The relationship between carbon-13 substituent chemical shifts and proton coupling constants in aza-aromatic systems

Abstract

An equation which relates the ortho carbon-13 substituent chemical shift α-SCS in aza-aromatics to the ortho proton-proton coupling constant 3J(HH) in the corresponding carbocyclic compound is derived from experimental data. The implications for N-N bond fixation in diaza-aromatics are discussed. When the equation is applied to 2-substituted pyridines, an electronegativity parameter must be included to explain the results.