An electron spin resonance study of some aryl cobalt nitroxides
- 1 January 1971
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society B: Physical Organic
- p. 1059-1064
- https://doi.org/10.1039/j29710001059
Abstract
The pentacyanocobaltate(II) anion, [·Co(CN)5]3– reduces aromatic nitro-compounds and thereupon, behaving like a free radical, adds to aromatic nitroso-compounds to give aryl pentacyanocobalt nitroxide radical-anions, [(NC)5Co–N(Ar)–O·]3–, which have been characterised by their e.s.r. spectra in which the hyperfine splittings due to 14N (I= 1) and 59Co (I= 7/2) are dominant. Several spectra have been analysed and the influence of substituents in the aromatic ring on the aN,aCo, and aH splitting constants and on the g factors is discussed. Cobalt(II)–dimethylglyoxime complexes, Co(dmg)2XY, also react under nitrogen with aromatic nitroso-compounds and with highly chlorinated aromatic nitro-compounds to give free radicals identifiable by e.s.r. At pH 7 the cobalt(II) complex reduces ArNO to the radical (ArNHO·), at pH 8–9 there is also formed an aryl cobalt nitroxide [X(dmg)2Co–N(Ar)–O·] for which aN=aCo(approx.), and at pH 12 the signal corresponds to the radical-anion (Ar–N–O·)–.Keywords
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