title: Single-Site Osmium Catalysts on MgO: Reactivity and Catalysis of CO Oxidation.
abstract: MgO-supported osmium dioxo species, described as Os(=O)2{-Osupport}1 or 2(the brackets denote O atoms of the MgO surface), formed from Os3(CO)12via supported Os(CO)2, and characterized by spectroscopy, microscopy, and theory, react with ethylene at 298 K to form osmium glycol species or with CO to give osmium mono- and di-carbonyls. Os(=O)2{-Osupport}1 or 2is the precursor of a CO oxidation catalyst characterized by a turnover frequency of 4.0×10-3(molecules of CO)/(Os atom×s) at 473 K; the active species are inferred to be osmium monocarbonyls. The structures and frequencies calculated at the level of density functional theory with the B3LYP functional bolster the experimental results and facilitate structural assignments. The lowest-energy structures have various osmium oxidation and spin states. The results demonstrate not only new chemistry of the supported single-site catalysts but also their complexity and the value of complementary techniques used in concert to unravel the chemistry.
authors.affiliation: Department of Chemical Engineering and (formerly) Materials Science, University of California, Davis, California, 95616, USA.
authors.forename: Dong
authors.identifier: http://orcid.org/0000-0003-4199-7065
authors.initials: D
authors.lastname: Yang
authors.affiliation: Department of Chemistry, The University of Alabama, Shelby Hall, Box 87036, Tuscaloosa, AL, 35487-0336, USA.
authors.forename: Shengjie
authors.identifier: http://orcid.org/0000-0003-4158-9010
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Chemical Engineering and (formerly) Materials Science, University of California, Davis, California, 95616, USA.
authors.forename: Pinghong
authors.initials: P
authors.lastname: Xu
authors.affiliation: Physical and Computational Sciences, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington, 99352, USA.
authors.forename: Nigel D
authors.identifier: http://orcid.org/0000-0003-0491-251X
authors.initials: ND
authors.lastname: Browning
authors.affiliation: Department of Chemistry, The University of Alabama, Shelby Hall, Box 87036, Tuscaloosa, AL, 35487-0336, USA.
authors.forename: David A
authors.identifier: http://orcid.org/0000-0002-4903-301X
authors.initials: DA
authors.lastname: Dixon
authors.affiliation: Department of Chemical Engineering and (formerly) Materials Science, University of California, Davis, California, 95616, USA.
authors.forename: Bruce C
authors.identifier: http://orcid.org/0000-0003-0274-4882
authors.initials: BC
authors.lastname: Gates
keywords: CO oxidation; carbonyl ligands; osmium; oxo ligands; supported catalysts