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 Co₃ and Co₄) are possible active sites. The face to face located Co₃ and Co₄ sites make the reaction rather local, and Co₃ and Co₄ sites are occupied by substrates and H₂, respectively, which is beneficial to the superior activity and selectivity. The Co₃-Co₄ "synergic active site pair" in CoS₂ makes the investigation of the synergic effects at the molecular level a reality on heterogeneous catalysts.