Theoretical studies on the conformations of selenamides

Abstract

Ab initio HF/6-31+G*, MP2/6-31+G*, B3LYP/6-31+G* level calculations have been performed on HSe-NH 2 to estimate the Se-N rotational barriers and N-inversion barriers. Two conformers have been found with syn and anti arrangement of the NH 2 hydrogens with respect to Se-H bond. The N inversion barriers in selenamide are 1⋅65, 2⋅47, 1⋅93 kcal/mol and the Se-N rotational barriers are 6⋅58, 6⋅56 and 6⋅12 kcal/mol respectively at HF/6-31+G*, MP2/6-31+G* and B3LYP/6-31+G* levels respectively. The n N → σ * Se-H negative hyperconjugation is found to be responsible for the higher rotational barriers.