Related Experiment Video
Updated: May 23, 2026

Multiscale Sampling of a Heterogeneous Water/Metal Catalyst Interface using Density Functional Theory and Force-Field Molecular Dynamics
Published on: April 12, 2019
Oxygen kinetic isotope effects upon catalytic water oxidation by a monomeric ruthenium complex
Alfredo M Angeles-Boza1, Justine P Roth
1Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, USA.
Abstract:
Oxygen isotope fractionation is applied for the first time to probe the catalytic oxidation of water using a widely studied ruthenium complex, [Ru(II)(tpy)(bpy)(H(2)O)](ClO(4))(2) (bpy = 2,2'-bipyridine; tpy = 2,2';6",2"-terpyridine). Competitive oxygen-18 kinetic isotope effects ((18)O KIEs) derived from the ratio of (16,16)O(2) to (16,18)O(2) formed from natural-abundance water vary from 1.0132 ± 0.0005 to 1.0312 ± 0.0004. Experiments were conducted with cerium(IV) salts at low pH and a photogenerated ruthenium(III) tris(bipyridine) complex at neutral pH as the oxidants. The results are interpreted within the context of catalytic mechanisms using an adiabatic formalism to ensure the highest barriers for electron-transfer and proton-coupled electron-transfer steps. In view of these contributions, O-O bond formation is predicted to be irreversible and turnover-limiting. The reaction with the largest (18)O KIE exhibits the greatest degree of O-O coupling in the transition state. Smaller (18)O KIEs are observed due to multiple rate-limiting steps or transition-state structures which do not involve significant O-O motion. These findings provide benchmarks for systematizing mechanisms of O-O bond formation, the critical step in water oxidation by natural and synthetic catalysts. In addition, the measurements introduce a new tool for calibrating computational studies using relevant experimental data.
More Related Videos
Related Concept Videos
Oxidative Cleavage of Alkenes: Ozonolysis
Ozone is a symmetrical bent molecule stabilized by a resonance structure.
Catalysis
Catalysis
Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
Oxidation of Alkenes: Syn Dihydroxylation with Potassium Permanganate
Radical Oxidation of Allylic and Benzylic Alcohols

