165028 20260115130450.0 doi 10.1021/acs.organomet.5c00356 sideral 146481 ART-2025-146481 eng Villanueva Alli, Iñigo Universidad de Zaragoza Polyhydride Osmium-Mediated Hydrosilylation of Carbonyl Compounds: Intermediates and Mechanism 2025 Access copy available to the general public Unrestricted OsH6(PiPr3)2 (1) reacts with phenylsilane to afford OsH5(SiH2Ph)(PiPr3)2 (2), which reacts with additional phenylsilane to give OsH4(SiH2Ph)2(PiPr3)2 (3). The reaction of 1 with diphenylsilane affords OsH5(SiHPh2)(PiPr3)2 (4), which in the presence of diphenylsilane and traces of water leads to OsH4{κ2-Si,Si-(Ph2Si–O–SiPh2)}(PiPr3)2 (5). Complex 4 promotes the hydrosilylation of aldehydes with H2SiPh2 to give silyl ethers, while for ketones mixtures of hydrosilylation and dehydrogenative silylation products are obtained. The reactions of 4 with benzaldehyde and acetone afford OsH5{Si(OR)Ph2}(PiPr3)2 (R = CH2Ph (6), iPr (7)), which undergo a metathesis between a Si–Ph bond and a C(sp3)–H bond of one methyl group of one phosphine to give OsH4{κ1-P,η2-SiH-[iPr2PCH(Me)CH2Si(OR)PhH]}(PiPr3) (R = CH2Ph (8), iPr (9)). The combination of experimental findings and density functional theory calculations has permitted to establish the mechanism for the hydrosilylation processes. The key intermediate is the tetrahydride-silylene OsH4(=SiPh2)(PiPr3)2, formed by an outer-sphere hydrogenation of the carbonyl group promoted by a trihydride(dihydrogen) isomer of 4. For enolyzable ketones, this pathway competes with one where the enol form directly attacks the Si atom of 4, affording silyl enol ethers and a tetrahydride(dihydrogen) isomer of 1, that reacts with diphenylsilane to release hydrogen and close the cycle. info:eu-repo/grantAgreement/ES/AEI/PID2023-146967NB-I00 info:eu-repo/grantAgreement/ES/DGA/E06-23R info:eu-repo/semantics/embargoedAccess All rights reserved http://www.europeana.eu/rights/rr-f/ info:eu-repo/semantics/article info:eu-repo/semantics/acceptedVersion Oñate, Enrique (orcid)0000-0003-2094-719X Oliván, Montserrat (orcid)0000-0003-0381-0917 2010 760 Universidad de Zaragoza Dpto. Química Inorgánica Área Química Inorgánica 44 (2025), 2749-2762 Organometallics Organometallics 0276-7333 1447313 http://zaguan.unizar.es/record/165028/files/texto_completo.pdf Postprint info:eu-repo/date/embargoEnd/2026-11-18 1120481 http://zaguan.unizar.es/record/165028/files/texto_completo.jpg?subformat=icon icon Postprint info:eu-repo/date/embargoEnd/2026-11-18 oai:zaguan.unizar.es:165028 articulos driver 2026-01-15-12:57:46 ARTICLE