Tuning Polarity of Cu-O Bond in Heterogeneous Cu Catalyst to Promote Additive-free Hydroboration of Alkynes

Summary The concept of chemical bond polarity is well recognized; however, its tunability and corresponding effects on heterogeneous catalysis have never been discussed. Here, we report a method to control the polarity of the Cu-O bond in the heterogeneous Cu catalyst, and thus tune its activity for the hydroboration reaction. By synthetic procedure control, single-atomic-site Cu catalysts on ceria with more ionic Cu-O bonds (Cu1-O(I)/CeO2) and with more covalent Cu-O bonds (Cu1-O(C)/CeO2) can be obtained, respectively. The more ionic Cu-O bond makes Cu1-O(I)/CeO2 display a much higher activity than Cu1-O(C)/CeO2 in selective hydroboration of diverse alkynes with no additives, producing versatile vinylboronate compounds. The enhanced activity stems from the more ionic Cu-O bond facilitating the formation of key intermediate copper ethoxide species by dissociating ethanol molecules. These results may improve our understanding of the correlation between the nature of chemical bonds and catalytic properties and lead to better-performing heterogeneous catalysts.