Structures and Mechanisms of the Carbonyl-ene Reaction between MOF-11 Encapsulated Formaldehyde and Propylene: An ONIOM Study

Abstract

Metal−organic framework structures containing formaldehyde (HCHO@MOF-11) and its interactions with propylene were investigated by density-functional (B3LYP/6−31G(d,p)) and ONIOM (B3LYP/6−31G(d,p):UFF) calculations. For comparison, the carbonyl-ene reaction of propylene and formaldehyde was also studied with Cu + alone as a catalyst. It was found that the metal−organic framework leads to an energy barrier of the reaction Δ E act of 24.1 kcal/mol. This compares to values of Δ E act of 34.4 kcal/mol for the uncatalyzed system and 6.4 kcal/mol if the reaction takes place with the Cu + alone. The carbonyl-ene reaction of propylene using HCHO@MOF-11 takes place in a single concerted reaction step. The Δ E act value for MOF-11 is similar to that obtained for the zeolite catalyzed reaction (Δ E act = 25.1 kcal/mol, HCHO@Na-faujasite/CH 3 CH=CH 2 ).