Spatial intimacy of binary active-sites for selective sequential hydrogenation-condensation of nitriles into secondary imines.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 34099687.
- Also identified by DOI 10.1038/s41467-021-23705-9 and PMC identifier 8184996.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Precisely controlling the spatial intimacy of multiple active sites at sub-nanoscale in heterogeneous catalysts can improve their selectivity and activity. Herein, we realize a highly selective nitrile-to-secondary imine transformation through a cascaded hydrogenation and condensation process by Pt<sub>1</sub>/CoBO<sub>x</sub> comprising the binary active sites of the single-dispersed Pt and interfacial Lewis acidic B. Atomic Pt sites with large inter-distances (>nanometers) only activate hydrogen for nitrile hydrogenation, but inhibit condensation. Both adjacent B…B on CoBO<sub>x</sub> and neighbouring Pt…B pairs with close intimacy of ~0.45 nm can satisfy the spatial prerequisites for condensation. Mechanism investigations demonstrate the energetically favorable pathway occurred on adjacent Lewis acidic B sites through the nitrile adsorption (acid-base interaction), hydrogenation via hydrogen spillover from Pt to B sites and sequential condensation. Strong intermolecular tension and steric hindrance of secondary imines on active sites lead to their effective desorption and thereby a high chemoselectivity of secondary imines.