Octahydrotriborate is the

boron hydride Diborane(6), commonly known as diborane, is the chemical compound with the formula . It is a highly toxic, colorless, and pyrophoric gas with a repulsively sweet odor. Given its simple formula, borane is a fundamental boron compound. It has attr ...

anion B₃H₈⁻. It forms a variety of salts that are colorless and air-stable. The

tetrabutylammonium Tetrabutylammonium is a quaternary ammonium cation with the formula , also denoted (where Bu = butyl group). It is used in the research laboratory to prepare lipophilic salts of inorganic anions. Relative to tetraethylammonium derivatives, tetr ...

salt is soluble in organic solvents such as

acetonitrile Acetonitrile, often abbreviated MeCN (methyl cyanide), is the chemical compound with the formula and structure . This colourless liquid is the simplest organic nitrile (hydrogen cyanide is a simpler nitrile, but the cyanide anion is not class ...

and

methylene chloride Dichloromethane (DCM, methylene chloride, or methylene bichloride) is an organochlorine compound with the formula . This colorless, volatile liquid with a chloroform-like, sweet odor is widely used as a solvent. Although it is not miscible with ...

. The anion is an intermediate is the synthesis of various higher boron hydrides, such as

pentaborane(9) Pentaborane(9) is an inorganic compound with the formula . It is one of the most common boron hydride clusters, although it is a highly reactive compound. Because of its high reactivity with oxygen, it was once evaluated as rocket or jet fuel. Lik ...

. B₃H₈⁻ can be viewed as the

conjugate base A conjugate acid, within the Brønsted–Lowry acid–base theory, is a chemical compound formed when an acid gives a proton () to a base—in other words, it is a base with a hydrogen ion added to it, as it loses a hydrogen ion in the reve ...

of triborane B₃H₉.

Preparation

Octahydrotriborate is prepared by partial oxidation of

borohydride Borohydride refers to the anion , which is also called tetrahydroborate or more commonly tetrahydrobiopterin, and its salts. Borohydride or hydroborate is also the term used for compounds containing , where ''n'' is an integer from 0 to 3, for ex ...

with iodine or boron trifluoride: :3BH₄⁻ + I₂ → B₃H₈⁻ + 2H₂ + 2I⁻ :5BH₄⁻ + 4BF₃O(C₂H₅)₂ → 2B₃H₈⁻ + 2H₂ + 4O(C₂H₅)₂ + 3BF₄⁻

Structure and reactions

As shown by

X-ray crystallography X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring th ...

of various salts, B₃H₈⁻ consists of a distorted triangle of three BH₂ vertices. Two edges of the triangle are occupied by bridging hydrides. It is converted to the bromide B₃H₇Br⁻ using HBr (illustrating its hydridic character): :B₃H₈⁻ + HBr → B₃H₇Br⁻ + H₂

Pyrolysis Pyrolysis is a process involving the Bond cleavage, separation of covalent bonds in organic matter by thermal decomposition within an Chemically inert, inert environment without oxygen. Etymology The word ''pyrolysis'' is coined from the Gree ...

of this bromide gives

. :5 B₃H₇Br⁻ → 3 B₅H₉ + 5 Br⁻ + 4 H₂ Also consistent with its basicity, B₃H₈^_ functions as a

bidentate ligand In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's ...

in a variety of

coordination complex A coordination complex is a chemical compound consisting of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of chemical bond, bound molecules or ions, that are in turn known as ' ...

es, e.g. Cr(B₃H₈)₂.{{cite journal , doi=10.1021/ja046906c, title=A New Class of CVD Precursors to Metal Borides: Cr(B₃H₈)₂ and Related Octahydrotriborate Complexes, year=2004, last1=Goedde, first1=Dean M., last2=Girolami, first2=Gregory S., journal=Journal of the American Chemical Society, volume=126, issue=39, pages=12230–12231, pmid=15453732, bibcode=2004JAChS.12612230G

References

Borohydrides