N-heterocyclic carbene-based molybdenum and tungsten complexes as efficient epoxidation catalysts with H2O2 and tert-butyl hydroperoxide

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Abstract

The molybdenum and tungsten g eta(3)-allyl dicarbonyl complexes bearing N-heterocyclic carbene (NHC) ligands [M(eta(3)-C3H5)Cl(CO)(2)(bis-NHCBz)] (M = Mo, W; bis-NHCBz = 1,1'-dibenzyl-3,3'-methylenediimidazoline-2,2'-diylidene) have been prepared from the corresponding acetonitrile precursors [M(eta(3)-C3H5)Cl(CO)(2)(NCMe)(2)] by treatment with free carbene. Their catalytic performance in epoxidation of cis-cyclooctene using H2O2 as oxidant has been studied. All complexes can be applied as catalysts precursors in olefin epoxidation displaying 100% selectivity for the formation of cyclooctene oxide. The tungsten acetonitrile precursor [W(eta(3)-C3H5)Cl(CO)(2)(NCMe)(2)] displayed the highest catalytic activity achieving quantitative conversion of epoxide in 30 min. The molybdenum NHC-based compound [Mo(eta(3)-C3H5)Cl(CO)(2)(bis-NHCBz)] displayed higher activity when the epoxidation reaction was performed using H2O2 as oxidant compared to tert-butyl hydroperoxide
Original languageUnknown
Pages (from-to)222-227
JournalCatalysis Letters
Volume136
Issue number3-4
DOIs
Publication statusPublished - 1 Jan 2010

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