Organometallic peroxy radicals. 4. Electron spin resonance spectra of the radicals produced by reaction of organophosphorus(IV) and organoarsenic(IV) radicals with ¹⁷O-enriched oxygen

Abstract

It bas been shown that some tetra-coordinate phosphorus and arsenic radicals combine with oxygen to give peroxy radicals. The magnitude of the oxygen isotropic and anisotropic hyperfine coupling constants indicates that nearly all the unpaired spin is associated with the two oxygen nuclei with ca. 60% on the terminal oxygen. The large isotropic g-factors associated with Group VB peroxy radicals relative to alkylperoxy radicals is attributed to a small change in geometry of the peroxy function.The radicals with ap ∼ 9 G obtained during the reaction of photochemically generated tert-butoxy radicals with trialkylphosphites in the presence of oxygen are secondary species which appear to contain only one oxygen atom.

Radical Model of Arsenic(III) Toxicity: Theoretical and EPR Spin Trapping Studies

“…The proposed formation of the HO 2 −As complex as an intermediate for radical formation is attractive due to the inhibition of radical formation in the presence of SOD. Organoarsenic peroxy radicals have been generated and detected by EPR from the reaction of organoAs IV and O 2 , 50 and dimethylarsenic peroxy radicals (CH 3 ) 2 AsOO • have been implicated as reactive intermediates in oxidative damage to DNA. 51 Although the proposed mechanism of methyl radical formation from MMA III is hypothetical at this point, this warrants further investigation.…”