A detailed mechanistic investigation is undertaken to facilitate the synthesis of ammonia through the reaction of molecular nitrogen and hydrogen, employing silicon-substituted cyclo[18]carbon (C₁₇Si) as a catalyst. Notably, the comprehensive catalytic cycle exhibits an overall negative Gibbs-free energy change, coupled with the regeneration of the catalyst. This study unveils the potential for ammonia synthesis under metal-free and mild reaction conditions.

Abstract

Activation of molecular nitrogen by silicon-substituted cyclo[18]carbon and its ability to produce the C₁₇Si-(NH₂)₂ derivative, as the precursor of NH₃, has been recently reported. This specific acquisition has piqued an interest to investigate the possibility of NH₃ formation with further addition of H₂ molecules in the gaseous reaction media. The current investigations reported in this article show that two moles of molecular H₂ generate two molecules of NH₃ and a C₁₇Si-H₂ byproduct from its precursor. The catalyst gets restored by an in situ reaction between some unreacted C₁₇Si-N₂ and the byproduct in the media. This reaction also produces the next C₁₇Si-(NH)₂ adduct, which restarts the catalytic cycle for NH₃ production again.