Titanium tetrabromide

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.^[2]

Titanium tetrabromide

Names
IUPAC name Titanium(IV) bromide
Other names Titanium tetrabromide
Identifiers
CAS Number	7789-68-6 Y
3D model (JSmol)	Interactive image
ECHA InfoCard	100.029.259
EC Number	232-185-0
PubChem CID	123263
UNII	1CBW950X1W Y
CompTox Dashboard (EPA)	DTXSID90894990
InChI InChI=1S/4BrH.Ti/h4*1H;/q;;;;+4/p-4 Key: UBZYKBZMAMTNKW-UHFFFAOYSA-J
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	hydrolyses
Solubility in other solvents	chlorocarbons, benzene
Structure
Crystal structure	cubic, Pa3, Z = 8
Coordination geometry	Tetrahedral
Dipole moment	0 D
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	corrosive
GHS labelling:[1]
Pictograms
Signal word	Danger
Hazard statements	H314
Precautionary statements	P260, P264, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P363, P405
NFPA 704 (fire diamond)	3 0 1
Flash point	Non-flammable
Related compounds
Other anions	Titanium(IV) chloride Titanium(IV) fluoride Titanium(IV) iodide
Related compounds	Titanium(III) bromide
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

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]⁻.^[3] 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.^[4]

TiBr₄ has been used as a Lewis-acid catalyst in organic synthesis.^[5]

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.^[6]

Safety

TiBr₄ hydrolyzes rapidly, potentially dangerously, to release hydrogen bromide, otherwise known as hydrobromic acid.

References

1. "Titanium tetrabromide". pubchem.ncbi.nlm.nih.gov. Retrieved 12 December 2021.
2. Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
3. Colin S. Creaser & J. Alan Creighton (1975). "Pentachloro- and pentabromo-titanate(IV) ions". J. Chem. Soc., Dalton Trans. (14): 1402–1405. doi:10.1039/DT9750001402.
4. Hensen, K.; Lemke, A.; Bolte, M. (2000). "Tetrabromo(2-methylpyridine-N)-titanate(IV)". Acta Crystallographica. C56 (12): e565–e566. Bibcode:2000AcCrC..56E.565H. doi:10.1107/S0108270100015407.
5. B. Patterson, S. Marumoto & S. D. Rychnovsky (2003). "Titanium(IV)-Promoted Mukaiyama Aldol-Prins Cyclizations". Org. Lett. 5 (17): 3163–3166. doi:10.1021/ol035303n. PMID 12917007.
6. S. P. Webb & M. S. Gordon (1999). "Intermolecular Self-Interactions of the Titanium Tetrahalides TiX4 (X = F, Cl, Br)". J. Am. Chem. Soc. 121 (11): 2552–2560. doi:10.1021/ja983339i.