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, C₃H₇, 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 + 1.5V (S.C.E) in CH₂Cl₂. Around 0.0 V the metal centered reduction Fe (III)→Fe (II) process was observed, while that around +0.5 V 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.