Theoretical study of the potential-energy surface related to H2N+NS reaction: N2vs. H2 elimination

Abstract

The potential-energy surface related to the H₂N+NS reaction, which involves 13 intermediates and fragment products, as well as 14 transition structures has been fully characterized using both molecular orbital (MP2) and density functional theory (B3LYP) and the 6-311++G(d,p) basis set. Improved electronic energies have also been obtained using single-point coupled-cluster CCSD(T) calculations. The system is shown to have three different groups of products: N₂H+SH, N₂S+H₂ and N₂+H₂S and a rather complex reaction mechanism. Starting from H₂N+NS, several low-lying [H₂N₂S] isomers participate in the elimination of H₂ and N₂. The N₂ elimination appears to be favoured over other reaction channels in the destruction of NS. The standard enthalpies of formation of the most stable isomers have been estimated, Δ_fH₂₉₈^° in kJ mol^-1: H₂N–NS: 250, H₂N–S▷N: 262, NHNHS: 264, NHN–SH: 247 and NHSNH: 318.