15N‐13C spin coupling as a probe of electronic structure in benzenediazonium ions: INDO—SOS—MO calculations and steric inhibition of resonance

Abstract

AbstractThe magnitude of 1J(15N13C) in para‐substituted benzenediazonium ions has been used to assess the importance of the several resonance forms contributing to the ground state of the ion. From a comparison of values observed in 4‐nitro‐ and 4‐dimethylamino‐benzenediazonium ions and their respective 3,5‐dimethyl derivatives, it is concluded that diazo‐type structures are important only with strong electron‐releasing substituents in the aromatic ring. INDO–SOS–MO calculations indicate that the large and negative Fermi contact term dominates this interaction.