Reaction Mechanisms between (Cl-nacnac)Pt(H) and a Terminal Alkyne

On the basis of Templeton′s experiment (West, N. M.; et al. Organometallics 2008, 27, 5252), the mechanisms of the main and the side reactions between (Cl-nacnac)Pt(H) (Cl-nacnac: bis(N-aryl)- β-diiminate) and a terminal alkyne were investigated by density functional theory. Our study shows that the 1,2-insertion of t-BuC≡CH into the Pt―H bond generates the main products and that C―C bond formation is the rate-determining step. The 2,1-insertion of t-BuC≡CH into the Pt―H bond generates the by- products and alkyne insertion is the rate-determining step. Based on the mechanisms of the main and side reactions the presence of the main product and the by-product could be explained. We found that the main product is thermodynamically controlled while the side product is kinetically controlled.