title: Experimental and theoretical studies of the redox potentials of cyclic nitroxides.
abstract: The redox potentials of 25 cyclic nitroxides from four different structural classes (pyrrolidine, piperidine, isoindoline, and azaphenalene) were determined experimentally by cyclic voltammetry in acetonitrile, and also via high-level ab initio molecular orbital calculations. It is shown that the potentials are influenced by the type of ring system, ring substituents and/or groups surrounding the radical moiety. For the pyrrolidine, piperidine, and isoindolines there is excellent agreement (mean absolute deviation of 0.05 V) between the calculated and experimental oxidation potentials; for the azaphenalenes, however, there is an extraordinary discrepancy (mean absolute deviation of 0.60 V), implying that their one-electron oxidation might involve additional processes not considered in the theoretical calculations. This recently developed azaphenalene class of nitroxide represents a new variant of a nitroxide ring fused to an aromatic system and details of the synthesis of five derivatives involving differing aryl substitution are also presented.
authors.affiliation: Australian Research Council Centre of Excellence for Free Radical Chemistry and Biotechnology, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland, 4001, Australia.
authors.forename: James P
authors.initials: JP
authors.lastname: Blinco
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Hodgson
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Morrow
authors.forename: James R
authors.initials: JR
authors.lastname: Walker
authors.forename: Geoffrey D
authors.initials: GD
authors.lastname: Will
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Coote
authors.forename: Steven E
authors.initials: SE
authors.lastname: Bottle
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D000465:Algorithms; D001372:Aza Compounds / Q000737:chemistry; D003497:Cyclic N-Oxides / Q000737:chemistry*; D004563:Electrochemistry; D054833:Isoindoles / Q000737:chemistry; D008962:Models, Theoretical; D010084:Oxidation-Reduction; D010880:Piperidines / Q000737:chemistry; D011759:Pyrrolidines / Q000737:chemistry
chemical_list: D000097:Acetonitriles; D001372:Aza Compounds; D003497:Cyclic N-Oxides; D054833:Isoindoles; D010880:Piperidines; D011759:Pyrrolidines; C032727:piperidine; C032519:pyrrolidine; C032159:acetonitrile