Scf-perturbational analysis of substituent effects in the dediazoniation of aryldiazonium ions

Abstract

A M.O. rationalization of the substituent effects on the rate constants for the dediazoniation of substituted aryldiazonium ions has been performed using SCF-perturbation theory. The total perturbation energies arising from a distortion of the Ar-N bonds reflect the substituent effects on the rate constants. The substituent effects are analysed by means of energy components characterising the role of the unperturbed electron density distribution, its relaxation via mixing of orbitals and the nuclear repulsion energy. The influences of the substituents are separated into σ and π contributions using energy increments for localised orbitals. These energy components of the perturbation energy correlate reasonably with the σ l and σ R + constants for the inductive and resonance effects, respectively, of the substituents.