Exchange of Hydrogen between a Platinum Surface and a Tertiary Amine: An ab Initio Molecular Dynamics Investigation

Abstract

The presence of a tertiary amine plays a role in accelerating the catalysis of ketones hydrogenation on a platinum surface covered by hydrogen. Ab initio molecular dynamics has been applied to achieve an atomistic understanding of this base effect. The interaction of trimethylamine with hydrogen adsorbed on a platinum nanoparticle has been simulated for 22 ps revealing that hydrogen increases its oscillatory modes upon interaction with the base therefore its activation. Nonetheless in the case of trimethylamine, competing interactions appear in the form of skeletal hydrogen (from the methyl group) interacting with the metal particle. Such interactions distract the action of the base and predominate at the end of the simulation. The interaction of the trimethylamine molecule with hydrogen adsorbed on platinum is compared to the corresponding interaction of the quinuclidine moiety of cinchonidine, which is the most widely applied chiral modifier for the platinum catalyzed enantioselective hydrogenations. Th...