Two sandwich-type uranyl-containing polytungstates catalyze aerobic synthesis of benzimidazoles

Diversified synthetic strategies are extremely important for the structural diversity of uranium-containing polyoxometalates (U-POMs) and their functional expansion. Herein, two sandwich-type U-POMs were reported, which are Na5.6K6.4[(UO2)(H2O)(TeW9O33)]2·21H2O (UTeW9) and Na8.9K2.7H1.19[K0.79(UO2)2.21(PW9O34)2]·12H2O (UPW9) using in-situ strategy and lacunary precursor strategy, respectively. UTeW9 shows a typical Keggin-type open or half-sandwich configuration. UPW9 shows a typical Keggin-type sandwiched structure containing significant disorders of K(I) and uranyl ions with a triangular configuration. In addition, UTeW9 exhibits high efficiency in the catalyzed condensation of various o-arylenediamines and aldehydes for the aerobic synthesis of benzimidazoles with excellent yield.