A Ni-added polyoxometalate: synthesis, structure and catalytic performance

Due to “lacunary-directed” effect, two SiW 10 fragments induce Ni 2+ ions and further react H 3 BO 3 to form [{BO(OH) 2 } 2 Ni 6 (OH)(H 2 O) 6 (SiW 10 O 37 ) 2 ] 9− cluster, catalyzing Knoevenagel condensation efficiently.