A comparative computationally study about the defined m(II) pincer hydrogenation catalysts (m=fe, ru, os)

The mechanism of acetonitrile and methyl benzoate catalytic hydrogenation using pincer catalysts M(H)<inf>2</inf>(CO)[NH(C<inf>2</inf>H<inf>4</inf>PiPr<inf>2</inf>)<inf>2</inf>] (1M) and M(H)(CO)[N(C<inf>2</inf>H<inf>4</inf>PiPr<inf>2</inf>)<inf>2</inf>] (2M) (M=Fe, Ru, Os) has been computed at various levels of density functional theory. The computed equilibrium between 1Fe and 2Fe agrees perfectly with the experimental observations. On the basis of the activation barriers and reaction energies, the best catalysts for acetonitrile hydrogenation are 1Fe/2Fe and 1Ru/2Ru, and the best catalysts for methyl benzoate hydrogenation are 1Ru/2Ru. The best catalysts for the dehydrogenation of benzyl alcohol are 1Ru/2Ru. It is to note that the current polarizable continuum model is not sufficient in modeling the solvation effect in the energetic properties of these catalysts as well as their catalytic properties in hydrogenation reaction, as no equilibrium could be established between 1Fe and 2Fe. Comparison with other methods and procedures has been made.