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Catalytic Hydrogenation Activity and Electronic Structure Determination of Bis(arylimidazol-2-ylidene)pyridine Cobalt Alkyl and Hydride Complexes

Author(s): Yu, Renyuan Pony; Darmon, Jonathan M; Milsmann, Carsten; Margulieux, Grant W; Stieber, S Chantal E; et al

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dc.contributor.authorYu, Renyuan Pony-
dc.contributor.authorDarmon, Jonathan M-
dc.contributor.authorMilsmann, Carsten-
dc.contributor.authorMargulieux, Grant W-
dc.contributor.authorStieber, S Chantal E-
dc.contributor.authorDeBeer, Serena-
dc.contributor.authorChirik, Paul J-
dc.date.accessioned2017-04-04T20:17:59Z-
dc.date.available2017-04-04T20:17:59Z-
dc.date.issued2013-09-04en_US
dc.identifier.citationYu, Renyuan Pony, Darmon, Jonathan M, Milsmann, Carsten, Margulieux, Grant W, Stieber, S Chantal E, DeBeer, Serena, Chirik, Paul J. (2013). Catalytic Hydrogenation Activity and Electronic Structure Determination of Bis(arylimidazol-2-ylidene)pyridine Cobalt Alkyl and Hydride Complexes. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 135 (13168 - 13184. doi:10.1021/ja405608uen_US
dc.identifier.issn0002-7863-
dc.identifier.urihttp://arks.princeton.edu/ark:/88435/pr1p89c-
dc.description.abstractThe bis(arylimidazol-2-ylidene)pyridine cobalt methyl complex, ((CNC)-C-iPr)CoCH3, was evaluated for the catalytic hydrogenation of alkenes. At 22 degrees C and 4 atm of H-2 pressure, ((CNC)-C-iPr)CoCH3 is an effective precatalyst for the hydrogenation of sterically hindered, unactivated alkenes such as trans-methylstilbene, 1-methyl-1-cyclohexene, and 2,3-dimethyl-2-butene, representing one of the most active cobalt hydrogenation catalysts reported to date. Preparation of the cobalt hydride complex, ((CNC)-C-iPr)CoH, was accomplished by hydrogenation of ((CNC)-C-iPr)CoCH3. Over the course of 3 h at 22 degrees C, migration of the metal hydride to the 4-position of the pyridine ring yielded (4-H-2-(CNC)-C-iPr)CoN2. Similar alkyl migration was observed upon treatment of ((CNC)-C-iPr)CoH with 1,1-diphenylethylene. This reactivity raised the question as to whether this class of chelate is redox-active, engaging in radical chemistry with the cobalt center. A combination of structural, spectroscopic, and computational studies was conducted and provided definitive evidence for bis(arylimidazol-2-ylidene)pyridine radicals in reduced cobalt chemistry. Spin density calculations established that the radicals were localized on the pyridine ring, accounting for the observed reactivity, and suggest that a wide family of pyridine-based pincers may also be redox-active.en_US
dc.format.extent13168 - 13184en_US
dc.language.isoen_USen_US
dc.relation.ispartofJOURNAL OF THE AMERICAN CHEMICAL SOCIETYen_US
dc.rightsAuthor's manuscripten_US
dc.titleCatalytic Hydrogenation Activity and Electronic Structure Determination of Bis(arylimidazol-2-ylidene)pyridine Cobalt Alkyl and Hydride Complexesen_US
dc.typeJournal Articleen_US
dc.identifier.doidoi:10.1021/ja405608u-
pu.type.symplectichttp://www.symplectic.co.uk/publications/atom-terms/1.0/journal-articleen_US

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