Four Members of the Sandwich‐Type Polytungstophosphate Family Based on Pentalacunary [HPW 7 O 28 ] 8– Building Blocks

Four dimeric mononuclear sandwich‐type tungstophosphate clusters of Na 12 H[Fe III (HPW 7 O 28 ) 2 ] · 44H 2 O ( 1 ) and Na 14 [M(HPW 7 O 28 ) 2 ] · 44H 2 O {M = Co II ( 2 ), Cd II ( 3 ), Mn II ( 4 )} were successfully synthesized by reaction of Na 2 WO 4 · 2H 2 O, H 3 PO 4 , and CH 3 COOH with FeCl 3 · 6H 2 O, Co(CH 3 COO) 2 · 4H 2 O, CdSO 4 · 8H 2 O, and Mn(CH 3 COO) 2 · 4H 2 O, respectively. Single‐crystal X‐ray diffraction analysis revealed that 1 – 4 are essentially isomorphous and crystallize in the triclinic space group P $\bar {1}$ . Complexes 1 – 4 consist of two [HPW 7 O 28 ] 8– units incorporating a single Fe III , Co II , Cd II , and Mn II ion, respectively. Furthermore, the electrocatalytic behaviors of 1 – 4 in the reduction of nitrite were investigated.