Alkene Epoxidation Catalysts [Ru(pdc)(tpy)] and [Ru(pdc)(pybox)] Revisited: Revealing a Unique Ru-IV=O Structure from a Dimethyl Sulfoxide Coordinating Complex
Number of Authors: 7
2015 (English)In: ACS Catalysis, ISSN 2155-5435, Vol. 5, no 7, 3966-3972 p.Article in journal (Refereed) Published
The X-ray crystal structure of a dimethyl sulfoxide (DMSO) coordinating complex [Ru-II(kappa(2)-pdc)(tpy)(DMSO)] (H(2)pdc = 2,6-pyridyl dicarboxylic acid and tpy = 2,2':6',2 ''-terpyridine) led to the discovery of a unique Ru-IV=O configuration for the Ru-pybox (pybox = pyridine-bis(oxazoline) ligands) epoxidation catalyst by theoretical calculations. On the basis of this structure, a detailed theoretical study was conducted on the alkene epoxidation reaction using ruthenium-based epoxidation catalysts. It was found that the process of H2O2 coordination proceeded via an associative path in which one carboxylate detached. The following H2O-elimination step was found to be facilitated by the detached carboxylate group. The resulting Ru-IV=O rearranges to the species trans-2a-oxo, in which one carboxylate group is situated over the tpy ring; the trans-2a-oxo was found to have the lowest activation free energies toward alkene epoxidation. These results demonstrated the importance of the hemilabile properties of the pdc(2-) ligand for the Ru-pdc alkene epoxidation catalysts.
Place, publisher, year, edition, pages
2015. Vol. 5, no 7, 3966-3972 p.
epoxidation, ruthenium, DFT, hemilabile, oxidation, mechanism
IdentifiersURN: urn:nbn:se:su:diva-119743DOI: 10.1021/acscatal.5b00496ISI: 000357626800008OAI: oai:DiVA.org:su-119743DiVA: diva2:849222