopentadienyl iron (III)

The redox electrochemistry of iron (III) thiolate complexes of the type [CpFe(dppe)-SR]PF6 R = CH3, C3K7, C6H5, p-C6H4Br and thiobenzothiazole has been examined by cyclic voltammetry, coulometry and spectroelectrochemistry methods. Four redox waves were observed in the range - 1.5 to + 1.5 V (S.C.E) in CH2Cl2. Around 0.0 V the-metal centered reduction Fe (III)-->Fe(II) process was observed, while that around +0.5V the wave observed was attributed to a ligand centered oxidation. Strongly irreversible waves of oxidation near 1.3 V were assigned to the oxidation of RSSR while a reduction wave also strongly irreversible at very high negative potential was attributed to the reduction of the RSSR free ligand, RSSR+2e-->2RS(-). The redox wave observed for the disulphides compounds are discussed in terms of a reductive elimination of RSSR. Chemical and electrochemical reduction of the complexes [CpFe(dppe)-SR]PF6 was accomplished by the color changes blue --> red-brown characteristic of the redox change 17e-->18e. (C) 1998 Elsevier Science Ltd. Al rights reserved.