A La-containing poly(polyoxometalate) simultaneously comprising tungstoantimonate and tungstobismuthate segments: synthesis, structure and catalysis

Abstract

A novel La-containing octameric polyoxotungstate, [H₂N(CH₃)₂]₈Na₁₂H₁₆[{(WO₂)₂(WO₃)₂(B-β-BiW₉O₃₃)₂}{Bi₆O₃(OH)₃La₃(H₂O)₆ (CO₃)(B-α-SbW₉O₃₃)₃}₂]·52H₂O (1), has been synthesized under weakly acidic aqueous solution conditions, and further structurally characterized by carrying out single-crystal X-ray diffraction, powder X-ray diffraction, IR spectrometry and thermogravimetric analyses. The polyoxoanion of 1 consists of a Krebs-type tungstobismuthate cluster, namely (WO₂)₂(WO₃)₂(B-β-BiW₉O₃₃)₂, connecting two identical trimeric tungstoantimonate units, namely Bi₆O₃(OH)₃La₃(H₂O)₆(CO₃)(B-α-SbW₉O₃₃)₃. Furthermore, compound 1 as a heterogeneous catalyst, with H₂O₂ as the oxidant, can effectively accelerate the oxidative degradation of 2-chloroethyl ethyl sulfide (CEES) into 2-chloroethyl ethyl sulfoxide (CEESO), demonstrating high conversion and selectivity, as well as good recyclability and stability. This work has expanded the structural diversity of lanthanide-incorporated polyoxometalates containing hybrid POM fragments and has applied such a compound to the selective oxidation of CEES.