Dehydrogenation of Formic Acid Catalyzed by an Osmium-Polyhydride: relevance of Acid Assistance in the CO2 Formation Stage

Esteruelas, Miguel A. ; López, Ana M. (Universidad de Zaragoza) ; Oñate, Enrique ; Raga, Esther

Resumen: 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.

Idioma: Inglés

DOI: 10.1021/acs.organomet.4c00064

Año: 2024

Publicado en: Organometallics 43, 10 (2024), 1110–1118
ISSN: 0276-7333

Factor impacto JCR: 2.9 (2024)

Categ. JCR: CHEMISTRY, ORGANIC rank: 14 / 57 = 0.246 (2024) - Q1 - T1
Categ. JCR: CHEMISTRY, INORGANIC & NUCLEAR rank: 17 / 43 = 0.395 (2024) - Q2 - T2

Factor impacto CITESCORE: 5.1 - Physical and Theoretical Chemistry (Q2) - Organic Chemistry (Q2) - Inorganic Chemistry (Q2)

Factor impacto SCIMAGO: 0.676 - Inorganic Chemistry (Q2) - Physical and Theoretical Chemistry (Q2) - Organic Chemistry (Q2)

Financiación: info:eu-repo/grantAgreement/ES/DGA/E06-23R
Financiación: info:eu-repo/grantAgreement/ES/MICINN/PID2020-115286GB-I00/AEI/10.13039/501100011033
Financiación: info:eu-repo/grantAgreement/ES/MICINN/PRE2018-085398
Financiación: info:eu-repo/grantAgreement/ES/MICINN/RED2022-134287-T

Tipo y forma: Article (PostPrint)

Área (Departamento): Área Química Inorgánica (Dpto. Química Inorgánica)