Oxidation State Ambiguities in Cerium Organometallics- A Computational Approach

Seven cerium organometallic systems are studied using both density functional theory and multiconfigurational techniques in order to better understand the oxidation state of the metal in each of these systems. These calculations show that in formally Ce(IV) organometallic systems with electron-rich, carbon-based ligands the total number of Ce 4f electrons is closer to the formal value of a Ce(III) system, rather than that of a Ce(IV) system. However, there remains a clear distinction between the Ce(III) and Ce(IV) f electron density: a localised f electron being found for Ce(III) system a delocalised f density is identified for the formally Ce(IV) systems. The calculations carried out have been used to rationalise the apparantly contradictory experimental data on the oxidation state of Ce in cerocene, to analyse the claims that cerocene might represent a molecular Kondo system, to rationalise the variable energy photoelectron spectrum of CeCp3 and to speculate about the possibility of synthesising CeCp2X compounds.