New Ru (II) complexes containing oxazoline ligands as epoxidation catalysts: influence of the substituents on the catalytic performance
dc.contributor.author
dc.date.accessioned
2015-12-15T11:14:14Z
dc.date.available
2015-12-15T11:14:14Z
dc.date.issued
2011-07-04
dc.identifier.issn
0020-1669
dc.identifier.uri
dc.description.abstract
The synthesis of a family of new Ru complexes containing the facial tridentate ligand with general formula [RuII(T)(D)(X)]n+ (T = trispyrazolylmethane (tpm); D = ((4S,4′S)-(-)-4,4′,5,5′- tetrahydro-4,4′-bis(1-methylethyl)-2,2′-bioxazole) (iPr-box-C) or N-(1-hydroxy-3-methylbutan-(2S)-(-)-2-yl)-(4S)-(-)-4-isopropyl-4, 5-dihydrooxazole-2-carbimidate (iPr-box-O); X = Cl, H2O) has been described. All complexes have been spectroscopically characterized in solution through 1H NMR and UV-vis techniques, and the redox properties of complexes have also been studied by means of cyclic voltammetry (CV). Furthermore, the chloro complexes presented here have been characterized in the solid state through monocrystal X-ray diffraction analysis. The oxazolinic iPr-box-C ligand undergoes a Ru-assisted hydrolysis reaction generating the corresponding amidate anionic ligand iPr-box-O, that keeps coordinated to the Ru metal center and that produces a strong σ-donation effect over it. The reactivity of the Ru-OH2 complexes described in this paper together with other similar ones, previously synthesized by us, has been tested with regard to the epoxidation of different olefins. Complexes [Ru II(R-box-C)(tpm)OH2](BF4)2, R = Bz, 3′c/iPr, 3c, show high stereoselectivity in the epoxidation of cis-β-methylstyrene, with the exclusive formation of the cis-epoxide. However, there is a significant difference in regioselectivity between the two catalysts in the epoxidation of 4-vinylcyclohexene; complex 3′c leads to the regioselective oxidation at the ring alkene position, whereas complex 3c leads to the oxidation at the terminal position. Computational calculations indicate only small energy differences between the two possible products of 4-vinylcyclohexene epoxidation, but the energy barriers for the interaction of the catalytic systems with the alkene groups of 4-vinylcyclohexene agree with the reactivity differences found for the two catalysts having isopropyl or benzyl as substituent of the oxazole ligand. Computed local Fukui functions help to explain the observed reactivity trends
dc.description.sponsorship
We acknowledge financial support from the MICINNof Spain (CTQ2010-21532-C02-01 to I.R. and M.R., CTQ2009-08328 to T.P., CTQ2010-21497 and Consolider Ingenio 2010 CSD2006-0003 to A.L. and CTQ2008-03077/BQU to M.S.) and the DIUE of Catalonia (2009SGR637). M.S. is also grateful to the DIUE of the Generalitat de Catalunya for financial help through the ICREA Academia 2009 prize for excellence in research. A.P. thanks MICINN for a Ram on y Cajal contract (ref RYC-2009-04170). Johnson & Matthey LTD are acknowledged for a RuCl3 3 nH2O loan. We also thank Centre de Supercomputaci o de Catalunya (CESCA) for partial funding of computer time
dc.format.mimetype
application/pdf
dc.language.iso
eng
dc.publisher
American Chemical Society (ACS)
dc.relation
info:eu-repo/grantAgreement/MICINN//CTQ2010-21532-C02-01/ES/MIMETIZACION DE PROCESOS BIOINORGANICOS Y APLICACIONES CATALITICAS CON COMPUESTOS DE METALES DE TRANSICION./
info:eu-repo/grantAgreement/MICINN//CTQ2008-03077/ES/CLUSTERES METALICOS Y SEMIMETALICOS. ESTUDIOS DE AROMATICIDAD Y REACTIVIDAD/
dc.relation.isformatof
Reproducció digital del document publicat a: http://dx.doi.org/10.1021/ic200053f
dc.relation.ispartof
© Inorganic Chemistry, 2011, vol. 50, núm. 13, p. 6044-6054
dc.relation.ispartofseries
Articles publicats (D-Q)
dc.rights
Tots els drets reservats
dc.title
New Ru (II) complexes containing oxazoline ligands as epoxidation catalysts: influence of the substituents on the catalytic performance
dc.type
info:eu-repo/semantics/article
dc.rights.accessRights
info:eu-repo/semantics/embargoedAccess
dc.embargo.terms
Cap
dc.date.embargoEndDate
info:eu-repo/date/embargoEnd/2026-01-01
dc.type.version
info:eu-repo/semantics/publishedVersion
dc.identifier.doi
dc.identifier.idgrec
015414
dc.contributor.funder
dc.relation.ProjectAcronym
dc.identifier.eissn
1520-510X