A B3LYP study on the C–H activation in propane by neutral and +1 charged low-energy platinum clusters with 2–6 atoms

The global optimization of neutral and +1 charged Pt n (n = 2–6) clusters were conducted at the B3LYP/LANL2DZ(f) level of theory. The lowest-energy structures of neutral Pt n (n = 3–6) clusters adopt an equilateral triangle, a tetrahedron, an edge-capped tetrahedron, and a prism structure, respectively. The insertion of Pt n (n = 2–6) into one of the central C–H bonds in propane, Pt n + C3H8 → H–Pt n –CH(CH3)2, was studied subsequently for selected low-energy Pt cluster structures. We found that the Pt n global minimum does not necessary make the most contribution to the catalyzed dehydrogenation of propane. For example, the prism structure in the septet electronic state is the global minimum of Pt6, yet the 5Pt6 edge-capped pyramid structure makes significantly more contribution to the activation of C–H bonds in propane. In sum, the energy barrier for the Pt2 + C3H8 → H–Pt2–CH(CH3)2 reaction is 33 kJ/mol; Pt3–6 have significantly lower barriers of 4–16 kJ/mol. The +1 charged Pt + n (n = 2–6) clusters are much more active towards propane than their neutral counterparts because of the large amount of energy (30–140 kJ/mol) released in the formation of the Pt + n –C3H8 reactant complex. A similar charge effect is also observed for the larger Pt10 + cluster