Laboratoire des Multimatériaux et Interfaces, Université Lyon 1, Villeurbanne, CNRS, UMR 5615, Université de Lyon, F-69622, Lyon, France.
Inorg Chem. 2010 Jun 7;49(11):4830-5. doi: 10.1021/ic902525s.
The preparation of a new trisodium triborate, Na(3)[B(3)O(4)(OH)(4)], and its complete characterization in terms of molecular structure and thermal behavior are reported. Synthesis of this compound was achieved either by NaBH(4) hydrolysis or by thermal treatment of Na[B(OH)(4)].2H(2)O. The crystal structure was determined by single-crystal X-ray diffraction. The trisodium triborate crystallized in the monoclinic system (a = 12.8274(6) A, b = 7.7276(4) A, c = 6.9690(3) A, and beta = 98.161(3) degrees ), space group Cc, Z = 2. The structure of Na(3)[B(3)O(4)(OH)(4)] comprised B(3)O(4)(OH)(4) polyanions, based on B-O-containing rings with two tetracoordinated boron atoms and one tricoordinated boron atom in the fragments BO(2)(OH)(2) and BO(3), respectively. These polyanions are interconnected by four intermolecular hydrogen bonds and presented a tilt of 10.470(4) degrees compared to the a axis. Thus, they are stacked by rotation of about 180 degrees around an axis defined by the three-coordinated boron atoms and parallel to the c axis. Such polyanions were only observed previously in two synthetic compounds, M(3)[B(3)O(4)(OH)(4)].2H(2)O with M = K and Rb, which were isostructural. The originality of the present work was the synthesis and the description of a different crystallographic structure containing this polyanion. Characteristic peaks ranging from 500 to 1500 cm(-1) and around 3300 cm(-1) highlighted the presence of the B-O rings and hydroxyl groups, respectively. The decomposition temperature T = 155 degrees C was obtained by thermogravimetric analysis, and the following equivalent formula in terms of hydration degree was proposed: NaBO(2).(2)/(3)H(2)O. Na(3)[B(3)O(4)(OH)(4)] decomposed into Na(3)[B(3)O(5)(OH)(2)] in equilibrium with its vapor.
本文报道了一种新的三硼酸钠，Na(3)[B(3)O(4)(OH)(4)]的制备及其分子结构和热行为的完全表征。该化合物的合成方法有两种：一是通过 NaBH(4)水解，二是通过 Na[B(OH)(4)].2H(2)O 的热解。通过单晶 X 射线衍射确定了晶体结构。三硼酸钠在单斜晶系（a = 12.8274(6) A, b = 7.7276(4) A, c = 6.9690(3) A, 和 beta = 98.161(3) degrees ），空间群 Cc，Z = 2 中结晶。Na(3)[B(3)O(4)(OH)(4)]的结构由基于 B-O 含环的B(3)O(4)(OH)(4)多阴离子组成，该多阴离子包含两个四配位硼原子和一个三配位硼原子，分别在 BO(2)(OH)(2)和 BO(3)片段中。这些多阴离子通过四个分子间氢键相互连接，并相对于 a 轴倾斜 10.470(4)度。因此，它们通过大约 180 度的旋转堆积在由三配位硼原子定义的轴周围，并与 c 轴平行。这种多阴离子以前只在两个合成化合物 M(3)[B(3)O(4)(OH)(4)].2H(2)O 中观察到，其中 M = K 和 Rb，它们具有同构结构。本工作的创新性在于合成并描述了一种含有这种多阴离子的不同晶体结构。500 至 1500 cm(-1)和 3300 cm(-1)左右的特征峰分别突出了 B-O 环和羟基的存在。通过热重分析获得的分解温度 T = 155 摄氏度，并提出了以下关于水合度的等效公式：NaBO(2).(2)/(3)H(2)O。Na(3)[B(3)O(4)(OH)(4)]分解为 Na(3)[B(3)O(5)(OH)(2)]，与蒸气处于平衡状态。
