40Ni-Added Poly(polyoxometalate) Assembled by {Ni 6 GeW 9 } and {Ni 8 (GeW 9 ) 2 } Units: Structure, Magnetic, and Heterogeneous Catalysis Properties.

A novel 40Ni-added germanotungstate, Cs 8 K 14 Na 3 H 3 {[Ni 6 (OH) 3 (H 2 O) 6 (B-α-GeW 9 O 34 )] 2 [Ni 8 (μ 6 -O)(μ 2 -OH) 2 (μ 3 -OH) 2 (H 2 O)B 2 O 3 (OH) 2 (B-α-GeW 9 O 34 ) 2 ]} 2 ·84H 2 O ( 1 ), was made by the reaction of the trivacant [A-α-GeW 9 O 34 ] 10- ({GeW 9 }) precursor with Ni 2+ cations and B 5 O 8 - , and systematically investigated by Fourier-transform infrared spectroscopy, elemental analysis, thermogravimetric analysis, and powder X-ray diffraction. Single crystal X-ray analysis indicates that the polyoxoanion of 1 is a novel octamer constructed by {Ni 6 GeW 9 } and {Ni 8 (GeW 9 ) 2 } structural building units via Ni-O═W linkages. The magnetic behavior shows the existence of overall ferromagnetic interactions among the Ni 2+ centers in compound 1 . Photocatalytic H 2 production studies have implied that 1 can work as a heterogeneous catalyst for hydrogen production with decent robustness and recyclability.