Interaction of Y, Y2, Mo, and Mo2 with NH3. A Density Functional Study

Abstract

The interaction of Y, Y 2 , Mo, and Mo 2 with NH 3 is studied to understand the influence of the electronic configuration of the transition metal atoms and clusters on their reactions with ammonia. The interactions are investigated with the all-electron linear combination of Gaussian-type orbitals Kohn-Sham density functional theory (LCGTO-KS-DFT). The binding energies and harmonic frequencies characterize the equilibrium geometries. The reaction products investigated are MNH 3 , MNH, M 2 NH 3 , M 2 NH, and M 2 (NH) 2 . The binding energy indicates that the reaction of Y and Y 2 is possible. For Y, the stable products are YNH 3 and YNH with binding energies of 24.6 and 32.6 kcal/mol, respectively. For Y 2 , the stable products of the reaction are Y 2 NH 3 , Y 2 NH, and Y 2 (NH) 2 (binding energies of 13.9, 55.5, and 110.2 kcal/mol, respectively). For Mo, the stable product is MoNH 3 with a binding energy of 8.5 kcal/mol. For MoNH, the binding energies indicate that the reactants (Mo + NH 3 ) are more stable than the products (MoNH + H 2 ) by 9.8 kcal/mol. For the Mo 2 [NH 3 ] complex, the binding energy is 17.9 kcal/mol, in good agreement with the experimental value of 14 kcal/mol previously reported. For Mo 2 , there are no other stable products of the reaction because Mo 2 NH and Mo 2 (NH) 2 are less stable than the reactants (Mo 2 + NH 3 ) by 12.7 and 10.9 kcal/mol, respectively. The differences in the bonding are explained with molecular orbital pictures. For each metal, a relationship between the electronic configurations of the transition metals and the binding energies is reported.