The synergic effects at the molecular level in CoS2 for selective hydrogenation of nitroarenes

Catalytic functionalized aniline formation from nitroarenes is a core technology in the synthesis of pharmaceuticals, agrochemicals, and fine chemicals. However, control of chemoselectivity still poses particular challenges with aromatic nitro substrates bearing one or more reducible groups. Here, we report the low-cost synthesis of a porous carbon supported CoS2 catalyst (CoS2/PC) and successfully apply the catalyst in the chemoselective hydrogenation of nitroarenes. For hydrogenation of 3-nitrostyrene, the catalyst furnishes a superior selectivity of 99% towards 3-aminostyrene at a conversion of >99%. Density functional theory calculations together with X-ray absorption fine structure spectroscopy reveal that terdentate and tetrahedral coordinated Co atoms in CoS2 (labeled as Co-3 and Co-4) are possible active sites. The face to face located Co-3 and Co-4 sites make the reaction rather local, and Co-3 and Co-4 sites are occupied by substrates and H-2, respectively, which is beneficial to the superior activity and selectivity. The Co-3-Co-4 "synergic active site pair" in CoS2 makes the investigation of the synergic effects at the molecular level a reality on heterogeneous catalysts.