130336 20240319081020.0 doi 10.1039/d1dt04335h sideral 131500 ART-2022-131500 eng Guzmán, Jefferson (orcid)0000-0001-9340-5952 Dehydrogenation of formic acid using iridium-NSi species as catalyst precursors 2022 Access copy available to the general public Unrestricted Using a low loading of the iridium(III) complexes [Ir(CF3SO3)(κ2-NSiiPr)2] (1) (NSiiPr = (4-methylpyridin-2-yloxy)diisopropylsilyl) and [{Ir(κ2-NSiMe)2}2(μ-CF3SO3)2] (2) (NSiMe = (4-methylpyridin-2-yloxy)dimethylsilyl) in the presence of Et3N, it has been possible to achieve the solventless selective dehydrogenation of formic acid. The best catalytic performance (TOF5 min ≈ 2900 h−1) has been achieved with 2 (0.1 mol%) and Et3N (40 mol% to FA) at 373 K. Kinetic studies at variable temperatures show that the activation energy of the 2-catalyzed process at 353 K is 22.8 ± 0.8 kcal mol−1. KIE values of 1.33, 2.86, and 3.33 were obtained for the 2-catalyzed dehydrogenation of HCOOD, DCOOH, and DCOOD, respectively, in the presence of 10 mol% of Et3N at 353 K. These data show that the activation of the C–H bond of FA is the rate-determining step of the process. A DFT mechanistic study for the catalytic cycle involving hydride abstraction from the formate anion by the metal, assisted by a molecule of formic acid, and heterolytic H2 formation has been performed. Moreover, the presence of Ir-formate intermediates was identified by means of NMR studies of the catalytic reactions in thf-d8 at 323 K. In all the cases, the decomposition of the catalyst to give unactive crystalline iridium NPs was observed. info:eu-repo/grantAgreement/ES/DGA-FSE/E42-20R info:eu-repo/grantAgreement/ES/MCIU/PGC2018-099383-B-I00 info:eu-repo/grantAgreement/ES/MICINN/RTI2018-099136-A-I00 info:eu-repo/semantics/openAccess All rights reserved http://www.europeana.eu/rights/rr-f/ 4.0 2022 CHEMISTRY, INORGANIC & NUCLEAR 7 / 42 = 0.167 2022 Q1 T1 0.79 2022 Inorganic Chemistry 2022 Q1 7.1 2022 info:eu-repo/semantics/article info:eu-repo/semantics/acceptedVersion Urriolabeitia, Asier Universidad de Zaragoza (orcid)0000-0001-9352-6922 Polo, Víctor Universidad de Zaragoza (orcid)0000-0001-5823-7965 Fernández-Buenestado, Marta Iglesias, Manuel (orcid)0000-0003-3144-5320 Fernández-Álvarez, Francisco J. Universidad de Zaragoza (orcid)0000-0002-0497-1969 2010 760 Universidad de Zaragoza Dpto. Química Inorgánica Área Química Inorgánica 2012 755 Universidad de Zaragoza Dpto. Química Física Área Química Física 51, 11 (2022), 4386-4393 Dalton Trans. Dalton Transactions 1477-9226 467821 http://zaguan.unizar.es/record/130336/files/texto_completo.pdf Postprint 2428994 http://zaguan.unizar.es/record/130336/files/texto_completo.jpg?subformat=icon icon Postprint oai:zaguan.unizar.es:130336 articulos driver 2024-03-18-16:03:17 ARTICLE