Aqueous Phase Organometallic Catalysis Using (MeCp)2Mo(OH)(H2O)+. Intramolecular Attack of Hydroxide on Organic Substrates
journal contributionposted on 12.04.2004, 00:00 by Kerry L. Breno, Michael D. Pluth, Christopher W. Landorf, David R. Tyler
The hydrolysis of esters and difunctional ethers catalyzed by Cp‘2Mo(OH)(H2O)+ (1) (Cp‘ = η5-C5H4CH3) and the stoichiometric oxidation of CO to CO2 in the presence of 1 are described. These reactions, combined with the previously reported nitrile hydrations and phosphate esters hydrolyses catalyzed by 1, demonstrate that 1 is an effective homogeneous catalyst for hydration, hydrolysis, and oxidation reactions in aqueous solution under mild conditions (pH ∼7, ∼80 °C). Each reaction is proposed to proceed by intramolecular attack of the hydroxide ligand on a bound substrate. The intramolecular nature of the reaction is supported by the ester hydrolysis activation parameters (ΔH⧧ = 5.9 ± 0.7 kcal/mol and ΔS⧧ = −48 ± 9 eu), the lack of H/D exchange, and the significant increase (106−108) in the rate of hydrolysis over uncatalyzed hydrolysis.