Octadecaborane

Octadecaborane(22)

Names
Other names octadecaborane; octadecaboron doicosahydride; octodecaborane; n-Octadecaborane; i-Octadecaborane
Identifiers
CAS Number	21107-56-2 Y
ECHA InfoCard	100.224.871
EC Number	695-976-3
Properties
Chemical formula	B18H22
Molar mass	216.77 g/mol
Appearance	White to off white powder
Density	1.012 g/cm3
Melting point	180 and 129 °C (356 and 264 °F; 453 and 402 K) n-B18H22 and i-B18H22 respectively
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Octadecaborane is an inorganic compound, a boron hydride cluster with chemical formula B₁₈H₂₂. 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.

It is formed by oxidative degradation of B₂₀H₁₈²⁻ or by oxidative coupling of B₉H₁₂⁻.

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 B₉H₁₁ polyhedral subunits, each having a decaborane-like form, joined at a B–B edge.^[1][2] 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.^[3] There are two different geometric isomers of this compound, differing in the orientation of the two edge-fused polyhedra to each other.^[1][2] This compound was the first borane found to have multiple isomeric forms.^[4] Among the geometric isomers, one with chirality was the first borane to be resolved into its separate enantiomers, and was only the second chiral borane known at that time.^[5]