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

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...

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Autores: Esteruelas, Miguel A., López, Ana M., Oñate, Enrique, Raga, Esther
Tipo de recurso: artículo
Estado:Versión aceptada para publicación
Fecha de publicación:2024
País:España
Institución:Universidad de Zaragoza
Repositorio:Zaguán. Repositorio Digital de la Universidad de Zaragoza
OAI Identifier:oai:zaguan.unizar.es:135485
Acceso en línea:http://zaguan.unizar.es/record/135485
Access Level:acceso abierto
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spelling Dehydrogenation of Formic Acid Catalyzed by an Osmium-Polyhydride: relevance of Acid Assistance in the CO2 Formation StageEsteruelas, Miguel A.López, Ana M.Oñate, EnriqueRaga, EstherComplex 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.2024info:eu-repo/semantics/articleinfo:eu-repo/semantics/acceptedVersionapplication/pdfhttp://zaguan.unizar.es/record/135485reponame:Zaguán. Repositorio Digital de la Universidad de Zaragozainstname:Universidad de ZaragozaInglésinfo:eu-repo/grantAgreement/ES/DGA/E06-23Rinfo:eu-repo/grantAgreement/ES/MICINN/PID2020-115286GB-I00info:eu-repo/grantAgreement/ES/MICINN/PRE2018-085398info:eu-repo/grantAgreement/ES/MICINN/RED2022-134287-Tinfo:eu-repo/semantics/openAccessoai:zaguan.unizar.es:1354852026-05-29T13:59:51Z
dc.title.none.fl_str_mv Dehydrogenation of Formic Acid Catalyzed by an Osmium-Polyhydride: relevance of Acid Assistance in the CO2 Formation Stage
title Dehydrogenation of Formic Acid Catalyzed by an Osmium-Polyhydride: relevance of Acid Assistance in the CO2 Formation Stage
spellingShingle Dehydrogenation of Formic Acid Catalyzed by an Osmium-Polyhydride: relevance of Acid Assistance in the CO2 Formation Stage
Esteruelas, Miguel A.
title_short Dehydrogenation of Formic Acid Catalyzed by an Osmium-Polyhydride: relevance of Acid Assistance in the CO2 Formation Stage
title_full Dehydrogenation of Formic Acid Catalyzed by an Osmium-Polyhydride: relevance of Acid Assistance in the CO2 Formation Stage
title_fullStr Dehydrogenation of Formic Acid Catalyzed by an Osmium-Polyhydride: relevance of Acid Assistance in the CO2 Formation Stage
title_full_unstemmed Dehydrogenation of Formic Acid Catalyzed by an Osmium-Polyhydride: relevance of Acid Assistance in the CO2 Formation Stage
title_sort Dehydrogenation of Formic Acid Catalyzed by an Osmium-Polyhydride: relevance of Acid Assistance in the CO2 Formation Stage
dc.creator.none.fl_str_mv Esteruelas, Miguel A.
López, Ana M.
Oñate, Enrique
Raga, Esther
author Esteruelas, Miguel A.
author_facet Esteruelas, Miguel A.
López, Ana M.
Oñate, Enrique
Raga, Esther
author_role author
author2 López, Ana M.
Oñate, Enrique
Raga, Esther
author2_role author
author
author
description 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.
publishDate 2024
dc.date.none.fl_str_mv 2024
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dc.identifier.none.fl_str_mv http://zaguan.unizar.es/record/135485
url http://zaguan.unizar.es/record/135485
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv info:eu-repo/grantAgreement/ES/DGA/E06-23R
info:eu-repo/grantAgreement/ES/MICINN/PID2020-115286GB-I00
info:eu-repo/grantAgreement/ES/MICINN/PRE2018-085398
info:eu-repo/grantAgreement/ES/MICINN/RED2022-134287-T
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
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