Dynamics with Explicit Solvation Reveals Formation of the Prereactive Dimer as Sole Determining Factor for the Efficiency of Ru(bda)L2 Catalysts

Abstract

This report describes all key steps in the O-O bond formation from two separated [RuV=O(bda)L2]+ cations to form the dinuclear [(bda)L2RuIV-O-O-RuIV(bda)L2]2+ in explicit solvent. The three steps involve the diffusion of the catalysts in the water phase, formation of the prereactive dimer, and the bond formation between the two catalysts. On the basis of the calculated parameters, we compute the rate constant of two catalysts with different L-ligands, isoquinoline and picoline, and the computed values are in excellent agreement with the experimental ones. The interaction of the axial ligands is key to the improved rates of the larger ligand, mainly by facilitating the formation of the prereactive dimer from the solvated monomer. By comparing the binding free energy of hydrophilic RuIV-OH and hydrophobic RuV=O, the hydrophobic driving force of RuV=O in this system has been estimated to 1 kcal mol-1.