Photoinduced ring-opening rearrangement of a radical cation of cyclobutane in CFCl 3 at low temperature: ESR observation

Abstract

ESR observation is described of a new type of reaction of alkane radical cations in solid matrices; the cyclobutane radical cation in CFCl 3 and in SF 6 suffers photoinduced ring opening followed by 1,3-hydride ion transfer to rearrange into the but-1-ene radical cation, which further photoisomerizes into the cis-but-2-ene radical cation. The results are compared with thermal ring opening reported for the cyclopropane radical cation to give the trimethylene radical cation CH 2CH 2CH 2 + in CFCl 2CF 2Cl. A possibility of hydride ion transfer to form CH 2CH 2CH 3 is discussed as an alternative interpretation of the spectrum assigned to the trimethylene radical cation.