Polymorphism in Alkali Metal Uranyl Nitrates: Synthesis and Crystal Structure of γ‐K(UO2)(NO3)3
Polymorphism in Alkali Metal Uranyl Nitrates: Synthesis and Crystal Structure of γ‐K(UO2)(NO3)3
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碱金属硝酸铀酰的多晶型：γ-K(UO2)(NO3)3 的合成和晶体结构
DOI：
10.1002/zaac.201100200
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
P. Burns
中科院分区：
文献类型：
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作者：
L. Jouffret;S. Krivovichev;P. Burns
用蒸发法从水溶液中制备了γ-K（UO_4）（NO_3）_4单晶。晶体结构[正交晶系，Pbca（61），a = 9.2559（3）A，B = 12.1753（3）A，c = 15.8076（5）A，V = 1781.41（9）A³，Z = 8]用直接法测定，并根据3657个独特的观察反射，修正到R = 0.0267。其结构由孤立的阴离子三硝酸铀酰单元[（UO <$）（NO <$）<$]-组成，它们通过十一配位的K+阳离子连接。K（UO <$）（NO <$）<$的两种已知的多晶型物（α-和γ-相）可以被认为是基于被K+阳离子分离的孤立的络合物[（UO <$）（NO <$）<$]-离子的片。两种K[UO]多晶型的存在是由于三硝酸铀酰团簇的二维排列方式相同，三维排列方式不同所致。
Single crystals of γ-K(UO₂)(NO₃)₃ were prepared from aqueous solutions by evaporation. The crystal structure [orthorhombic, Pbca (61), a = 9.2559(3) A, b = 12.1753(3) A, c = 15.8076(5) A, V = 1781.41(9) A³, Z = 8] was determined by direct methods and refined to R₁ = 0.0267 on the basis of 3657 unique observed reflections. The structure is composed of isolated anionic uranyl trinitrate units, [(UO₂)(NO₃)₃]–, that are linked through eleven-coordinated K+ cations. Both known polymorphs of K(UO₂)(NO₃)₃ (α- and γ-phases) can be considered as based upon sheets of isolated complex [(UO₂)(NO₃)₃]– ions separated by K+ cations. The existence of polymorphism in the two K[UO₂(NO₃)₃] polymorphs is due to the different packing modes of uranyl trinitrate clusters that adopt the same two-dimensional but different three-dimensional arrangements.