Theoretical investigation of the mechanisms of reactions of H2CN and H2SiN with NO.

The mechanisms of the reaction of H2XN (X = C, Si) with NO were studied at the level CCSD(T)/aug-cc-PVTZ//B3LYP/6-31++G(d,p). The results indicate that there are two most favorable reaction pathways in the reaction H2CN + NO that have similar energy barriers; these two pathways lead to the formation of HCN + HNO (P1) and H2CO + N2 (P3), with the calculated barriers 11.1 and 10.2 kcal/mol, respectively, with respect to the reactants (H2CN + NO). In the reaction H2SiN + NO the difference of the barriers in these two analogous pathways becomes large, and the preferable pathway shifts to the production of H2SiO + N2 (P3s), which has no barrier with respect to the reactants (H2SiN + NO). A direct reduction of NO into a stable and nontoxic nitrogen molecule with no energy input becomes possible. As a consequence, H2SiN might be an effective reagent to convert the reactive and toxic NO into a benign gas N2 in several NO-producing combustion systems. We offer a possible explanation of the differences between H2CN and H2SiN toward NO as well as the calculated potential energies for these reactions.