Jih Tzong Wang

ESR spectra and structure of the n-butane and n-hexane radical cations

Abstract Well-resolved ESR spectra of the n -butane and n -hexane radical cations have been generated, each spectrum showing a 1:2:1 triplet and a detailed substructure. The results are interpreted in terms of an a g singly occupied MO ( σ C—C, δC–H ax ) which is delocalized over the extended carbon chain (C 2h symmetry) and two axial hydrogens.

ESR evidence for the formation of the ring-opened cation CH2OCH2± from ethylene oxide

Abstract ESR results show that the radical cation formed from ethylene oxide in the solid state is the ring-opened 2-oxa-trimethylene cation with a symmetrical (C2ν) planar structure similar to that of the isoelectronic allyl radical. In contrast, the trimethylene oxide radical cation retains the ring structure of the parent molecule and its ESR parameters are characteristic of an oxygen-centred species.

13C Hyperfine interaction in the hexafluorobenzene radical anion

Abstract Naturally abundant 13 C satellites have been detected in the isotropic EPR spectrum of C 6 F − 6 , the 13 C coupling being 12.1 G The magnitude of this coupling does not support a nonplanar structure for C 6 F − 6 . Also, the value is more consistent with a σ ∗ than a π ∗ configuration in D 6h , symmetry.

A clarification of the factors governing the stability of rx- radical anions

It is stressed that RX−1 radical anions can bs formed even when the configuration and hybridization of the completely dissociated radical R· differ from that of R in the parent molecule RX. The necessary condition for RX-1 dissociation is derived and illustrated by means of potential energy diagrams.

The epr spectrum of C2F−4☆

Abstract The EPR spectrum of C2F−4 in methylcyclohexane-d14 is analysed and discussed. It is concluded that there is insufficient evidence to decide in favor of neither a π* or α* configuration.

A reassignments of the EPR spectrum attributed to the radical cation of 2,2,3,3-tetramethylbutane☆

Abstract The EPR spectrum of γ-irradiated 2,2,3,3-tetramethylbutane has been reinvestigated. Previous evidence for the radical cation Me 3 C −− CMe + 3 has been critically examined and it is concluded that a more satisfactory analysis can be made on the basis of the three neutral radicals − CH 2 CMe 2 CMe 3 , − CMe 2 CMe 3 and − CMe 3 .

The radical cation of 1,4-dihydropentalene and its photochemical formation from bicyclo [3.3.0] octa-2,6-diene-4,8-diyl cation

Abstract In contrast to recent claims by Rhodes and Glidewell, comparison of both ESR and electronic absorption spectra shows that the photoproduct of the recently characterized radical cation of bicyclo [3.3.0] octa-2,6-diene-4,8-diyl is identical to the 1,4-dihydropentalene radical cation, i.e. a linear conjugated tautomer of the former produced by two hydrogen shifts. Ab initio calculation indicate that the tetracyclic diyl radical cation postulated by Rhodes and Glidewell is inaccessible under their experimental conditions ( h ν ⩽ 2.2 eV).

E.s.r. evidence for the rearrangement at 77 K of ionized allylamine to the distonic radical cation ·CH2CH2CHNH2

The radical cation formed by radiolytic oxidation of prop-2-enylamine (allylamine) in Freon matrices at 77 K is the 3-iminiopropyl distonic species (3-iminium-1-propyl radical) resulting from a 1,2-hydrogen shift in the parent cation.

E.s.r. evidence for deconjugation in the tetramethylurea radical cation

Photobleaching and other experiments show that the radical species generated on γ-irradition of Freon solutions of tetramethylurea is the parent radical cation and not the dimethylaminyl radical assigned previously; the e.s.r. parameters and other properties of this cation are consistent with a 2A′ nitrogen-centred radical formed by twisting one of the NMe2 groups perpendicular to the molecular plane.

Chlorofluoroalkyl radical rearrangements mediated by electron donors. An e.s.r. study in freon matrices

E.s.r. studies reveal that the CF2ClĊFCl radical ordinarily produced in γ-irradiated CF2ClCFCl2 solid solutions can rearrange to CF3ĊCl2 in the presence of amines with low ionization potentials, suggesting that this unexpected radical isomerization proceeds through chlorofluoroalkyl carbanionic species formed reversibly by electron transfer.