Unprecedentedly high activity and selectivity for hydrogenation of nitroarenes with single atomic Co(1)-N(3)P(1) sites

Transition metal single atom catalysts (SACs) with M(1)-N(x) coordination configuration have shown outstanding activity and selectivity for hydrogenation of nitroarenes. Modulating the atomic coordination structure has emerged as a promising strategy to further improve the catalytic performance. Herein, we report an atomic Co(1)/NPC catalyst with unsymmetrical single Co(1)-N(3)P(1) sites that displays unprecedentedly high activity and chemoselectivity for hydrogenation of functionalized nitroarenes. Compared to the most popular Co(1)-N(4) coordination, the electron density of Co atom in Co(1)-N(3)P(1) is increased, which is more favorable for H(2) dissociation as verified by kinetic isotope effect and density functional theory calculation results. In nitrobenzene hydrogenation reaction, the as-synthesized Co(1)-N(3)P(1) SAC exhibits a turnover frequency of 6560 h(−1), which is 60-fold higher than that of Co(1)-N(4) SAC and one order of magnitude higher than the state-of-the-art M(1)-N(x)-C SACs in literatures. Furthermore, Co(1)-N(3)P(1) SAC shows superior selectivity (>99%) toward many substituted nitroarenes with co-existence of other sensitive reducible groups. This work is an excellent example of relationship between catalytic performance and the coordination environment of SACs, and offers a potential practical catalyst for aromatic amine synthesis by hydrogenation of nitroarenes.