Synthesis, Structural Elucidation, and Catalytic Properties in Olefin Epoxidation of the Polymeric Hybrid Material [Mo3O9(2-[3(5)-Pyrazolyl]pyridine)]n

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• 作者：Tatiana R. Amarante ; Patr铆cia Neves ; Ana C. Gomes ; Mariela M. Nolasco ; Paulo Ribeiro-Claro ; Ana C. Coelho ; Anabela A. Valente ; Filipe A. Almeida Paz ; Stef Smeets ; Lynne B. McCusker ; Martyn Pillinger ; Isabel S. Gon莽alves
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：March 3, 2014
• 年：2014
• 卷：53
• 期：5
• 页码：2652-2665
• 全文大小：743K
• 年卷期：v.53,no.5(March 3, 2014)
• ISSN：1520-510X

文摘

The reaction of [MoO₂Cl₂(pzpy)] (1) (pzpy = 2-[3(5)-pyrazolyl]pyridine) with water in an open reflux system (16 h), in a microwave synthesis system (120 掳C, 2 h), or in a Teflon-lined stainless steel digestion bomb (100 掳C, 19 h) gave the molybdenum oxide/pyrazolylpyridine polymeric hybrid material [Mo₃O₉(pzpy)]_n (2) as a microcrystalline powder in yields of 72鈥?9%. Compound 2 can also be obtained by the hydrothermal reaction of MoO₃, pzpy, and H₂O at 160 掳C for 3 d. Secondary products isolated from the reaction solutions included the salt (pzpyH)₂(MoCl₄) (3) (pzpyH = 2-[3(5)-pyrazolyl]pyridinium), containing a very rare example of the tetrahedral MoCl₄^{2鈥?/sup> anion, and the tetranuclear compound [Mo₄O₁₂(pzpy)₄] (4). Reaction of 2 with excess tert-butylhydroperoxide (TBHP) led to the isolation of the oxodiperoxo complex [MoO(O₂)₂(pzpy)] (5). Single-crystal X-ray structures of 3 and 5 are described. Fourier transform (FT)-IR and FT Raman spectra for 1, 4, and 5 were assigned based on density functional theory calculations. The structure of 2 was determined from synchrotron powder X-ray diffraction data in combination with other physicochemical information. In 2, a hybrid organic鈥搃norganic one-dimensional (1D) polymer, _{鈭?/sub>1[Mo3O9(pzpy)], is formed by the connection of two very distinct components: a double ladder-type inorganic core reminiscent of the crystal structure of MoO3 and 1D chains of corner-sharing distorted {MoO4N2} octahedra. Compound 2 exhibits moderate activity and high selectivity when used as a (pre)catalyst for the epoxidation of cis-cyclooctene with TBHP. Under the reaction conditions used, 2 is poorly soluble and is gradually converted into 5, which is at least partly responsible for the catalytic reaction.}}