01386nas a2200241   4500008004100000022001400041245008900055210006900144260009500213300001200308490000800320520046100328653002500789653003600814653002800850653003000878100001700908700001800925700003000943700001900973700002600992856012601018       2005                        eng d  a0021-951700aMCM-41-supported platinum carbonyl cluster-derived asymmetric hydrogenation catalyst0 aMCM41supported platinum carbonyl clusterderived asymmetric hydro  a525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USAbACADEMIC PRESS INC ELSEVIER SCIENCEcJAN  a298-3020 v2293 a<p>Anionic platinum carbonyl cluster has been ion paired with cinchonidium groups that are chemically bound to the surface of MCM-41 and fumed silica. In the hydrogenation of methyl pyruvate or acetophenone the fumed silica-based catalyst gives zero enantioselectivity, but under optimum conditions enantiomeric excesses of &gt;90 and similar to40%, respectively, are obtained with the MCM-41-based catalyst. (C) 2004 Elsevier Inc. All rights reserved.</p>10aasymmetric catalysis10afunctionalized inorganic oxides10ahydrogenation catalysts10aplatinum carbonyl cluster1 aBasu, Susmit1 aPaul, Himadri1 aGopinath, Chinnakonda, S.1 aBhaduri, Sumit1 aLahiri, Goutam, Kumar  uhttps://library.ncl.res.in/content/mcm-41-supported-platinum-carbonyl-cluster-derived-asymmetric-hydrogenation-catalyst-002690nas a2200313   4500008004100000022001400041245011600055210006900171260009500240300001200335490000800347520155000355653003601905653002801941653001101969653003001980653002002010653001802030653000802048100001902056700001702075700001702092700003502109700002702144700003002171700001902201700002602220856013002246       2006                        eng d  a0021-951700aEffect of spacer groups on the performance of MCM-41-supported platinum cluster-derived hydrogenation catalysts0 aEffect of spacer groups on the performance of MCM41supported pla  a525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USAbACADEMIC PRESS INC ELSEVIER SCIENCEcSEP  a332-3390 v2423 a<p>MCM-41 was functionalized with (EtO)(3)SiCH2Cl, (MeO)(3)SiCH2CH2CH2Cl, and (CH3)Cl2SiCH2Cl. The functionalized materials were characterized by solid-state NMR (CPMAS, Si-29 and C-13) and XPS. The NMR data indicate that three new silicon environments were created by(EtO)(3)SiCH2Cl and (MeO)(3)SiCH2CH2CH2Cl, whereas with (CH3)Cl2SiCH2Cl, two new silicon environments were obtained. XPS results from Si 2p core level and the valence band from the material functionalized by (MeO)(3)Si(CH2)(3)Cl was found to be the same as that of the corresponding fresh catalyst (1a), in contrast to that of the materials functionalized by the other two silane reagents. After further functionalization with triethylamine, these materials were used as inorganic anion exchangers to support the cluster anion [Pt-12(CO)(24)](2-). Solid-state NMR (29Si, C-13, N-15) was used to establish the presence of the quaternary ammonium group in the cluster-supported species. Analogous materials were also created using fumed silica as the support, and all of the cluster-supported materials were tested as catalysts for the hydrogenation of methyl pyruvate, acetophenone, nitrobenzene, benzonitrile, ethylacetoacetate, 4-nitrotoluene, cyclohexanone, allyl alcohol, and styrene. The best activity was obtained for the catalyst that had MCM-41 as the support and chloropropyl as the spacer group. TEM showed that the supports and the spacer groups had observable effects on the platinum crystallite size of the catalysts. (c) 2006 Elsevier Inc. All rights reserved.</p>10afunctionalized inorganic oxides10ahydrogenation catalysts10aMCM-4110aplatinum carbonyl cluster10aSolid-state NMR10aspacer groups10aXPS1 aMaity, Niladri1 aBasu, Susmit1 aMapa, Maitri1 aRajamohanan, Pattuparambil, R.1 aGanapathy, Subramanian1 aGopinath, Chinnakonda, S.1 aBhaduri, Sumit1 aLahiri, Goutam, Kumar  uhttps://library.ncl.res.in/content/effect-spacer-groups-performance-mcm-41-supported-platinum-cluster-derived-hydrogenation-102188nas 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