Cesium dodecaborate

August 02, 2021
I鈥檓 mostly boron, but you won鈥檛 find me boring.
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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 Hawthorne1 at Rohm and Haas鈥檚 Redstone Arsenal Research Division (Huntsville, AL) prepared small amounts of some . 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 2, 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 in 2000. The crystals are colorless, face-rich cubic with B鈥揃 distances of 178 pm and B鈥揌 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 . Cesium dodecaborate played a dual role in preparing highly monodispersed gold nanoparticles (AuNPs) and immobilizing them on the surface of a 纬CD@Fe3O4 substrate3. 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 under mild (50 掳C) conditions. The optimized reaction gave >97% conversion to ethanol.

1. Hawthorne, a giant in the field of boron chemistry, at age 92. Nicknamed 鈥淢r. Boron鈥� by his associates, he was awarded the prestigious ACS Priestly Medal in 2009.
2. Hawthorne, Miller, and Muetterties, among others, were coauthors.
3. 纬CD@Fe3O4 is a 纬-cyclodextrin鈥揾ematite complex.


Cesium dodecaborate hazard information

Hazard class*GHS code and hazard statement
Flammable solids, category 1H228鈥擣lammable solidChemical Safety Warning
Skin corrosion/irritation, category 2H315鈥擟auses skin irritationChemical Safety Warning
Serious eye damage/eye irritation, category 2AH319鈥擟auses serious eye irritationChemical Safety Warning
Specific target organ toxicity, single exposure, respiratory tract irritation, category 3H335鈥擬ay cause respiratory irritationChemical Safety Warning

*Globally Harmonized System (GHS) of Classification and Labeling of Chemicals.听

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Cesium dodecaborate
fast facts

CAS Reg. No.12008-75-2

nomenclature
Dodecaborate(2鈥�), dodecahydro-, cesium (1:2)
Empirical formulaB12Cs2H12
Molar mass407.64 g/mol
AppearanceWhite crystals or powder
Melting point>650 掳C
Water solubilitySlight

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