Syntheses, Crystal Structures and Electrochemical Properties of Three New One-dimensional Compounds Based on the BiW9O33 Unit

Three new one-dimensional compounds [{NaO2(H2O)2}2{(M(H2O)2)2(WO2)2- (BiW9O33)2}]·16H3O+·XH2O (M = MnII (1), CoII (2), NiII (3)) have been synthesized in an aqueous solution, and structurally characterized by elemental analysis, IR, TG and single-crystal X-ray diffraction. These tungstobismuthates reveal that one common feature is the trivacant β-B-BiW9O33 Keggin fragment as the structural building unit. Two β-B-BiW9O33 units are connected by two WO2 groups with further stabilization by the addition of two M(H2O)22+ groups leading to the M2Bi2W20 anions, which are linked in a 1-D chain by bisodium cluster. Electrochemical analyses show that compounds 1-3 display unique redox properties and good electrocatalytic activity to reduce nitrite.