Octadecaborane is an
inorganic compound
In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...
, a
boron hydride cluster with chemical formula B
18H
22. It is a colorless flammable solid, like many higher
boron hydrides. Although the compound has no practical applications, its structure is of theoretical and pedagogical interest.
Synthesis
It is formed by oxidative degradation of B
20H
182− or by
oxidative coupling of B
9H
12−.
Structure
Two isomers are known of octadecaborane, providing the first example of isomers in a boron-hydride cluster. The clusters are also of interest because the boron centers shared between the two subunits have an unusually high number of B-B interactions. The isomers consists of two B
9H
11 polyhedral subunits, each having a
decaborane
Decaborane, also called decaborane(14), is the borane with the chemical formula B10 H14. This white crystalline compound is one of the principal boron hydride clusters, both as a reference structure and as a precursor to other boron hydrides. It ...
-like form, joined at a B–B edge.
These two boron atoms are each coordinated to six others; this compound was the first one found to have such a high number of borons coordinated around a single boron center. There are two different geometric isomers of this compound, differing in the orientation of the two edge-fused polyhedra to each other.
This compound was the first borane found to have multiple isomeric forms. Among the geometric isomers, one with
chirality
Chirality is a property of asymmetry important in several branches of science. The word ''chirality'' is derived from the Greek (''kheir''), "hand", a familiar chiral object.
An object or a system is ''chiral'' if it is distinguishable from ...
was the first borane to be
resolved into its separate
enantiomer
In chemistry, an enantiomer ( /ɪˈnænti.əmər, ɛ-, -oʊ-/ ''ih-NAN-tee-ə-mər''; from Ancient Greek ἐνάντιος ''(enántios)'' 'opposite', and μέρος ''(méros)'' 'part') – also called optical isomer, antipode, or optical ant ...
s, and was only the second chiral borane known at that time.
References
{{Hydrides by group
Boranes