An organic−inorganic hybrid polyoxometalate Na5H5.68 [Na0.17Rh0.83III(C6H8N2)2Cl2]2(C8H8N2)2[As4W40O140Rh4IV(C6H4N2S)2]⸱nH2O (1) containing 5.66 Rh atoms is prepared, to our knowledge, it owns the largest number of Rh atoms in the Rh-POMs family. Compound 1...

Three Ru-induced structural interconversion polyoxometalates (POMs), Na 13 H 5 [Ru 4 (H 2 O) 2 (Cl) 2 (WO 2 ) 4 (AsW 9 O 33 ) 4 ]• 43H 2 O (1), K 5 Na 9 H 8 [Ru 2 (WO 2 ) 4 (AsW 9 O 33 ) 4 ]•50H 2 O (2), and KNa 13 H 14 [(WO 2 ) 4 (AsW 9 O 33 ) 4 ]•34H 2 O (3), were successfully synthesized and thoroughly characterized. Interconversion of structures was accomplished by changing the number of active sites for compounds 1− 3. All three compounds contain one {As 4 W 40 O 140 } unit, showing similar structural characteristics except for the active center number (Ru).Interestingly, compound 1 [turnover number (TON)= 486; turnover frequency (TOF)= 20 h −1 ] showed highly efficient photocatalysis in achieving oxidative coupling of primary amines. Compound 2 (TON = 406, TOF = 17 h −1 ) was also found to promote the oxidative coupling with relatively poor efficiency; however, compound 3 (TON = 178; TOF = 7.4 h −1 ) had no obvious contribution to the coupling reaction system, and a chain of evidence indicates that the catalytic performances are strongly dependent on element contents of active sites. Furthermore, the Ru-containing POM-based photocatalysts are conveniently recyclable and reusable during the photocatalytic processes. This study demonstrates the possibility of tuning the catalytic efficiency and stability of POM-based photocatalysts by well designing and controlling their structures. The possible reaction mechanism for the photocatalysis synthesis of imine product is also proposed based on experimental studies.