Related Experiment Video
Updated: May 11, 2025

Multiscale Sampling of a Heterogeneous Water/Metal Catalyst Interface using Density Functional Theory and Force-Field Molecular Dynamics
Published on: April 12, 2019
Mechanistic Insight into Water Oxidation Catalysis by a Mononuclear Ruthenium Complex
Takahiko Kojima1, Tomoki Takaoka1, Yusuke Chiba1
1Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan.
Abstract:
A reaction mechanism of water oxidation involving a mononuclear RuIV-oxo complex (1) as an intermediate with use of (NH4)2[CeIV(NO3)6] (CAN) as an oxidant has been scrutinized to provide a clear view of O-O bond formation and O2 release. This work includes the spectroscopic and theoretical characterization of an end-on RuIII-superoxo complex (3), together with the crystallographic characterization of a side-on RuIV-peroxo complex (4) which should be in equilibrium with 3 in an aqueous solution. The formation of the RuV-oxo intermediate as a responsible species for the water oxidation was supported by a square wave voltammogram of 1 in an aqueous solution, showing an oxidation wave at +1.52 V (vs NHE) which is accessible with use of excess CAN through an electron-transfer equilibrium. Kinetic analysis and isotope labeling experiments supported a water nucleophilic attack (WNA) mechanism in the water oxidation. The stability of 3 as a product of WNA allowed us to detect it in aqueous solution. The diamagnetic character of 3 enabled the detailed kinetic investigation of O2-releasing from the intermediate to determine activation parameters. Herein, a new insight was gained into the O2 release from 3 as the final step of water oxidation by the mononuclear Ru catalyst.
More Related Videos
Related Concept Videos
Catalysis
Radical Oxidation of Allylic and Benzylic Alcohols
Introduction to Mechanisms of Enzyme Catalysis
Oxidative Cleavage of Alkenes: Ozonolysis
Ozone is a symmetrical bent molecule stabilized by a resonance structure.
Rate-Determining Steps
In a multistep reaction mechanism, one of the elementary steps progresses significantly slower than the others. This slowest step is called the rate-limiting step (or rate-determining step). A reaction cannot proceed faster than its slowest step, and hence, the rate-determining step limits the overall reaction rate.
The concept of rate-determining step can be understood from the analogy of a 4-lane freeway with a short-stretch of traffic-bottleneck caused due to...
Radical Autoxidation

