title: Well-Known Mediators of Selective Oxidation with Unknown Electronic Structure: Metal-Free Generation and EPR Study of Imide-N-oxyl Radicals.
abstract: Nitroxyl radicals are widely used in chemistry, materials sciences, and biology. Imide-N-oxyl radicals are subclass of unique nitroxyl radicals that proved to be useful catalysts and mediators of selective oxidation and CH-functionalization. An efficient metal-free method was developed for the generation of imide-N-oxyl radicals from N-hydroxyimides at room temperature by the reaction with (diacetoxyiodo)benzene. The method allows for the production of high concentrations of free radicals and provides high resolution of their EPR spectra exhibiting the superhyperfine structure from benzene ring protons distant from the radical center. An analysis of the spectra shows that, regardless of the electronic effects of the substituents in the benzene ring, the superhyperfine coupling constant of an unpaired electron with the distant protons at positions 4 and 5 of the aromatic system is substantially greater than that with the protons at positions 3 and 6 that are closer to the N-oxyl radical center. This is indicative of an unusual character of the spin density distribution of the unpaired electron in substituted phthalimide-N-oxyl radicals. Understanding of the nature of the electron density distribution in imide-N-oxyl radicals may be useful for the development of commercial mediators of oxidation based on N-hydroxyimides.
authors.affiliation: N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences , 119991 Leninsky Prospekt 47, Moscow, Russian Federation.
authors.forename: Igor B
authors.initials: IB
authors.lastname: Krylov
authors.affiliation: Department of Physical Chemistry of Fossil Fuels In POCC, National Academy of Sciences of Ukraine Naukova st. 3a, Lviv 79053, Ukraine.
authors.forename: Mykhailo O
authors.initials: MO
authors.lastname: Kompanets
authors.affiliation: Department of Physical Chemistry of Fossil Fuels In POCC, National Academy of Sciences of Ukraine Naukova st. 3a, Lviv 79053, Ukraine.
authors.forename: Katerina V
authors.initials: KV
authors.lastname: Novikova
authors.affiliation: Department of Physical Chemistry of Fossil Fuels In POCC, National Academy of Sciences of Ukraine Naukova st. 3a, Lviv 79053, Ukraine.
authors.forename: Iosip O
authors.initials: IO
authors.lastname: Opeida
authors.affiliation: Department of Physical Chemistry of Fossil Fuels In POCC, National Academy of Sciences of Ukraine Naukova st. 3a, Lviv 79053, Ukraine.
authors.forename: Olga V
authors.initials: OV
authors.lastname: Kushch
authors.affiliation: N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences , 119991 Leninsky Prospekt 47, Moscow, Russian Federation.
authors.forename: Boris N
authors.initials: BN
authors.lastname: Shelimov
authors.affiliation: N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences , 119991 Leninsky Prospekt 47, Moscow, Russian Federation.
authors.forename: Gennady I
authors.initials: GI
authors.lastname: Nikishin
authors.affiliation: UFIP CNRS UMR 6286, Mechanism and regulation of DNA repair team, Université de Nantes , 2 rue de la Houssinière, 44322, Nantes, France.
authors.forename: Dmitri O
authors.initials: DO
authors.lastname: Levitsky
authors.affiliation: N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences , 119991 Leninsky Prospekt 47, Moscow, Russian Federation.
authors.forename: Alexander O
authors.initials: AO
authors.lastname: Terent'ev