title: Structure and Stability of Pentafluoroaniline and 4-Aminononafluorobiphenyl Radical Anions: Optically Detected Electron Paramagnetic Resonance, Time-Resolved Fluorescence, Time-Resolved Magnetic Field Effect, and Quantum Chemical Study.
abstract: Radical anions (RAs) are the key intermediates of the selective hydrodefluorination of polyfluoroarenes. We used the techniques of optically detected electron paramagnetic resonance (OD EPR), time-resolved fluorescence, time-resolved magnetic field effect (TR MFE), and the density functional theory to study the possibility of RAs formation from 4-aminononafluorobiphenyl (1) and pentafluoroaniline (2) and estimate their lifetimes and decay channels. To our knowledge, both RAs have not been detected earlier. We have registered the OD EPR spectrum for relatively stable in nonpolar solutions 1(-•) but failed to register the spectra for 2(-•). However, we have managed to fix the 2(-•) by the TR MFE method and obtained its hyperfine coupling constants. The lifetime of 2(-•) was found to be only a few nanoseconds. The activation energy of its decay was estimated to be 3.6 ± 0.3 kcal/mol. According to the calculation results, the short lifetime of 2(-•) is due to the RA fast fragmentation with the F(-) elimination from ortho-position to the amine group. The calculated energy barrier, 3.2 kcal/mol, is close to the experimental value. The fragmentation of 2(-•) in a nonpolar solvent is possible due to the stabilization of the incipient F(-) anion by the binding with the amine group proton.
authors.affiliation: †Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of Russian Academy of Science, 3 Institutskaya Street, Novosibirsk 630090, Russia.|‡Novosibirsk State University, 2 Pirogova Street, Novosibirsk 630090, Russia.
authors.forename: Vsevolod I
authors.initials: VI
authors.lastname: Borovkov
authors.affiliation: §N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of Russian Academy of Science, 9 Lavrentiev Avenue, Novosibirsk 630090, Russia.
authors.forename: Irina V
authors.initials: IV
authors.lastname: Beregovaya
authors.affiliation: §N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of Russian Academy of Science, 9 Lavrentiev Avenue, Novosibirsk 630090, Russia.
authors.forename: Lyudmila N
authors.initials: LN
authors.lastname: Shchegoleva
authors.affiliation: †Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of Russian Academy of Science, 3 Institutskaya Street, Novosibirsk 630090, Russia.
authors.forename: Svetlana V
authors.initials: SV
authors.lastname: Blinkova
authors.affiliation: †Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of Russian Academy of Science, 3 Institutskaya Street, Novosibirsk 630090, Russia.|‡Novosibirsk State University, 2 Pirogova Street, Novosibirsk 630090, Russia.
authors.forename: Dmitry A
authors.initials: DA
authors.lastname: Ovchinnikov
authors.affiliation: ∥Institute of Chemistry Saint Petersburg State University, 26 Universitetskii Prospect, Petrodvoretz, Saint-Petersburg 198504, Russia.
authors.forename: Larisa Yu
authors.initials: LY
authors.lastname: Gurskaya
authors.affiliation: §N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of Russian Academy of Science, 9 Lavrentiev Avenue, Novosibirsk 630090, Russia.
authors.forename: Vitaly D
authors.initials: VD
authors.lastname: Shteingarts
authors.affiliation: †Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of Russian Academy of Science, 3 Institutskaya Street, Novosibirsk 630090, Russia.|‡Novosibirsk State University, 2 Pirogova Street, Novosibirsk 630090, Russia.
authors.forename: Victor A
authors.initials: VA
authors.lastname: Bagryansky
authors.affiliation: †Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of Russian Academy of Science, 3 Institutskaya Street, Novosibirsk 630090, Russia.
authors.forename: Yuriy N
authors.initials: YN
authors.lastname: Molin
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry*; D000838:Anions / Q000737:chemistry; D001713:Biphenyl Compounds / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D005453:Fluorescence; D005609:Free Radicals / Q000737:chemistry; D060526:Magnetic Fields; D015394:Molecular Structure; D011789:Quantum Theory; D013997:Time Factors; D005464:Fluorobenzenes; D005466:Fluorocarbons
chemical_list: D000814:Aniline Compounds; D000838:Anions; D001713:Biphenyl Compounds; D005609:Free Radicals; C068134:2,3,4,5,6-pentafluoroaniline; D005464:Fluorobenzenes; D005466:Fluorocarbons