000127873 001__ 127873
000127873 005__ 20231023120953.0
000127873 0247_ $$2doi$$a10.1021/om5013083
000127873 0248_ $$2sideral$$a89691
000127873 037__ $$aART-2015-89691
000127873 041__ $$aeng
000127873 100__ $$0(orcid)0000-0002-0545-9107$$aJiménez,M. V.$$uUniversidad de Zaragoza
000127873 245__ $$aMechanistic insights into transfer hydrogenation catalysis by [Ir(cod)(NHC)2]+ complexes with functionalized N-heterocyclic carbene ligands
000127873 260__ $$c2015
000127873 5060_ $$aAccess copy available to the general public$$fUnrestricted
000127873 5203_ $$aThe synthesis of unbridged biscarbene iridium(I) [Ir(cod)(MeIm∩Z)2]+ complexes having N- or O-functionalized NHC ligands (∩Z = 2-methoxybenzyl, pyridin-2-ylmethyl, quinolin-8-ylmethyl) is described. The molecular structures of the complexes show an antiparallel disposition of the carbene ligands that minimize the steric repulsions between the bulky substituents. However, the complexes were found to be dynamic in solution, due to the restricted rotation about the C(carbene)–Ir bond that results in two interconverting diasteromers having different dispositions of the functionalized NHC ligands. A rotational barrier of around 80 kJ mol–1 (298 K) has been determined by 2D EXSY NMR spectroscopy. The iridium(III) dihydride complex [IrH2(MeIm∩Z)2]+ (∩Z = pyridin-2-ylmethyl) has been prepared by reaction of the corresponding iridium(I) complex with molecular hydrogen. These complexes efficiently catalyzed the transfer hydrogenation of cyclohexanone using 2-propanol as a hydrogen source and KOH as base at 80 °C with average TOF values of 117–155 h–1 at 0.1 mol % iridium catalyst loading. All of the catalyst precursors showed comparable activity independent of both the wingtip type at the NHC ligands and the counterion. Mechanistic studies support the involvement of diene free bis-NHC iridium(I) intermediates in these catalytic systems. DFT calculations have shown that a MPV-like concerted mechanism (Meerwein–Ponndorf–Verley mechanism), involving the direct hydrogen transfer at the coordination sphere of the iridium center, might compete with the well-established hydrido mechanism. Indirect evidence of a MPV-like mechanism has been found for the catalyst precursor having NHC ligands having with a pyridin-2-ylmethyl wingtip.
000127873 536__ $$9info:eu-repo/grantAgreement/ES/DGA/E07$$9info:eu-repo/grantAgreement/ES/MICINN/CSD2009-00050$$9info:eu-repo/grantAgreement/ES/MINECO-FEDER/CTQ2013-42532-P
000127873 540__ $$9info:eu-repo/semantics/openAccess$$aAll rights reserved$$uhttp://www.europeana.eu/rights/rr-f/
000127873 590__ $$a4.186$$b2015
000127873 591__ $$aCHEMISTRY, ORGANIC$$b12 / 59 = 0.203$$c2015$$dQ1$$eT1
000127873 591__ $$aCHEMISTRY, INORGANIC & NUCLEAR$$b9 / 46 = 0.196$$c2015$$dQ1$$eT1
000127873 592__ $$a1.923$$b2015
000127873 593__ $$aInorganic Chemistry$$c2015$$dQ1
000127873 593__ $$aPhysical and Theoretical Chemistry$$c2015$$dQ1
000127873 593__ $$aOrganic Chemistry$$c2015$$dQ1
000127873 655_4 $$ainfo:eu-repo/semantics/article$$vinfo:eu-repo/semantics/acceptedVersion
000127873 700__ $$aFernández-Tornos,J.
000127873 700__ $$0(orcid)0000-0002-3327-0918$$aPérez-Torrente,J. J.$$uUniversidad de Zaragoza
000127873 700__ $$0(orcid)0000-0002-9633-3285$$aModrego,F. J.$$uUniversidad de Zaragoza
000127873 700__ $$0(orcid)0000-0002-7063-1292$$aGarcía-Orduña,P.$$uUniversidad de Zaragoza
000127873 700__ $$0(orcid)0000-0001-7154-7239$$aOro,L. A.$$uUniversidad de Zaragoza
000127873 7102_ $$12010$$2760$$aUniversidad de Zaragoza$$bDpto. Química Inorgánica$$cÁrea Química Inorgánica
000127873 773__ $$g34, 5 (2015), 926-940$$pOrganometallics$$tOrganometallics$$x0276-7333
000127873 8564_ $$s1426299$$uhttps://zaguan.unizar.es/record/127873/files/texto_completo.pdf$$yPostprint
000127873 8564_ $$s669937$$uhttps://zaguan.unizar.es/record/127873/files/texto_completo.jpg?subformat=icon$$xicon$$yPostprint
000127873 909CO $$ooai:zaguan.unizar.es:127873$$particulos$$pdriver
000127873 951__ $$a2023-10-23-11:02:37
000127873 980__ $$aARTICLE