每周分子 | Molecule of the Week

Original ACS 美国化学会 ACS美国化学会 2022-07-01

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每周分子：十二硼酸铯

Molecule of the Week:

Cesium dodecaborate

十二硼酸铯是众多已知聚硼烷阴离子盐之一。十二硼酸根阴离子具有正八面体形状，是五种柏拉图固体之一。十二硼酸盐与十二面烷是等电子的。

1960 年，罗门哈斯红石兵工厂(Rohm and Haas’s Redstone Arsenal，亨茨维尔，美国阿拉巴马州)研究部门的Anthony R. Pitochelli和M. Frederick Hawthorne制备了少量的几种十二硼酸盐。这些盐含有三甲基铵、钾离子和三苯基甲基鏻阳离子。

十年后，杜邦(威尔明顿，美国特拉华州)的Henry C. Miller和Earl L. Muetterties开发了铯盐的合成方法。如1967年出版的《Borane Anions》一书所述，由硼氢化钠(NaBH₄)与三氟化硼(BF₃)反应生成三硼酸盐NaB₃H₈，然后将三硼酸盐热解，得到含有十二硼酸钠的混合物, 再通过引入铯离子获得十二硼酸铯。

斯图加特大学(德国)的Thomas Schlied及其同事们于2000年报道了十二硼酸铯的晶体结构。该晶体为无色、B-B距离为178 pm、B-H 距离为112 pm的多面立方体。每个铯离子与12个氢原子连接，与每个氢原子的距离为313pm。

近年来，科学家们一直在探索十二硼酸盐的实际用途，例如在电池电极、催化和传感器中的应用。特别是武汉大学的张海波和周晓海领导的研究小组已经使用十二硼酸铯制备出复杂的催化剂。

2018年，研究人员报道了一类具有“覆盆子状”结构的核壳磁性金纳米复合材料的制备。十二硼酸铯在制备高度单分散的金纳米粒子(AuNPs)和将AuNPs固定在γCD@Fe₃O₄底物的表面上具有双重作用。所得的 AuNPs@Fe₃O₄复合材料制成了高活性和可回收的催化剂，用于将硝基芳族化合物选择性还原为对应的苯胺。

两年后，该研究小组发现，在温和(50°C)条件下，用十二硼酸铯包覆的立方铂纳米粒子可以催化过氧化氢和氧气，将甲烷直接氧化为乙醇。优化后的反应生成乙醇的转化率>97%。

十二硼酸铯信息速览

CAS 登记号	12008-75-2
SciFinder命名	Dodecaborate(2–), dodecahydro-, cesium (1:2)
分子式	B₁₂Cs₂H₁₂
摩尔质量	407.64 g/mol
外观	白色晶体或粉末
熔点	>650 ºC
水溶性	微溶

十二硼酸铯危害信息

GHS*分类：易燃固体，类别1
H228-易燃固体
GHS分类：皮肤腐蚀/刺激，类别2
H315-引起皮肤刺激
GHS分类：严重眼损伤/眼刺激，类别2A
H319-引起严重眼睛刺激
GHS分类：特定目标器官毒性，单次暴露，呼吸道刺激，类别3
H335-可能引起呼吸道刺激

【关于每周分子】

自2001年以来，“每周分子”已成为广受欢迎的栏目。多数分子由读者推荐。每个结构都经由科学家审查，并以3-D和平面图像的形式显示，同时附有该分子简介。可以通过美国化学文摘社 (CAS) 提供的SciFinder中的CAS REGISTRY获取“每周分子”的更多信息。CAS REGISTRY中的每条物质信息都展示了物质的CAS登记号、索引名、通用名、商品名、书目信息等其他更多信息。发送邮件至motw@acs.org推荐您感兴趣的分子吧。

Cesium dodecaborate is one of many known salts of polyborane anions. The dodecaborate anion has the shape of a regular octahedron, one of the five platonic solids. Dodecaborate is isoelectronic with dodecahedrane, the Molecule of the Week for February 22, 2021.

In 1960, Anthony R. Pitochelli and M. Frederick Hawthorne at Rohm and Haas’s Redstone Arsenal Research Division (Huntsville, AL) prepared small amounts of some dodecaborate salts. The salts contained trimethylammonium, potassium, and triphenylmethylphosphonium cations.

Later in the decade, Henry C. Miller and Earl L. Muetterties at Du Pont (Wilmington, DE), developed a synthesis of the cesium salt. As described in the 1967 book Borane Anions, the synthesis begins with the reaction of sodium borohydride (NaBH₄) with boron trifluoride (BF₃) to produce the triborate NaB₃H₈. The triborate is then pyrolyzed to give a mixture that includes sodium dodecaborate. The desired anion is obtained by precipitating it as the cesium salt.

Thomas Schlied and co-workers at the University of Stuttgart (Germany) published the crystal structure of cesium dodecaborate in 2000. The crystals are colorless, face-rich cubic with B–B distances of 178 pm and B–H distances of 112 pm. Each cesium ion is in contact with 12 hydrogen atoms, each at a distance of 313 pm.

In recent years, scientists have been exploring practical applications of dodecaborate salts, such as in battery electrodes, catalysis, and sensors. In particular, a research team led by Haibo Zhang and Xiaohai Zhou at the University of Wuhan (China) have used cesium dodecaborate to prepare complex catalysts.

In 2018, the researchers reported the preparation of a class of core–shell magnetic gold nanocomposites with “raspberry-like” structures. Cesium dodecaborate played a dual role in preparing highly monodispersed gold nanoparticles (AuNPs) and immobilizing them on the surface of a γCD@Fe₃O₄ substrate. The resulting AuNPs@Fe₃O₄ composites made highly active and recyclable catalysts for the selective reduction of nitroaromatic compounds to the corresponding anilines.

Two years later, the group showed that cubic platinum nanoparticles capped with cesium dodecaborate catalyzes the direct oxidation of methane by hydrogen peroxide and oxygen to ethanol under mild (50 °C) conditions. The optimized reaction gave >97% conversion to ethanol.

Cesium dodecaboratefast facts

CAS Reg. No.	12008-75-2
SciFinder nomenclature	Dodecaborate(2–), dodecahydro-, cesium (1:2)
Empirical formula	B₁₂Cs₂H₁₂
Molar mass	407.64 g/mol
Appearance	White crystals or powder
Melting point	>650 ºC
Water solubility	Slight

Cesium dodecaborate hazard information

Flammable solids category 1
H228-Flammable solid
Skin corrosion/irritation, category 2
H315-Causes skin irritation
Serious eye damage/eye irritation, category 2A
H319-Causes serious eye irritation
Specific target organ toxicity, single exposure, respiratory tract irritation, category 3
H335-May cause respiratory irritation

About Molecule of the Week

MOTW has been a popular feature on ACS website since 2001. Many molecules are suggested by our website visitors. Every structure is reviewed by a scientist and displayed in 3-D and flat images with a brief description. Each week’s molecule also links to a sample record from the CAS REGISTRY, which is searched using SciFinder. Each record displays the registry number, index name and synonyms, bibliographic information, and more. Send us a molecule suggestion at motw@acs.org.

往期回顾：

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