Two Dawson-type U(VI)-containing selenotungstates with sandwich structure and its high‐efficiency catalysis for pyrazoles

Two novel uranium-containing selenotungstates Na 3 [H 19 (UO 2 ) 2 ( μ 2 O)(Se 2 W 14 O 52 ) 2 ]·41H 2 O ( U 2 ) and (NH 4 ) 10 [H 4 (SeO) 2 (UO 2 ) 2 (H 2 O) 2 (H 2 Se 2 W 14 O 52 )(Se 2 W 14 O 52 )]·66H 2 O ( Se 2 U 2 ) based on the {Se 2 W 14 O 52 } unit were successfully prepared and fully characterized. To our knowledge, the uranium is firstly introduced into the selenotungstates. Moreover, it is notable that U 2 exhibits excellent Lewis acid-base catalytic activities in the condensation cyclization of sulfonyl hydrazides with diketones to synthesize polysubstituted pyrazoles. All the desired products were obtained in moderate to good yields (up to 99%).