Dihydrogen activation by antiaromatic pentaarylboroles.
Facile metal-free splitting of molecular hydrogen (H(2)) is crucial for the utilization of H(2) without the need for toxic transition-metal-based catalysts. Frustrated Lewis pairs (FLPs) are a new class of hydrogen activators wherein interactions with both a Lewis acid and a Lewis base heterolytically disrupt the hydrogen-hydrogen bond. Here we describe the activation of hydrogen exclusively by a boron-based Lewis acid, perfluoropentaphenylborole. This antiaromatic compound reacts extremely rapidly with H(2) in both solution and the solid state to yield boracyclopent-3-ene products resulting from addition of hydrogen atoms to the carbons alpha to boron in the starting borole. The disruption of antiaromaticity upon reaction of the borole with H(2) provides a significant thermodynamic driving force for this new metal-free hydrogen-splitting reaction.
Fan
Cheng
C
Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4.
Mercier
Lauren G
LG
Piers
Warren E
WE
Tuononen
Heikki M
HM
Parvez
Masood
M
D001895:Boron / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D013816:Thermodynamics
D006859:Hydrogen; D001895:Boron