Se-N interactions in selenohydroxylamine: a theoretical study

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.