DETECTION OF PHENYL-SUBSTITUTED RADICAL CATIONS DERIVED FROM CYCLOPENTYL-TYPE AND URAZOLE-TYPE AZOALKANES BY PULSE-RADIOLYSIS, INFLUENCE OFHETEROATOM SUBSTITUTION ON THE RADICAL-CATION REACTIVITIES

The radical cations of cyclopentane- and urazole-annelated azoalkanes and housanes were generated by pulse radiolysis and the transients cha racterized spectrally and kinetically by time-resolved optical monitor ing. For the bridgehead-substituted diphenyl derivatives of the cyclop entane-annelated azoalkane 1 and housane 2 only the corresponding prox imate 1,2 radical cation species were observed, generated from the ini tially formed and too short-lived (<1 mu s) distonic 1,3 radical catio n by 1,2-methyl migration, In contrast, for the corresponding urazole- annelated azoalkanes 4, the-initial distonic 1,3 radical cations 5(.+) were detected, and of these the methyl-substituted 5b(.+) deprotonate s to the radical 5b(.).