Water Participation in Catalysis: An Atomistic Approach to Solvent Effects in the Catalytic Isomerization of Allylic Alcohols

Abstract

We study the intermediate of the reaction between a ruthenium complex and 1-propen-3-ol in water using an atomistic approach for gaining information about the conformation and dynamics of complex molecules in aqueous solution, which combines density-functional-theory-based ab initio molecular dynamics and neutron scattering data based on empirical potential structure refinement simulations. We apply our method to the study of the water-soluble η2-allylic complex [RuCp(exo-η2- CH2 CH−CH2−OH)(PTA)2]+ (2) (PTA = 1,3,5-triaza-7- phosphaadamantane), an important intermediate in the isomerization of 1-propen-3-ol into propanal catalyzed by {RuCp(H2O- κO)(PTA)2}+. We identify the factors responsible for the stabilization of a specific conformer of 2 in water solution and we examine the involvement of water molecules in the formation of this species. In particular, we show that long-lived (ca. 10 ps) bonded chains of water molecules play a crucial role in influencing the conformation and, potentially, the chemical reactivity of 2.