Photolysis of Reluctant Azoalkanes. Effect of Structure on Photochemical Loss of Nitrogen from 2,3-Diazabicyclooct-2-ene Derivatives

Article abstract of DOI:10.1021/ja00362a015

Azoalkanes containing the bicyclo<2.2.2>skeleton often prove to be remarkable stable toward loss of nitrogen.These derivatives of 2,3-diazabicyclo<2.2.2>oct-2-ene (DBO) also exhibit fluorescence whose lifetime extends to 600 ns.This paper is an attempt to understand the effect of fused rings and bridgehead substituents on the photochemical and photophysical properties of DBO.The main factor controlling quantum yields of nitrogen is a 6-11 kcal mol^-1 activation barrier that differs for the singlet and triplet states and that seems to mimic the barrier to ground-state deazatization.The product distribution for DBO derivatives is rationalized on the basis of interconverting singlet 1,4-biradicaloids.