Computational design of metal-free catalysts for catalytic hydrogenation of imines.

Using MeN=CMe(2) as an imine model, computational chemistry has been applied to design metal-free hydrogenation catalysts. The implementation includes designing proper electronic structures to split H(2) and building appropriate chemical scaffolds to prevent possible side reactions which may deactivate the catalysts. Interestingly, the designed catalysts bear resemblances to the well-known metal-ligand bifunctional hydrogenation catalysts in terms of both the activation principle and the hydrogenation mechanisms. The hydrogenations catalyzed by the designed catalysts proceed via two major steps, hydrogen activation and hydrogen transfer. The predicted energetics for completing the catalytic cycles indicate that these reactions have feasible kinetics and thermodynamics for experimental realizations under ambient conditions. We also showed how to improve the catalysis by using the "cooperative effect" and the non-bonding interactions. The reported catalysts can be the targets for experimental synthesis. The strategy can be borrowed to design similar catalysts.