Synthesis, Electrochemistry, and Reactivity of Cerium(III/IV) Methylene-Bis-Phenolate Complexes

• DOI: 10.1021/ic400202r
• Publication Date: 2013-04-26T18:20:04Z
• Authors: Brian D. Mahoney; Nicholas A. Piro; Patrick J. Carroll; Eric J. Schelter
• Keywords: Models, Molecular; Molecular Structure; Phenol; Organometallic Compounds; Cerium; Electrochemical Techniques; Crystallography, X-Ray; 01 natural sciences; 0104 chemical sciences

A series of cerium complexes containing a 2,2'-methylenebis(6-tert-butyl-4-methylphenolate) (MBP(2-)) ligand framework is described. Electrochemical studies of the compound [Li(THF)2Ce(MBP)2(THF)2] (1) reveal that the metal based oxidation wave occurs at -0.93 V vs Fc/Fc(+). This potential demonstrates significant stabilization of the cerium(IV) ion in the MBP(2-) framework with a shift of ∼2.25 V from the typically reported value for the cerium(III/IV) couple of E°' = +1.30 V vs Fc/Fc(+) for Ce(ClO4)3 in HClO4 solutions. Compound 1 undergoes oxidation to form stable cerium(IV) species in the presence of a variety of common oxidants. The coordination of the redox-active ligands 2,2'-bipyridine and benzophenone to 1 result in complexes in which no apparent metal-to-ligand charge transfer occurs and the cerium ion remains in the +3 oxidation state.