Multiple Surface Site Three-Dimensional Structure Determination of a Supported Molecular Catalyst
| Autor: | Ribal Jabbour, Marc Renom-Carrasco, Ka Wing Chan, Laura Völker, Pierrick Berruyer, Zhuoran Wang, Cory M. Widdifield, Moreno Lelli, David Gajan, Christophe Copéret, Chloé Thieuleux, Anne Lesage |
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| Přispěvatelé: | Centre de RMN à très hauts champs de Lyon (CRMN), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Catalyse, Polymérisation, Procédés et Matériaux (CP2M), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École Supérieure de Chimie Physique Électronique de Lyon (CPE)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry and Applied Biosciences [ETH Zürich] (D-CHAB), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Ecole Polytechnique Fédérale de Lausanne (EPFL), University of Regina (UR), Magnetic Resonance Center (CERM), Università degli Studi di Firenze = University of Florence (UniFI), ANR-17-CE29-0006,SEQUANS,Spectroscopie RMN Quadripolaire de Surface Exaltée par DNP(2017) |
| Rok vydání: | 2022 |
| Předmět: |
Molecular Structure
spatial-distribution [CHIM.MATE]Chemical Sciences/Material chemistry [CHIM.CATA]Chemical Sciences/Catalysis General Chemistry chemistry Iridium Ligands Biochemistry Catalysis Colloid and Surface Chemistry Heterocyclic Compounds dynamic nuclear-polarization metal-catalysts screening model Organometallic Compounds solid-state nmr dnp solvation organic functional-groups approximation |
| Zdroj: | Journal of the American Chemical Society Journal of the American Chemical Society, 2022, 144 (23), pp.10270-10281. ⟨10.1021/jacs.2c01013⟩ |
| ISSN: | 1520-5126 0002-7863 |
| DOI: | 10.1021/jacs.2c01013 |
| Popis: | International audience; The structural characterization of supported molecular catalysts is challenging due to the low concentration of surface sites and the presence of several organic/organometallic surface groups resulting from the often complex surface chemistry associated with support functionalization. Here, we provide a complete atomic-scale description of all surface sites in a silica-supported iridium-N-heterocyclic carbene (Ir-NHC) catalytic material, at all stages of its synthesis. By combining a suitable isotope labelling strategy with the implementation of multi-nuclear dipolar recoupling DNP enhanced NMR experiments, the 3D structure of the Ir-NHC sites, as well as that of the synthesis intermediates were determined. As a significant fraction of parent surface fragments does not react during the multi-step synthesis, site-selective experiments were implemented to specifically probe proximities between the organometallic groups and the solid support. The NMR-derived structure of the iridium sites points to a well-defined conformation. By interpreting extended x-ray absorption fine structure (EXAFS) spectroscopy and chemical analysis data augmented by computational studies, the presence of two coordination geometries is demonstrated: Ir-NHC fragments coordinated by a 1,5-cyclooctadiene and one Cl ligand, as well as, more surprisingly, a fragment coordinated by two NHC and two Cl ligands. This study demonstrates a unique methodology to disclose individual surface structures in complex, multi-site environments, a long-standing challenge in the field of heterogeneous/supported catalysts, while revealing new, unexpected structural features of metallo-NHC supported substrates. It also highlights the potentially large diversity of surface sites present in functional materials prepared by surface chemistry, an essential knowledge to design materials with improved performances. |
| Databáze: | OpenAIRE |
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