14N nuclear quadrupole resonance in carbazoles

Nitrogen-14 nuclear quadrupole resonance frequencies at 77 K are reported for a series of carbazole compounds including N-vinylcarbazole. Differences in charge distribution between pyrrole and carbazole are explained on the basis of delocalization of pi electrons. Effects of the aldehyde and vinyl groups on charge distribution are discussed. Sigma bond polarization between the pyrrole nitrogen and the nitroso nitrogen toward the pyrrole nitrogen exists in N-nitrosocarbazole.