QUADRICYCLANE AND NORBORNADIENE RADICAL CATIONS IN SILICALITE - COMPARISON WITH FREON MATRICES

The radical cation of nonbornadiene is produced by gamma radiolysis of nonbornadiene or quadricyclane in silicalite at 77 K. The bicyclo[3.2 .0]hepta-2,6-diene radical cation and the bicyclo[2.2.1]hepta-2,5-dien e-7-yl radical are observed at higher temperatures. The same radical c ation chemistry was recently examined by EPR in freon matrices, and di fferences with this EPR study in zeolites are discussed. Some zeolite sites must be able to stabilize higher electronic states of radical ca tions, enabling otherwise photochemical processes to be thermally acce ssible in zeolites.