Titanium tetrabromide is the
chemical compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...
with the
formula
In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwe ...
TiBr
4. It is the most volatile transition metal bromide. The properties of TiBr
4 are an average of TiCl
4 and TiI
4. Some key properties of these four-coordinated Ti(IV) species are their high Lewis acidity and their high solubility in nonpolar organic solvents. TiBr
4 is diamagnetic, reflecting the d
0 configuration of the metal centre.
Preparation and structure
This four-coordinated complex adopts a tetrahedral geometry. It can be prepared via several methods: (i) from the elements, (ii) via the reaction of TiO
2 with carbon and bromine (see
Kroll process
The Kroll process is a pyrometallurgical industrial process used to produce metallic titanium from titanium tetrachloride. As of 2001 William Justin Kroll's process replaced the Hunter process for almost all commercial production.
Process
In the ...
), and (iii) by treatment of TiCl
4 with
HBr.
Reactions
Titanium tetrabromide forms adducts such as TiBr
4(
THF)
2 and
iBr5sup>−. With bulky donor ligands, such as
2-methylpyridine (2-Mepy), five-coordinated adducts form. TiBr
4(2-MePy) is trigonal bipyramidal with the pyridine in the equatorial plane.
TiBr
4 has been used as a Lewis-acid
catalyst
Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick ...
in
organic synthesis
Organic synthesis is a branch of chemical synthesis concerned with the construction of organic compounds. Organic compounds are molecules consisting of combinations of covalently-linked hydrogen, carbon, oxygen, and nitrogen atoms. Within the gen ...
.
The tetrabromide and tetrachlorides of titanium react to give a statistical mixture of the mixed tetrahalides, TiBr
4−xCl
x (x = 0-4). The mechanism of this
redistribution reaction
In chemistry, redistribution usually refers to the exchange of anionic ligands bonded to metal and metalloid centers. The conversion does not involve redox
Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical ...
is uncertain. One proposed pathway invokes the intermediacy of
dimers.
Safety
TiBr
4 hydrolyzes rapidly, potentially dangerously, to release
hydrogen bromide
Hydrogen bromide is the inorganic compound with the formula . It is a hydrogen halide consisting of hydrogen and bromine. A colorless gas, it dissolves in water, forming hydrobromic acid, which is saturated at 68.85% HBr by weight at room temper ...
, otherwise known as hydrobromic acid.
References
{{bromides
Bromides
Titanium halides
Titanium(IV) compounds