La[B5O8(OH)(H2O)]NO3•2H2O的合成与结构

采用熔融硼酸法合成了一种具有层状结构的新型水合稀土多硼酸盐, LaB₅O₈(OH)(H₂O)]NO₃?2H₂O, 并利用单晶X射线衍射技术确定了它的结构. 它属于单斜晶系, P21/n空间群. 其基本构建单元 (fundamental building block, 简称FBB)是由三个BO4和两个BO3基团所构成的一个双三元环B5O12]基团. 结构中每一个FBB通过共顶点氧原子与周围四个同样的单元连接成具有九元环窗口的二维B5O10]层, La³⁺位于九元环中心附近. B5O10]层沿着b方向进行堆积, 硝酸根离子和结构中部分结晶水分子位于相邻的B5O10]层之间.

Synthesis and Structure of La[B5O8(OH)(H2O)]NO3·2H2O

Boric acid is used as a flux and reactant to synthesize a novel hydrated rare earth polyborate, LaB₅O₈(OH)(H₂O)]NO₃?2H₂O. The structure of the title compound is established by single X-ray diffraction data. It crystallizes in monoclinic structures (P21/n) and consists of a double three-membered ring composed of three BO4 and two BO3 groups as the fundamental building block (FBB). The FBB shares four common oxygen atoms with thethe adjacent FBBs producing a borate layer containing nine-membered borate ring window. Lanthanum cations are located around the center of the nine-membered ring. The borate layers are stacked along the b axis and are interlinked by the La－O bond. Nitrate ions and some water molecules are sandwiched between the borate layers. This study further demonstrates that the low temperature synthesis approach by using molten boric acid as a flux is effective for the syntheses of hydrated rare earth polyborates.