On the Acid-Base Mechanism for Ruthenium Water Oxidation Catalysts
We present a detailed theoretical study of the pathway for water oxidation in synthetic ruthenium-based catalysts. As a first step, we consider a recently discovered single center catalyst, where experimental observations suggest a purely single-center mechanism. We find low activation energies (<...
| Main Authors: | , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
American Chemical Society
2012
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| Online Access: | http://hdl.handle.net/1721.1/69558 https://orcid.org/0000-0001-7111-0176 |
| Summary: | We present a detailed theoretical study of the pathway for water oxidation in synthetic ruthenium-based catalysts. As a first step, we consider a recently discovered single center catalyst, where experimental observations suggest a purely single-center mechanism. We find low activation energies (<5 kcal/mol) for each rearrangement in the catalytic cycle. In the crucial step of O−O bond formation, a solvent water acts as a Lewis base and attacks a highly oxidized RuV=O. Armed with the structures and energetics of the single-center catalyst, we proceed to consider a representative Ru-dimer which was designed to form O2 via coupling between the two centers. We discover a mechanism that proceeds in analogous fashion to the monomer case, with all the most significant steps occurring at a single catalytic center within the dimer. This acid−base mechanism suggests a new set of strategies for the rational design of multicenter catalysts: rather than coordinating the relative orientations of the subunits, one can focus on coordinating solvation-shell water molecules or tuning redox potentials. |
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