Self-Assembly of a U(VI)-Containing Polytungstate Tetramer with Lewis Acid-Base Catalytic Activity for a Dehydration Condensation Reaction

Yu-Feng Liu; Ke Li; Hui-Yong Lian; Xue-Jiao Chen; Xing-Lei Zhang; Guo-Ping Yang

doi:10.1021/acs.inorgchem.2c02918

Self-Assembly of a U(VI)-Containing Polytungstate Tetramer with Lewis Acid-Base Catalytic Activity for a Dehydration Condensation Reaction

Inorg Chem. 2022 Dec 19;61(50):20358-20364. doi: 10.1021/acs.inorgchem.2c02918. Epub 2022 Nov 2.

Authors

Yu-Feng Liu^{1

2}, Ke Li¹, Hui-Yong Lian¹, Xue-Jiao Chen¹, Xing-Lei Zhang¹, Guo-Ping Yang¹

Affiliations

¹ Jiangxi Province Key Laboratory of Synthetic Chemistry, Jiangxi Key Laboratory for Mass Spectrometry and Instrumentation, East China University of Technology, Nanchang 330013, China.
² Guangdong Provincial Key Lab of Green Chemical Product Technology, Guangzhou 510640, China.

PMID: 36322943
DOI: 10.1021/acs.inorgchem.2c02918

Abstract

A novel U(VI)-containing polytungstate (U-POW) tetramer, {K_1.37Na_26.63[K₂(UO₂)₄Cl_0.5(OH)_5.5(γ-SiW₁₀O₃₆)₄]}·ca66H₂O (U₄), was synthesized using the Keggin-type precursor [γ-SiW₁₀O₃₆]^8- and UO₂(NO₃)₂. U₄ was further characterized by single-crystal X-ray diffraction, FT-IR, Raman spectroscopy, solid-state diffuse reflection spectroscopy, ICP-OES, ESI-MS, TGA, and PXRD. The central {K₂(UO₂)₄Cl_0.5(OH)_5.5} chromophore was constructed dexterously from four uranyl, four halves of K ions, 5.5 bridging μ₂-OH, and disordered Cl ions, and was further stabilized by four {γ-SiW₁₀} moieties to construct the tetramer [K₂(UO₂)₄Cl_0.5(OH)_5.5(γ-SiW₁₀O₃₆)₄]^28-. Notably, U₄ could work as an effective bifunctional Lewis acid-base catalyst for the synthesis of pyrazoles via the condensation of hydrazines with 1,3-diketones under mild conditions, which is attributed to the synergetic effect of the Lewis acidity of U(VI) and the Lewis basicity of {γ-SiW₁₀}.