“Activated Borane” – A Porous Borane Cluster Polymer as an Efficient Lewis Acid-based Catalyst

Abstract

Borane cluster based porous covalent networks, named activated borane (ActB), were prepared by co-thermolysis of decaborane(14) (nido-B10H14) and selected hydrocarbons (toluene – ActB-Tol, cyclohexane – ActB-cyHx, and n-hexane – ActB-nHx) under anaerobic conditions. These amorphous solid powders exhibit different textural and Lewis acid (LA) properties that vary depending on the nature of the constituent organic linker. For ActB-Tol, its LA strength even approaches that of the commonly-used molecular LA, B(C6F5)3. Most notably, ActBs can act as heterogeneous LA catalysts in hydrosilylation/deoxygenation reactions with various carbonyl substrates, as well as in the gas-phase dehydration of ethanol. These studies reveal the excellent potential of ActBs in catalytic applications, showing a) the possibility for tuning catalytic reaction outcomes (selectivity) in hydrosilylation/deoxygenation reactions by changing the material’s composition, and b) the very high activity toward ethanol dehydration that exceeds commonly used γ-Al2O3 by achieving a stable conversion of ~93 % with a selectivity for ethylene production of ~78 % during a 17 h continuous period on stream at 240°C.