New individual iminoxyl radicals

Conclusions We synthesized a series of individual 2,2,6,6-tetramethyl-1-oxyl-4-piperidyl diamides of carboxylic acids and dicarbamates.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2148–2149, September, 1968.     

NMR spectra of iminoxyl radicals

NMR spectra of iminoxyls and the corresponding amines are used to calculate the paramagnetic shifts in the free radicals, which are used to calculate the constants a _i for the hyperfine interactions with the protons in the radicals. The a _i for the -protons are negative, while those for the -protons are positive. The constants are discussed in relation to a simple model based on propagation of spin density via bonds by spin polarization and hyperconjugation. The spatial structure of the radicals is also discussed.     

Electron transfer between two stable radicals

Electron spin resonance (ESR) is a sensitive tool to detect the electron-transfer processes in some specified systems from the change of the ESR signals. In this paper, the interaction between poly(N,N-dimethylaniline) (PDMA) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) was investigated by ESR spectra based on the stability of their radicals in ethanol. It is shown that an electron-transfer process occurs from nitrogen atoms of PDMA molecules to those of DPPH molecules which makes PDMA form more stable radical cations and eliminates the radicals on DPPH.     

ESR study of nitro-substituted iminoxyl radicals

Iminoxyl radicals involved in the homolytic oxidation of nitrolic acids, with the general formula (NO₂)RC=NO^., have been detected by means of ESR. In the presence of a strong acid, the ESR spectra of the radical (NO₂)₂C=NO^. exhibits alternation of the line widths, owing to syn-anti isomerization.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1513–1516, July, 1991.     

Low-temperature NMR investigation of iminoxyl radicals

By analysis of proton magnetic resonance spectra recorded at 4.2 and 3 K, the isotropic and anisotropic constants for the coupling of the unpaired electron with all the protons were determined for two investigated radicals. On the basis of these results, conclusions were reached on the spin density distribution and on the participation of the unpaired electron in hydrogen bond formation.We express our sincere gratitude to I. F. Shchegolev for useful discussions.     

Reaction of iminoxyl radicals with triphenylmethylcarbonium salts

Russian Chemical Bulletin -