Electron transfer reactions of bis[dicarbonyl(pentamethylcyclopentadienyl)iron] with organic compounds

Abstract

[(C 5Me 5)Fe(CO) 2] 2 ( A) reacts with one equivalent of tetracyanoethylene (TCNE) and tetracyanoquinodimethane (TCNQ) to give the compounds {2[(C 5Me 5)Fe +(CO) 2]·TCNE 2−} ( B) and {2[(C 5Me 5)Fe +(CO) 2]·TCNQ 2−} ( D) respectively. The reaction of A with two equivalents of TCNE gives the polymeric compound [(C 5Me 5)Fe(CO) 2TCNE] n ( C) in which the TCNE 2− anion is coordinated to the metal through nitrogen of the CN group. Electronic, IR and ESR spectra indicate that compounds B and D are formed by two one-electron steps involving the rather elusive [(C 5Me 5)Fe(CO) 2 ] radicals. The electron transfer processes are discussed on the basis of the thermodynamic redox potentials of donor A and of two acceptors TCNE and TCNQ.