《Table 1 Hydrogenation of nitrobenzene derivatives catalyzed by Au25@Ni-SiO2 (150) and Au25@Ni-SiO2

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《选择性控制的配体工程在金团簇催化中的作用（英文）》

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a.Reaction condition:2 mmol substrate，4 mmol Na BH4，30 mg immobilized catalyst（Au 6.1*10-3mmol），and 2 m L ethanol/2 m L H2O

The as-prepared catalysts were tested for functional group tolerance（Table 1）.Only the two opposite catalysts，Au25@Ni-SiO2（150）and Au25@Ni-SiO2（300），were compared，as they gave the sharpest contrast.It was observed that derivatives with electronwithdrawing groups（entries 1，4）were more active than those with electron-donating groups（entries 2 and3），since the room temperature was enough to convert the substrates over the catalysts.The results were consistent with previous patterns though some byproducts were generated.The Au25@Ni-SiO2（150）composite with S component gave rise to AXY derivatives as dominant products，while the other competitor yielded overwhelmed anilines.The steric effect from substrates was considerable as well.The groups on the para-positions didn’t interfere the contact between substrates and catalysts，and gave excellent conversion（entries2）.On the contrary，the groups on the ortho-position hindered the access to metal（entries 3 and 4），along with the exterior ligands of Au25@Ni-SiO2（150）blocking the substrate approaching the active sites，hence low conversion at ambient conditions.As a result，the conversion was too low to make big differences on the product preference.These systematic results comprehensively verified the ligand effect on the catalytic properties，including activity and selectivity as scheme1 illustrated.