Two novel Krebs-type polyoxoanions [CuI2(WO2)2(β-XW9O33)2]12− (X = SbIII, BiIII) resulting in 2D layer structures linked by copper(I) ions and copper(II) complex groups

Two sandwich-type organic–inorganic hybrid polyoxotungstates [enH2]5[CuII(en)2][CuI2(WO2)2(β-SbW9O33)2]·16H2O (1) and [enH2]5[CuII(en)2][CuI2(WO2)2(β-BiW9O33)2]·22H2O (2) (en = ethylenediamine) have been synthesized hydrothermally and structurally characterized by elemental analyses, IR spectra, thermal stability analyses, X-ray powder diffraction, and single-crystal X-ray diffraction. The polyoxoanions in 1 and 2 are composed of two trivacant (B-β-XW9O33)9− (X = SbIII (1), BiIII (2)) subunits joined together by two Cu(I) ions and two W(VI) ions resulting in two novel Krebs-type sandwich structures. These polyoxoanions are further connected by Cu(I) ions and [CuII(en)2]2+ coordination cations, and afford the first copper(I)-linked 2D layer structure constructed from Krebs-type polyoxotungstates. Additionally, the electrochemical behavior and electrocatalysis of 1 and 2 modified carbon paste electrodes (CPEs) have been studied. The results indicate that they have good electrocatalytic activities toward the reduction of nitrite.