3-Dimensional Methylammonium and Ammonium Templated Lithiumberyllofluoro Frameworks

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• 作者：Lee A. Gerrard and Mark T. Weller
• 刊名：Chemistry of Materials
• 出版年：2004
• 出版时间：May 4, 2004
• 年：2004
• 卷：16
• 期：9
• 页码：1650 - 1659
• 全文大小：489K
• 年卷期：v.16,no.9(May 4, 2004)
• ISSN：1520-5002

文摘

Two three-dimensional lithiumberyllofluoride materials, of the same framework stoichiometry but different topologies, have been synthesized using hydrothermal pressureconditions and ammonium/methylammonium cations as structure-directing species. Compound I, [Li₂Be₂F₇][NH₄], and compound II, [Li₂Be₂F₇][CH₃NH₃], both crystallize in orthorhombic space groups: Pca2₁ for I and Cmcm for II. Single crystal analysis reveals that thematerials have slightly different 3-D framework topologies for the [Li₂Be₂F₇] frameworkcomposed of [LiF₄] and [BeF₄] tetrahedra connected through doubly and triply bridgingfluorides. Both networks can be viewed as sheets formed of 3- and 4-nets that linkperpendicular to the sheet, through a bridging fluoride, to form six-membered interlayerpores. The six-membered channels contain the amine species hydrogen-bonded to frameworkfluoride ions surrounding the interior of the pore. The thermal stability, spectroscopicproperties, and both powder X-ray and neutron data of these compounds are reported, alongwith the single-crystal analysis used to solve the structures.