02188nas a2200265   4500008004100000022001400041245012200055210006900177260009500246300001200341490000800353520115600361653004001517653002301557653002601580653002801606653003001634100001701664700001701681700003001698700001801728700001901746700002601765856013101791       2006                        eng d  a0021-951700aMCM-41-supported platinum carbonyl cluster-derived catalysts for asymmetric and nonasymmetric hydrogenation reactions0 aMCM41supported platinum carbonyl clusterderived catalysts for as  a525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USAbACADEMIC PRESS INC ELSEVIER SCIENCEcAPR  a154-1610 v2393 a<p>Anionic platinum carbonyl Cluster ([Pt-12(CO)(24)](2-)) was ion-paired with the 3-chloropropyltrimethoxysilyl-ammonium group chemically bound to the surface of MCM-41. The materials undergo quick decarbonylation and have been characterized before decarbonylation by IR and UV-vis spectroscopy and after decarbonylation by XPS and TEM. They have been used as catalysts for the hydrogenations of methyl pyruvate, acetophenone, nitrobenzene, benzonitrile, and ethylacetoacetate. The support and the quaternary ammonium groups have significant effects on surface platinum concentration, crystallite size, and observed activity. In the hydrogenation of the prochiral substrates methyl pyruvate or acetophenone, the cinchonidine-based catalyst gives significant enantioselectivity under optimum conditions. A kinetic model that includes an enantioselective product-formation step and a hydrogen pressure-dependent step for the deactivation of the enantioselective sites gives reasonable agreement between predicted and observed enantioselectivity. The model is also in accordance with the XPS and TEM data. (c) 2006 Elsevier Inc. All rights reserved.</p>10aasymmetric/non-asymmetric catalysis10aEnantioselectivity10afunctionalized MCM-4110ahydrogenation catalysts10aplatinum carbonyl cluster1 aBasu, Susmit1 aMapa, Maitri1 aGopinath, Chinnakonda, S.1 aDoble, Mukesh1 aBhaduri, Sumit1 aLahiri, Goutam, Kumar  uhttps://library.ncl.res.in/content/mcm-41-supported-platinum-carbonyl-cluster-derived-catalysts-asymmetric-and-nonasymmetric-101233nas a2200265   4500008004100000022001400041245010500055210006900160260007300229300001200302490000800314520025000322653002500572653002600597653002800623653001700651653003100668100001900699700001700718700002900735700003000764700001900794700002600813856012800839       2008                        eng d  a0926-860X00aMCM-41-supported ruthenium carbonyl cluster-derived catalysts for asymmetric hydrogenation reactions0 aMCM41supported ruthenium carbonyl clusterderived catalysts for a  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcJUL  a124-1300 v3443 a<p>{The anionic ruthenium carbonyl cluster [Ru-4(mu-H)(3)(CO)(12)](-) has been ion-paired with (3-chloropropyl)-trimethoxysilyl-cinchonidium or sparteinium groups chemically bound to the surfaces of MCM-41 [(MCM-41-)(-O)(3)SiCH2CH2CH2NR3+Cl-</p>10aasymmetric catalysis10afunctionalized MCM-4110ahydrogenation catalysts10ananocatalyst10aruthenium carbonyl cluster1 aIndra, Arindam1 aBasu, Susmit1 aKulkarni, Dhanashree, G.1 aGopinath, Chinnakonda, S.1 aBhaduri, Sumit1 aLahiri, Goutam, Kumar  uhttps://library.ncl.res.in/content/mcm-41-supported-ruthenium-carbonyl-cluster-derived-catalysts-asymmetric-hydrogenation-0