4.7 Article

Experimental and Theoretical Study of CO2 Insertion into Ruthenium Hydride Complexes

Journal

INORGANIC CHEMISTRY
Volume 55, Issue 4, Pages 1623-1632

Publisher

AMER CHEMICAL SOC
DOI: 10.1021/acs.inorgchem.5b02556

Keywords

-

Funding

  1. Global Climate and Energy Program at Stanford
  2. National Science Foundation [NSF-CHE 1213403]
  3. Center for Electrocatalysis, Transport Phenomena, and Materials (CETM) for Innovative Energy Storage, an Energy Frontier Research Center - U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences [DE-SC00001055]
  4. Center for Molecular Analysis and Design (CMAD) fellowships
  5. Direct For Mathematical & Physical Scien
  6. Division Of Chemistry [1213403] Funding Source: National Science Foundation

Ask authors/readers for more resources

The ruthenium hydride [RuH(CNN)(dppb)] (1; CNN = 2-aminomethyl-6-tolylpyridine, dppb = 1,4-bis(diphenylphosphino)butane) reacts rapidly and irreversibly with CO2 under ambient conditions to yield the corresponding Ru formate complex 2. In contrast, the Ru hydride 1 reacts with acetone reversibly to generate the Ru isopropoxide, with the reaction free energy Delta G degrees(298 K) =-3.1 kcal/mol measured by H-1 NMR in tetrahydrofuran-d(8). Density functional theory (DFT), calibrated to the experimentally measured free energies of ketone insertion, was used to evaluate and compare the mechanism and energetics of insertion of acetone and CO2 into the Ru-hydride bond of 1. The calculated reaction coordinate for acetone insertion involves a stepwise outer-sphere dihydrogen transfer to acetone via hydride transfer from the metal and proton transfer from the N-H group on the CNN ligand. In contrast, the lowest energy pathway calculated for CO2 insertion proceeds by an initial Ru-H hydride transfer to CO2 followed by rotation of the resulting N-H-stabilized formate to a Ru-O-bound formate. DFT calculations were used to evaluate the influence of the ancillary ligands on the thermodynamics of CO2 insertion, revealing that increasing the pi acidity of the ligand cis to the hydride ligand and increasing the sigma basicity of the ligand trans to it decreases the free energy of CO2 insertion, providing a strategy for the design of metal hydride systems capable of reversible, ergoneutral interconversion of CO2 and formate.

Authors

I am an author on this paper
Click your name to claim this paper and add it to your profile.

Reviews

Primary Rating

4.7
Not enough ratings

Secondary Ratings

Novelty
-
Significance
-
Scientific rigor
-
Rate this paper

Recommended

No Data Available
No Data Available