Preferred Orientation of a Physisorbed Molecular Catalyst and Implications for Selectivity

ACS Physical Chemistry Au, Journal Year: 2025, Volume and Issue: unknown

Published: March 7, 2025

Language: Английский

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Trimethylaluminum Activates Zeolite-Confined Lanthanum Borohydrides to Enhance Catalytic C–H Borylation

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: April 3, 2025

AlMe3-treatment of the borylation precatalyst La(BH4)2(THF)2.5-Ph3Si-HY30 affords La(BH4)2(AlMe3)-Ph3Si-HY30, which is superior lanthanum-based for benzene with pinacolborane (HBpin), giving higher turnovers (>285) and improved yields (up to 42%) phenylpinacolborane (PhBpin). Solid-state NMR spectroscopy, X-ray adsorption theoretical studies characterized precatalytic sites in La(BH4)2(AlMe3)-Ph3Si-HY30 as κ2-O,O-{≡SiO(=Al)≡SiO}La(BH4)2(AlMe3), revealing that AlMe3 had displaced THF ligands. In contrast expected high reactivity THF-free organolanthanum, turnover frequency (TOF) PhBpin formation catalyzed by (2.7 h-1) slightly lower than untreated (3.6 h-1), implying a stronger inhibitor lanthanum. On other hand, inactive La(BH4)2(THF)2.2-SiO2 generates an active catalyst. also desorbs surface-O-BxHy species quenches residual Brønsted acid (BAS) silanols. Alumination BAS inhibits HBpin degradation, while alumination silanols creates reaction. The 8-fold inhibition BAS-catalyzed decomposition rate treatment gives kinetic advantage lanthanum-catalyzed C-H borylation, leading increased turnovers. Knowledge competing roles catalytic law enables identification favorable conditions low [HBpin] maximize or yield. Sterics affect selectivity substituted arenes heteroarenes, can proceed without precoordination donor. These steric effects, well having opposite effect on activity lanthanum HY vs SiO2, point confinement-activated sites.

Language: Английский

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Size matters: altering the metal-surface coordination in micropores via structural confinement effects

Inorganic Chemistry Frontiers, Journal Year: 2024, Volume and Issue: 11(20), P. 6862 - 6873

Published: Jan. 1, 2024

NMR experiments reveal how surface curvature can impact metal coordination. It was observed that under extreme confinement, secondary support–metal interactions are prevented, leading to a dynamic complex with an open coordination site.

Language: Английский

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Enhanced photocatalytic phenol production from benzene on polymers with coordinatively unsaturated Fe centers

Journal of Photochemistry and Photobiology A Chemistry, Journal Year: 2024, Volume and Issue: unknown, P. 116123 - 116123

Published: Oct. 1, 2024

Language: Английский

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