Rh Complexes with Pincer Carbene CNC Lutidine-Based Ligands: Reactivity Studies toward H2 Addition

Lutidine-based NHCs pincer precursors CNCMe and CNCMes were combined with [Rh(acac)(nbd)] (acac = acetylacetonate; nbd = 2, 5-norbornadiene) in the presence of Cs2CO3 to yield complexes [(CNC)MeRh(nbd)]PF6 (3) and [(CNC)MesRh(NCMe)]PF6 (4), respectively. While in 3, the nbd diolefin remains coordina...

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Autores: Hermosilla P., García-Orduña P., Lahoz F.J., Polo V., Casado M.A.
Formato: artículo
Estado:Versión aceptada para publicación
Fecha de publicación:2021
País:España
Recursos:Universidad de Zaragoza
Repositorio:Zaguán. Repositorio Digital de la Universidad de Zaragoza
OAI Identifier:oai:zaguan.unizar.es:165848
Acesso em linha:http://zaguan.unizar.es/record/165848
Access Level:acceso abierto
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spelling Rh Complexes with Pincer Carbene CNC Lutidine-Based Ligands: Reactivity Studies toward H2 AdditionHermosilla P.García-Orduña P.Lahoz F.J.Polo V.Casado M.A.Lutidine-based NHCs pincer precursors CNCMe and CNCMes were combined with [Rh(acac)(nbd)] (acac = acetylacetonate; nbd = 2, 5-norbornadiene) in the presence of Cs2CO3 to yield complexes [(CNC)MeRh(nbd)]PF6 (3) and [(CNC)MesRh(NCMe)]PF6 (4), respectively. While in 3, the nbd diolefin remains coordinated, in 4, the voluminous mesityl ligands induce nbd decoordination, so acetonitrile stabilizes Rh(I) adduct 4, which in turn undergoes substitution reactions with a number of neutral ligands to produce cationic complexes [(CNC)MesRh(L)]PF6 (L = CO (5), PMe2Ph (6), PEt3 (7), C2H4 (8)). These complexes have been studied through VT NMR measurements and the molecular structures by X-ray crystallography in the case of adducts 4-7. Deprotonation reactions on cationic complexes 3-6 with hard bases yielded the corresponding neutral complexes [(CNC)*MeRh(nbd)] (9) and mesityl derivatives [(CNC)*MesRh(L)] (L = NCCH3 (10), CO (11), PMe2Ph (12)), all of which are dearomatized complexes due to the deprotonation of one of the methylene arms, a situation confirmed by the X-ray molecular structure of carbonyl adduct 5. We studied the reactivity toward dihydrogen with neutral adducts 11 and 12. The electron rich phosphane 12 adds H2 through oxidative addition, affording the bis(hydrido) Rh(III) complex [(CNC)*MesRh(PMe2Ph)H2] (14). However, the carbonyl adduct 11 reacts with H2 in a different way, so that the central pyridinic ring becomes hydrogenated, breaking the aromaticity and leading to complex [(CNC-H2)*MesRh(CO)] (13), isolated as a mixture of two isomers. DFT studies were carried out in order to establish the mechanisms followed on these hydrogenations, finding that, while the phosphane adduct reacts following an oxidative addition mechanism, the carbonyl complex follows a more complex base-induced profile due to the instability of hydride carbonyl species. © 2021 American Chemical Society.2021info:eu-repo/semantics/articleinfo:eu-repo/semantics/acceptedVersionapplication/pdfhttp://zaguan.unizar.es/record/165848reponame:Zaguán. Repositorio Digital de la Universidad de Zaragozainstname:Universidad de ZaragozaInglésinfo:eu-repo/grantAgreement/ES/DGA-FSE/E42-20Rinfo:eu-repo/grantAgreement/ES/MINECO-FEDER/PGC2018-099383-B-I00info:eu-repo/semantics/openAccessoai:zaguan.unizar.es:1658482026-05-29T13:59:51Z
dc.title.none.fl_str_mv Rh Complexes with Pincer Carbene CNC Lutidine-Based Ligands: Reactivity Studies toward H2 Addition
title Rh Complexes with Pincer Carbene CNC Lutidine-Based Ligands: Reactivity Studies toward H2 Addition
spellingShingle Rh Complexes with Pincer Carbene CNC Lutidine-Based Ligands: Reactivity Studies toward H2 Addition
Hermosilla P.
