title: Homoleptic cerium(III) and cerium(IV) nitroxide complexes: significant stabilization of the 4+ oxidation state.
abstract: Electrochemical experiments performed on the complex Ce(IV)[2-((t)BuNO)py]4, where [2-((t)BuNO)py](-) = N-tert-butyl-N-2-pyridylnitroxide, indicate a 2.51 V stabilization of the 4+ oxidation state of Ce compared to [(n)Bu4N]2[Ce(NO3)6] in acetonitrile and a 2.95 V stabilization compared to the standard potential for the ion under aqueous conditions. Density functional theory calculations suggest that this preference for the higher oxidation state is a result of the tetrakis(nitroxide) ligand framework at the Ce cation, which allows for effective electron donation into, and partial covalent overlap with, vacant 4f orbitals with δ symmetry. The results speak to the behavior of CeO2 and related solid solutions in oxygen uptake and transport applications, in particular an inherent local character of bonding that stabilizes the 4+ oxidation state. The results indicate a cerium(IV) complex that has been stabilized to an unprecedented degree through tuning of its ligand-field environment.
authors.affiliation: P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States.
authors.forename: Justin A
authors.initials: JA
authors.lastname: Bogart
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Lewis
authors.forename: Scott A
authors.initials: SA
authors.lastname: Medling
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Piro
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Carroll
authors.forename: Corwin H
authors.initials: CH
authors.lastname: Booth
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Schelter