Highly Distorted Uranyl Ion Coordination and One/Two-Dimensional Structural Relationship in the Ba2[UO2(TO4)2] (T = P, As) System: An Experimental and Compu

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• 作者：Shijun Wu ; Piotr M. Kowalski ; Na Yu ; Thomas Malcherek ; Wulf Depmeier ; Dirk Bosbach ; Shuao Wang ; Evgeny V. Suleimanov ; Thomas E. Albrecht-Schmitt ; Evgeny V. Alekseev
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：July 21, 2014
• 年：2014
• 卷：53
• 期：14
• 页码：7650-7660
• 全文大小：435K
• ISSN：1520-510X

文摘

Uranium compounds 伪-Ba₂[UO₂(PO₄)₂] (1), 尾-Ba₂[UO₂(PO₄)₂] (2), and Ba₂[UO₂(AsO₄)₂] (3) were synthesized by H₃BO₃/B₂O₃ flux reactions, though boron is not incorporated into the structures. Phases 1 and 2 are topologically identical, but 1 is heavily distorted with respect to 2. An unusual UO₇ pentagonal bipyramid occurs in 1, exhibiting a highly distorted equatorial configuration and significant bending of the uranyl group, due to edge-sharing with one neighboring PO₄^{3鈥?/sup> tetrahedron. Compound 2 contains more normal square bipyramids that share corners with four neighboring PO₄3鈥?/sup> tetrahedra, but the uranyl cation UO₂2+ is tilted relative to the equatorial plane. Experimental evidence as well as density functional theory (DFT) calculations suggest that 1 is more stable than 2. In theory, 1 and 2 can interconvert by forming/releasing the shared edge between the uranyl polyhedron and the phosphate tetrahedron. Similar fundamental building blocks in 尾-Ba₂[UO₂(PO₄)₂] and Ba₂[UO₂(AsO₄)₂] indicate a possible evolution of uranyl-based structures from chain to layer type and formation of an accretional series.}