title_short Rh Complexes with Pincer Carbene CNC Lutidine-Based Ligands: Reactivity Studies toward H2 Addition
title_full Rh Complexes with Pincer Carbene CNC Lutidine-Based Ligands: Reactivity Studies toward H2 Addition
title_fullStr Rh Complexes with Pincer Carbene CNC Lutidine-Based Ligands: Reactivity Studies toward H2 Addition
title_full_unstemmed Rh Complexes with Pincer Carbene CNC Lutidine-Based Ligands: Reactivity Studies toward H2 Addition
title_sort Rh Complexes with Pincer Carbene CNC Lutidine-Based Ligands: Reactivity Studies toward H2 Addition
dc.creator.none.fl_str_mv Hermosilla P.
García-Orduña P.
Lahoz F.J.
Polo V.
Casado M.A.
author Hermosilla P.
author_facet Hermosilla P.
García-Orduña P.
Lahoz F.J.
Polo V.
Casado M.A.
author_role author
author2 García-Orduña P.
Lahoz F.J.
Polo V.
Casado M.A.
author2_role author
author
author
author
description Lutidine-based NHCs pincer precursors CNCMe and CNCMes were combined with [Rh(acac)(nbd)] (acac = acetylacetonate; nbd = 2, 5-norbornadiene) in the presence of Cs2CO3 to yield complexes [(CNC)MeRh(nbd)]PF6 (3) and [(CNC)MesRh(NCMe)]PF6 (4), respectively. While in 3, the nbd diolefin remains coordinated, in 4, the voluminous mesityl ligands induce nbd decoordination, so acetonitrile stabilizes Rh(I) adduct 4, which in turn undergoes substitution reactions with a number of neutral ligands to produce cationic complexes [(CNC)MesRh(L)]PF6 (L = CO (5), PMe2Ph (6), PEt3 (7), C2H4 (8)). These complexes have been studied through VT NMR measurements and the molecular structures by X-ray crystallography in the case of adducts 4-7. Deprotonation reactions on cationic complexes 3-6 with hard bases yielded the corresponding neutral complexes [(CNC)*MeRh(nbd)] (9) and mesityl derivatives [(CNC)*MesRh(L)] (L = NCCH3 (10), CO (11), PMe2Ph (12)), all of which are dearomatized complexes due to the deprotonation of one of the methylene arms, a situation confirmed by the X-ray molecular structure of carbonyl adduct 5. We studied the reactivity toward dihydrogen with neutral adducts 11 and 12. The electron rich phosphane 12 adds H2 through oxidative addition, affording the bis(hydrido) Rh(III) complex [(CNC)*MesRh(PMe2Ph)H2] (14). However, the carbonyl adduct 11 reacts with H2 in a different way, so that the central pyridinic ring becomes hydrogenated, breaking the aromaticity and leading to complex [(CNC-H2)*MesRh(CO)] (13), isolated as a mixture of two isomers. DFT studies were carried out in order to establish the mechanisms followed on these hydrogenations, finding that, while the phosphane adduct reacts following an oxidative addition mechanism, the carbonyl complex follows a more complex base-induced profile due to the instability of hydride carbonyl species. © 2021 American Chemical Society.
publishDate 2021
dc.date.none.fl_str_mv 2021
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dc.identifier.none.fl_str_mv http://zaguan.unizar.es/record/165848
url http://zaguan.unizar.es/record/165848
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv info:eu-repo/grantAgreement/ES/DGA-FSE/E42-20R
info:eu-repo/grantAgreement/ES/MINECO-FEDER/PGC2018-099383-B-I00
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
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dc.source.none.fl_str_mv reponame:Zaguán. Repositorio Digital de la Universidad de Zaragoza
instname:Universidad de Zaragoza
instname_str Universidad de Zaragoza
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