ETUDE ELECTROCHIMIQUE DE LA LABILITE DES COMPLEXES PARAMAGNETIQUES η5-CYCLOPENTADIENYLE η6-ARENE FER(I). REACTION D'ECHANGE DE L'ARENE PAR LE CYCLOPENTADIENE

Article abstract of DOI:10.1016/0022-328X(86)80104-8

The decomposition of neutral electrogenerated η⁵-cyclopentadienyl-η⁶-areneiron(I) is investigated.The cyclic voltammetry shows that the cationic precursors η⁵-CpFe^II+-η⁶-Ar are reduced in a one-electron transfer step followed by a chemical step which involves coordination of solvent molecules.The increasing stability of η⁵-C5H5Fe^I-η⁶-C6H6 follows the order of solvent used: acetonitrile or pyridine < dimethylformamide < acetone or methylene chloride.In acetonitrile, the fast replacement of C6H6 by donor ligands occurs via a postulated intermediate, the 17-electron complex η⁵-C5H5Fe^I(CH3C)2.Without donor ligands decomposition of η⁵-CpFe^I-η⁶-Ar leads to the corresponding ferrocenes, Cp2Fe^II.In the presence of cyclopentadiene the electrochemical activation allows replacement of the arene group of η⁵-CpFe^II+-η⁶-Ar by a cyclopentadienyl ligand.