Department of Chemistry, National Central University, Jhongli, Taiwan 320, Republic of China.
Inorg Chem. 2013 Jun 17;52(12):7230-5. doi: 10.1021/ic400854j. Epub 2013 May 31.
A salt-inclusion mixed-valence uranium(V,VI) silicate, [Na9F2][(U(V)O2)(U(VI)O2)2(Si2O7)2], was synthesized under hydrothermal conditions at 585 °C and 160 MPa and structurally characterized by powder and single-crystal X-ray diffraction (XRD). The valence states of uranium were established by U 4f X-ray photoelectron spectroscopy (XPS). The structure contains two-dimensional (2D) sheets of uranyl disilicate with the composition [UO2Si2O7], which are connected by U(1)(V)O6 tetragonal bipyramids to form thick layers. The Na(+) cations are located at sites in the intralayer and interlayer regions. In addition to Na(+) cations, the interlayer region also contains F(-) anions such that infinite chains with the formula FNa1/1Na4/2 are formed. The same type of chain was observed in K2SnO3. The title compound is not only the first example of salt-inclusion metal silicate synthesized under high-temperature, high-pressure hydrothermal conditions, as well as the first salt-inclusion mixed-valence uranium silicate, but it is also the first mixed-valence uranium(V,VI) silicate in the literature. Crystal data: [Na9F2][(U(V)O2)(U(VI)O2)2(Si2O7)2], triclinic, P1 (No. 2), a = 5.789(1) Å, b = 7.423(2) Å, c = 12.092(2) Å, α = 90.75(3)°, β = 96.09(3)°, γ = 90.90(3)°, V = 516.5(2) Å(3), Z = 1, R1 = 0.0241, and wR2 = 0.0612.
一种含盐混合价态铀（V，VI）硅酸盐，[Na9F2][(U(V)O2)(U(VI)O2)2(Si2O7)2]，是在 585°C 和 160 MPa 的水热条件下合成的，并通过粉末和单晶 X 射线衍射（XRD）进行了结构表征。铀的价态通过 U 4f X 射线光电子能谱（XPS）确定。结构包含二维（2D）层状的铀二硅酸盐，其组成[UO2Si2O7]，由 U(1)(V)O6 四方双锥连接形成厚层。Na(+)阳离子位于层内和层间区域的位置。除了 Na(+)阳离子外，层间区域还含有 F(-)阴离子，从而形成具有化学式 FNa1/1Na4/2 的无限链。在 K2SnO3 中也观察到了相同类型的链。标题化合物不仅是在高温高压水热条件下合成的首例含盐金属硅酸盐，也是首例含盐混合价态铀硅酸盐，而且也是文献中首例混合价态铀（V，VI）硅酸盐。晶体数据：[Na9F2][(U(V)O2)(U(VI)O2)2(Si2O7)2]，三斜晶系，P1（No. 2），a = 5.789(1) Å，b = 7.423(2) Å，c = 12.092(2) Å，α = 90.75(3)°，β = 96.09(3)°，γ = 90.90(3)°，V = 516.5(2) Å(3)，Z = 1，R1 = 0.0241，wR2 = 0.0612。
