An In‐Depth Mechanistic Study of Ru‐Catalysed Aqueous Methanol Dehydrogenation and Prospects for Future Catalyst Design. Issue 9 (30th March 2020)

• Record Type: Journal Article
• Authors: Govindarajan, Nitish; Sinha, Vivek; Trincado, Monica; Grützmacher, Hansjörg; Meijer, Evert Jan; de Bruin, Bas
• Is Part Of: ChemCatChem. Volume 12:Issue 9(2020)
• Page Start: 2610
• Page End: 2621
• Publication Date: 2020-03-30
• Subjects: methanol dehydrogenation -- explicit solvent -- DFT-MD -- ligand pKa; Catalysis -- Periodicals; 541.39505
• DOI: 10.1002/cctc.202000057
• Languages: English
• ISSNs: 1867-3880

Abstract

Abstract: Herein we provide mechanistic insights into the dehydrogenation of aqueous methanol catalysed by the [Ru(trop2 dae)] complex (which is in‐situ generated from [Ru(trop2 dad)], trop2 dad=1, 4‐bis(5H‐dibenzo[a, d]cyclohepten‐5‐yl)‐1, 4‐diazabuta‐1, 3‐diene), established by density functional theory based molecular dynamics (DFT‐MD) and static DFT calculations incorporating explicit solvent molecules. The aqueous solvent proved to participate actively in various stages of the catalytic cycle including the catalyst activation process, and the key reaction steps involving C−H activation and hydrogen production. The aqueous solvent forms an integral part of the reactive system for the C−H activation steps in the [Ru(trop2 dae)] system, with strong hydrogen bond interactions with the anionic oxygen (RO −, R=CH3, CH2 OH, HCO) and hydride moieties formed along the reaction pathway. In contrast to the [Ru(trop2 dad)] catalyst, C−H activation and hydrogen production does not proceed via a metal‐ligand cooperative pathway for the [Ru(trop2 dae)] system. The pKa of the coordinated amine donors in these complexes provides a rationale for the divergent reactivity, and the obtained mechanistic information provides new guidelines for the rational design of active and additive free catalytic systems for aqueous methanol dehydrogenation. Abstract : Methanol dehydrogenation : Mechanistic insights into the dehydrogenation of aqueous methanol catalysed by the [Ru(trop2 dae)] complex are established by density functional theory based molecular dynamics (DFT‐MD) and static DFT calculations incorporating explicit solvent molecules. The aqueous solvent proved to participate actively in various stages of the catalytic cycle including the catalyst activation process, and the key reaction steps involving C−H activation and hydrogen production.