135485 20260217205533.0 doi 10.1021/acs.organomet.4c00064 sideral 138640 ART-2024-138640 eng Esteruelas, Miguel A. (orcid)0000-0002-4829-7590 Dehydrogenation of Formic Acid Catalyzed by an Osmium-Polyhydride: relevance of Acid Assistance in the CO2 Formation Stage 2024 Access copy available to the general public Unrestricted Complex OsH4{κ1-P,η2-GeH-[iPr2PCH(Me)CH2GeEt2H]}(PiPr3) (1) breaks down formic acid into H2 and CO2. The decomposition is catalytic with complex 1 being the main metallic species detected spectroscopically during the process. The kinetic analysis of the catalysis reveals that the decomposition rate is first order in the catalyst and independent of the concentration of formic acid, with the calculated activation parameters being: ΔH⧧ = 23 ± 2 kcal mol–1, ΔS⧧ = −1 ± 5 cal mol–1 K–1, and 298ΔG⧧ = 23 ± 3 kcal mol–1. Complex 1 also shows stoichiometric reactivity with benzoic and acetic acids. The reactions lead to OsH2{κ2-O,O-[O2CR]}{κ2-P,Ge-[iPr2PCH(Me)CH2GeEt2]}(PiPr3) (R = Ph (9), Me (10)). On the basis of these findings and DFT calculations, the following mechanism for the decomposition is proposed: complex 1 releases one molecule of H2 to produce an osmium(IV)-trihydride unsaturated intermediate, which promotes heterolytic activation of the O–H bond of formic acid. The metal fragment of the resulting osmium(IV)-(κ1-O-formate)-saturated derivative slides along the formate group, following the O–C–H pathway. The displacement is assisted externally by a molecule of formic acid and generates an osmium(IV)-(κ1-H-formate) species, which releases CO2 to regenerate 1 and close a cycle. The dissociation of H2 from the latter is the rate-determining step of catalysis. info:eu-repo/grantAgreement/ES/DGA/E06-23R info:eu-repo/grantAgreement/ES/MICINN/PID2020-115286GB-I00/AEI/10.13039/501100011033 info:eu-repo/grantAgreement/ES/MICINN/PRE2018-085398 info:eu-repo/grantAgreement/ES/MICINN/RED2022-134287-T info:eu-repo/semantics/openAccess All rights reserved http://www.europeana.eu/rights/rr-f/ 2.9 2024 CHEMISTRY, ORGANIC 14 / 57 = 0.246 2024 Q1 T1 CHEMISTRY, INORGANIC & NUCLEAR 17 / 43 = 0.395 2024 Q2 T2 0.676 2024 Inorganic Chemistry 2024 Q2 Physical and Theoretical Chemistry 2024 Q2 Organic Chemistry 2024 Q2 5.1 2024 info:eu-repo/semantics/article info:eu-repo/semantics/acceptedVersion López, Ana M. Universidad de Zaragoza (orcid)0000-0001-7183-4975 Oñate, Enrique (orcid)0000-0003-2094-719X Raga, Esther (orcid)0000-0001-8609-7947 2010 760 Universidad de Zaragoza Dpto. Química Inorgánica Área Química Inorgánica 43, 10 (2024), 1110–1118 Organometallics Organometallics 0276-7333 584082 http://zaguan.unizar.es/record/135485/files/texto_completo.pdf Postprint 1137269 http://zaguan.unizar.es/record/135485/files/texto_completo.jpg?subformat=icon icon Postprint oai:zaguan.unizar.es:135485 articulos driver 2026-02-17-20:33:18 ARTICLE