Novel Lewis Acid‐Base Interactions in Polymer‐Derived Sodium‐Doped Amorphous Si−B−N Ceramic: Towards Main‐Group‐Mediated Hydrogen Activation

Abstract Interest is growing in transition metal‐free compounds for small molecule activation and catalysis. We discuss the opportunities arising from synthesizing sodium‐doped amorphous silicon‐boron‐nitride (Na‐doped a‐SiBN). Na + cations and 3‐fold coordinated B III moieties were incorporated into an amorphous silicon nitride network via chemical modification of a polysilazane followed by pyrolysis in ammonia (NH 3 ) at 1000 °C. Emphasis is placed on the mechanisms of hydrogen (H 2 ) activation within Na‐doped a‐SiBN structure. This material design approach allows the homogeneous distribution of Na + and B III moieties surrounded by SiN 4 units contributing to the transformation of the B III moieties into 4‐fold coordinated geometry upon encountering H 2 , potentially serving as frustrated Lewis acid (FLA) sites. Exposure to H 2 induced formation of frustrated Lewis base (FLB) N − = sites with Na + as a charge‐compensating cation, resulting in the in situ formation of a frustrated Lewis pair (FLP) motif (≡B FLA ⋅⋅⋅H δ− ⋅⋅⋅H δ+ ⋅⋅⋅:N − (Na + )=). Reversible H 2 adsorption‐desorption behavior with high activation energy for H 2 desorption (124 kJ mol −1 ) suggested the H 2 chemisorption on Na‐doped a‐SiBN. These findings highlight a future landscape full of possibilities within our reach, where we anticipate main‐group‐mediated small molecule activation will have an important impact on the design of more efficient catalytic processes and the discovery of new catalytic transformations.