Substituent effects on one-bond15N13C couplings inN,N-dimethylanilines and nitrobenzenes. Effect of steric inhibition of conjugation
摘要:
AbstractThe 1J(15N13C) values for a series of ring‐substituted N,N‐dimethylaniline‐15N derivatives and a series of nitrobenzene‐15N derivatives were measured from the 13C spectra. In the nitrobenzenes, small changes in 1J(15N13C) are attributed to the inductive effect of the substituents, since steric inhibition of conjugation has little effect on the magnitude of the coupling. In contrast, steric inhibition of nitrogen lone‐pair delocalization in N,N‐dimethylaniline derivatives markedly reduces the value of 1J(15N13C). Theoretical calculations of 1J(15N13C) values for the two series of compounds were made using standard INDO parameters and a ‘sum‐over‐states’ perturbation approach. Fair agreement between the calculated and experimental values is found.