E. P. Ivakhnenko

Reaction of 1H-1-oxo-2,4,6,8-tetrakis(tert-butyl)phenoxazine with certain group II-IV metals

Conclusions1.In the reaction of 1H-1-oxo-2,4,6,8-tetrakis(tert-butyl)phenoxazine with amalgams of the II–IV group metals, paramagnetic complexes are formed of mono-, bi- and triradical types, according to the nature of the reacting metal.2.Monoradical complexes with Al are formed as a result of successive hydrolysis of the triradical by traces of moisture.

Free radicals formed in the reaction of 1H-1-oxo-2,4,6,8-tetrakis(tert-butyl)phenoxazine and 1-hydroxy-2,4,6,8-tetrakis(tert-butyl)phenoxazinyl radical with certain organometallic compounds

Conclusions1.1H-1-Oxo-2,4,6,8-tetrakis(tert-butyl)phenoxazine undergoes ligand exchange reactions and behaves as a spin trap for metal-centered radicals, as a result of which stable paramagnetic complexes are formed with delocalization of the unpaired electron in the organic ligand.2.Paramagnetic complexes are also formed as the result of a reaction between potassium salt (IA) and triphenyl-tin and triphenyl-lead monochlorides.

Synthesis, isolation, and EPR spectra of the stable radical 1-hydroxy-2,4,6,8-tetrakis(tert-butyl)-10-phenoxazinyl

ConclusionStable 1-oxy-2,4,6,8-tetrakis(tert-butyl)-10-phenoxazinyl radical was isolated in the pure state. Its EPR spectra and chemical properties were studied.

Investigation of the reaction of 1,2,3-trimethyl-2-phenylbenzimidazoline with dehydrogenating reagents by EPR spectroscopy

The reaction of 1,2,3-trimethyl-2-phenylbenzimidazoline with a number of reagents that manifest dehydrogenating properties with respect to benziraidazolines was studied by EPR spectroscopy. These reagents convert 1,2,3-trimethyl-2-phenylbenzimidazoline to a relatively stable cation radical. The mechanism of the dehydrogenation of benzimidazolines is discussed taking into account the established facts.

Evolution of hydrogen in the reaction of hydroheteroaromatic compounds with dehydrogenating agents

The yields of molecular hydrogen in the reactions of benzimidazolines 1,2-dihydropyrimidines with a number of dehydrogenating agents have been determined. The formation of hydrogen is due to breakdown of the cation-radicals of the hydrohetarenes formed in the first stage of the reactions. The EPR spectrum of the cation-radical from 1,3-dimethyl-2-phenylbenzimidazoline has been obtained.

Free radicals and radical anions in a series of telluroxanthene derivatives

In the one-electron reduction of telluroxanthyl or telluroxanthone perchlorates, stable 9-aryltelluroxanthyl radicals and telluroxanthone radical anion are formed. An EPR study of the distribution of spin density in such radicals gives evidence that the nature of the heteroatoms in the xanthyl fragments has an insignificant influence on the distribution of the spin density.

Stable biradical in the benzimidazoline series, containing two cation-radical fragments with strong exchange interactions

A large number of uncharged stable biradicals are known [i]; there have been practically no reports, however, of biradicals containing two cation-radical fragments [bi(cationradicals)]. The only reported examples of radicals of this type have been polymeric viologens containing two or more unpaired electrons, in which the cation-radical functional groups are composed of nonaromatic y,y-dipyridylidene units [2]~ The exchange interaction between the unpaired electrons in this class of radicals is negligible; thus, their EPR spectra do not differ from the spectra of the corresponding viologen monoradicals. Viologenic biand poly(cation-radicals) are formed upon reduction of polypyridinium salts [2]. It is assumed that two-electron oxidation of compounds of the type R-X-R, in which the R groups are more readily ionized than the bridging group X, should provide a more general method for the preparation of hi(cation-radicals). We succeeded in carrying out this type of reaction in the case of 1,4-di(l,2,3-trimethylbenzimidazolinyl-2)benzene (I), * which contains two benzimidazoline functional groups linked by a nonconjugating p-phenylene bridge.

Synthesis, Isolation, and ESR Spectra of a Stable 1‐Hydroxy‐2,4,6,8‐tetra‐tert‐butyl‐10‐phenoxazinyl Radical.

The phenoxazinyl radical (III) is prepared from di-tert-butylaminophenol (I) and di-tert-butyl-o-quinone (II), together with the phenoxazinone (IV).