AbstractThe1H and13C n.m.r. spectra ofN‐methylated pyridine, pyridazine, pyrimidine and pyrazine andN,N‐dimethylated pyrimidine and pyrazine have been recorded and analysed. The change in the13C chemical shifts under the influence ofN‐methylation (Δδ) in the diazabenzenes could be predicted by the Δδ values of pyridine. A comparison of the Δδ values ofN‐methylation with those ofN‐protonation showed that both reactions have a