Solvation and nucleophilic reactivity of 1,2,4-triazolate ion in acetonitrile–methanol mixtures

Abstract

The 1,2,4-triazolate ion is a stronger hydrogen-bond accepting base than 5-substituted 1,2,3-benzotriazolate ions. Partly because of this characteristic, the transition-state anion of the 1,2,4-triazolate ion reaction with ethyl iodide indicates the most significant hydrogen-bond accepting basicity of a transition-state anion so far observed. The PM3 atomic charge on the nitrogen atom at the 4-position of the 1,2,4-triazolate ion and the average PM3 atomic charge on the nitrogen atom at the 1- and 3-positions of 5-substituted 1,2,3-benzotriazolate ions make the most significant contribution to the basicity of the relevant anion. The significant basicity for the transition-state anion has been rationalized through an empirical correlation between the specific interaction enthalpy, Δ_tH_SI^AN→MeOH, and the PM3 atomic charge.