Boron triiodide can be prepared by the reaction of boron with iodine at 209.5 °C or 409.1 °F.[citation needed]
It can also be prepared by reacting hydroiodic acid with boron trichloride:
In its pure state, boron triiodide forms colorless, otherwise reddish, shiny, air and hydrolysis-sensitive[3] crystals, which have a hexagonal crystal structure (a = 699.09 ± 0.02 pm, c = 736.42 ± 0.03 pm, space groupP63/m (space group no. 176)).[4] Boron triiodide is a strong Lewis acid and soluble in carbon disulfide.[2]
Boron triiodide reacts with water and decomposes to boric acid and hydriodic acid:
BI3 + 3H2O ⇌ B(OH)3 + 3HI
Its dielectric constant is 5.38 and its heat of vaporization is 40.5 kJ/mol. At extremely high pressures, BI3 becomes metallic at ~23 GPa and is a superconductor above ~27 GPa.[5]
Applications
Boron triiodide can be used to produce other chemical compounds and as a catalyst (for example in coal liquefaction).[6]
References
^Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton, Florida: CRC Press. ISBN0-8493-0486-5.