Department of Chemistry, National Central University, Jhongli, Taiwan 320, Republic of China.
Inorg Chem. 2012 Mar 19;51(6):3879-82. doi: 10.1021/ic3000872. Epub 2012 Mar 5.
A pentavalent uranium germanate, Cs(3)UGe(7)O(18), was synthesized under high-temperature, high-pressure hydrothermal conditions at 585 °C and 160 MPa and structurally characterized by single-crystal X-ray diffraction and infrared spectroscopy. The valence state of uranium was confirmed by X-ray photoelectron spectroscopy and electron paramagnetic resonance. The room-temperature EPR spectrum can be simulated with two components using an axial model that are consistent with two distinct sites of uranium(V). In the structure of the title compound, each ([6])GeO(6) octahedron is bonded to six three-membered single-ring ([4])Ge(3)O(9)(6-) units to form germanate triple layers in the ab plane. Each layer contains nine-ring windows; however, these windows are blocked by adjacent layers. The triple layers are further connected by UO(6) octahedra to form a three-dimensional framework with intersecting six-ring channels along the <1 ̅10> directions. The Cs(+) cation sites are fully occupied, ordered, and located in the cavities of the framework. Pentavalent uranium germanates or silicates are very rare, and only two uranium silicates and one germanate analogue have been published. However, all of them are iso-structural with those of the Nb or Ta analogues. In contrast, the title compound adopts a new structural type and contains both four- and six-coordinate germanium. Crystal data of Cs(3)UGe(7)O(18): trigonal, P3̅c1 (No. 165), a = 12.5582(4) Å, c = 19.7870(6) Å, V = 2702.50(15) Å(3), Z = 6, D(calc) = 5.283 g·cm(-3), μ(Mo Kα) = 26.528 mm(-1), R(1) = 0.0204, wR(2) = 0.0519 for 1958 reflections with I > 2σ(I). GooF = 1.040, ρ(max,min) = 1.018, and -1.823 e·Å(-3).
一种五价铀锗酸盐，Cs(3)UGe(7)O(18)，是在 585°C 和 160 MPa 的高温高压水热条件下合成的，并通过单晶 X 射线衍射和红外光谱进行了结构表征。铀的价态通过 X 射线光电子能谱和电子顺磁共振确定。室温下的 EPR 谱可以用轴向模型模拟为两个分量，与铀(V)的两个不同位置一致。在标题化合物的结构中，每个([6])GeO(6)八面体与六个三员单环([4])Ge(3)O(9)(6-)单元键合，在 ab 平面形成锗酸盐三层。每层都包含九环窗口；然而，这些窗口被相邻的层阻塞。三层通过 UO(6)八面体进一步连接，形成一个具有沿<1 ̅10>方向相交的六元环通道的三维骨架。Cs(+)阳离子位置完全占据、有序并位于骨架的空腔中。五价铀锗酸盐或硅酸盐非常罕见，仅发表了两种铀硅酸盐和一种锗酸盐类似物。然而，它们都与 Nb 或 Ta 类似物的结构相同。相比之下，标题化合物采用了一种新的结构类型，同时包含四配位和六配位的锗。Cs(3)UGe(7)O(18)的晶体数据：三方，P3̅c1(No.165)，a=12.5582(4) Å，c=19.7870(6) Å，V=2702.50(15) Å(3)，Z=6，D(calc)=5.283 g·cm(-3)，μ(Mo Kα)=26.528 mm(-1)，R(1)=0.0204，wR(2)=0.0519，用于 1958 个反射，I>2σ(I)。GooF=1.040，ρ(max,min)=1.018，和-1.823 e·Å(-3)。
