Origin Band Shifts Upon Deuteration in the 280 nm Absorption System of Benzimidazole

Abstract

Five deuterated derivatives of benzimidazole have been prepared and their sharp 280 nm vapour phase electronic absorption spectra recorded. When hydrogen atoms bonded to carbon are substituted, the origin band shifts to higher energies by 29 cm^?1 per D atom, a value close to that found in benzene and some monosubstituted benzenes. When the hydrogen bonded to nitrogen is substituted, a much smaller shift is observed.