Se–N interactions in selenohydroxylamine: a theoretical study

Abstract

The potential energy surfaces of thiohydroxylamine HS–NH2, 1, and selenohydroxylamine HSe–NH2, 2, have been searched, using ab initio and density functional methods, to study the conformational preferences. There are two minima on the path of rotation around the Se–N bond in 2. High accuracy G2MP2 calculations showed that the Se–N rotational barrier in 2 is 5.41 kcal mol−1, which is 1.16 kcal mol−1 less than the S–N rotational barrier in 1. The inversion around N in 1 and 2 goes through low energy barriers of 1.79 and 2.44 kcal mol−1 at the same level respectively. Charge analysis using the natural population analysis (NPA) method has been performed to understand the electronic factors responsible for the observed trends in the Se–N interactions. The strength of the negative hyperconjugation in 2 has been estimated using natural bond orbital (NBO) analysis and by studying the substituent effect.