Titanium tetrabromide

Titanium tetrabromide

Titanium tetrabromide
Ball-and-stick model of the titanium tetrabromide molecule
Names
IUPAC name Titanium tetrabromide
Other names Titanium(IV) bromide
Identifiers
CAS Number	7789-68-6 Y
EC Number	232-185-0
Jmol 3D model	Interactive image
PubChem	123263
InChI InChI=1S/4BrH.Ti/h4*1H;/q;;;;+4/p-4
SMILES [Ti](Br)(Br)(Br)Br
Properties
Chemical formula	TiBr4
Molar mass	367.483 g/mol
Appearance	brown crystals hygroscopic
Density	3.25 g/cm3
Melting point	39 °C (102 °F; 312 K)
Boiling point	230 °C (446 °F; 503 K)
Solubility in water	decomposition
Solubility in other solvents	chlorocarbons, benzene
Structure
Crystal structure	cubic, Pa3, Z = 8
Coordination geometry	Tetrahedral
Dipole moment	0 D
Vapor pressure	{{{value}}}
Related compounds
Other anions	TiCl4 TiI4
Other cations	VCl4
Related compounds	TiCl3 VBr3
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Titanium tetrabromide is the chemical compound with the formula TiBr₄. It is the most volatile transition metal bromide. The properties of TiBr₄ are an average of TiCl₄ and TiI₄. Some key properties of these four-coordinated Ti(IV) species are their high Lewis acidity and their high solubility in nonpolar organic solvents. TiBr₄ is diamagnetic, reflecting the d⁰ 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 TiO₂ with carbon and bromine (see Kroll process), and (iii) by treatment of TiCl₄ with HBr.

Reactions

Titanium tetrabromide forms adducts such as TiBr₄(THF)₂ and [TiBr₅]⁻. With bulky donor ligands, such as 2-methylpyridine (2-Mepy), five-coordinated adducts form. TiBr₄(2-MePy) is trigonal bipyramidal with the pyridine in the equatorial plane.

TiBr₄ has been used as a Lewis-acid catalyst in organic synthesis.

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 is uncertain. One proposed pathway invokes the intermediacy of dimers.

Safety

TiBr₄ hydrolyzes rapidly, potentially dangerously, to release hydrogen bromide.