Unexpected activity of MgO nanoclusters for the reductive-coupling synthesis of organonitrogen chemicals with C = N bonds.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 40140389.
- Also identified by DOI 10.1038/s41467-025-58222-6 and PMC identifier 11947229.
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Abstract
Reductive-coupling of nitro compounds and alcohols is a sustainable route for constructing C = N bonds in organonitrogen chemicals, yet challenging due to the inertness of α-C<sub>sp3</sub>-H bond in alcohols and the vulnerability of C = N bonds towards hydrogenation. Here, we report the surprising catalytic activity of ultrafine alkaline-earth metal oxide MgO nanoclusters (0.9 ± 0.3 nm) that efficiently activate α-C<sub>sp3</sub>-H bonds, facilitating the transfer hydrogenation and synthesis of value-added chemicals bearing C = N bonds with high to excellent yields (86-99%). Controlled experiments and characterizations showed the crucial role of oxygen vacancies (O<sub>v</sub>) and local Mg environment (Mg-O bond) in MgO for substrate adsorption and activation via electronic interactions between substrate's negatively charged oxygen atoms and O<sub>v</sub> sites in MgO nanoclusters. Theoretical calculation further confirmed that O<sub>v</sub> significantly lowered the energy barrier of the hydrogen atom transfer from α-C<sub>sp3</sub>-H in ethanol to the nitro group in nitrobenzene (29.3 vs. 52.9 kcal/mol), which is the rate-determining step with the highest energy barrier in reductive-coupling reactions. Our method not only provides an efficient and sustainable pathway for synthesizing organonitrogen chemicals with C = N bonds but also inspires the exploration of main group element catalysts as alternatives to transition metal and noble metal catalysts for organic transformations.