Boosting Effect of Sterically Protected Glucosyl Substituents in Formic Acid Dehydrogenation by Iridium(III) 2-Pyridineamidate Catalysts.

Autor: Trotta C; Department of Chemistry, Biology and Biotechnology and CIRCC, University of Perugia, Via Elce di Sotto 8, 06123, Perugia, Italy., Langellotti V; Department of Chemical Sciences and CIRCC, University of Napoli Federico II, Via Cintia 21, 80126, Napoli, Italy., Manco I; Department of Chemical Sciences and CIRCC, University of Napoli Federico II, Via Cintia 21, 80126, Napoli, Italy., Rodriguez GM; Department of Chemistry, Biology and Biotechnology and CIRCC, University of Perugia, Via Elce di Sotto 8, 06123, Perugia, Italy., Rocchigiani L; Department of Chemistry, Biology and Biotechnology and CIRCC, University of Perugia, Via Elce di Sotto 8, 06123, Perugia, Italy., Zuccaccia C; Department of Chemistry, Biology and Biotechnology and CIRCC, University of Perugia, Via Elce di Sotto 8, 06123, Perugia, Italy., Ruffo F; Department of Chemical Sciences and CIRCC, University of Napoli Federico II, Via Cintia 21, 80126, Napoli, Italy., Macchioni A; Department of Chemistry, Biology and Biotechnology and CIRCC, University of Perugia, Via Elce di Sotto 8, 06123, Perugia, Italy.
Jazyk: angličtina
Zdroj: ChemSusChem [ChemSusChem] 2024 Oct 21; Vol. 17 (20), pp. e202400612. Date of Electronic Publication: 2024 Jun 07.
DOI: 10.1002/cssc.202400612
Abstrakt: [Cp*Ir(R-pica)Cl] (Cp*=pentamethylcyclopentadienyl anion, pica=2-picolineamidate) complexes bearing carbohydrate substituents on the amide nitrogen atom (R=methyl-β-D-gluco-pyranosid-2-yl, 1; methyl-3,4,6-tri-O-acetyl-β-D-glucopyranosid-2-yl, 2) were tested as catalysts for formic acid dehydrogenation in water. TOF MAX values over 12000 h -1 and 50000 h -1 were achieved at 333 K for 1 and 2, respectively, with TON values over 35000 for both catalysts. Comparison with the simpler cyclohexyl-substituted analogue (3) indicated that glucosyl-based complexes are much better performing under the same experimental conditions (TOF MAX =5144 h -1 , TON=5000 at pH 2.5 for 3) owing to a lower tendency to isomerize to the less active k 2 -N,O isomer upon protonation. The 5-fold increase in TOF MAX observed for 2 with respect to 1 is reasonably due to an optimal steric protection by the acetyl substituent, which may prevent unproductive inner-sphere reactivity. These results showcase a powerful strategy for the inhibition of the common deactivation pathways of [Cp*Ir(R-pica)X] catalysts for FA dehydrogenation, paving the way for the development of better performing hydrogen storage systems.
(© 2024 Wiley-VCH GmbH.)
Databáze: MEDLINE
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