My watch list
my.chemeurope.com  
Login  

Titanium tetrabromide



Titanium tetrabromide
General
Systematic name Titanium tetrabromide
Other names Titanium(IV) bromide
Molecular formula TiBr4
Molar mass 367.48 g/mol
Appearance brown crystals, hygroscopic
CAS number [7789-68-6]
Properties
Density and phase 3.25 g/mL at 25 °C, solid
Solubility in water decomposition
Other solvents chlorocarbons, benzene
Melting point 38-40 °C
Boiling point 230 °C
Structure
Crystal structure cubic, Pa3, Z = 8
Coordination
geometry
Tetrahedral
Dipole moment 0 D
Hazards
MSDS External MSDS
Main hazards corrosive
NFPA 704
Flash point nonflammable
R/S statement R: 14-34
S: 26-36/37/39-45
RTECS number  ?
Supplementary data page
Structure and
properties
n, εr, etc.
Thermodynamic
data
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
Related compounds
Other anions TiCl4
TiI4
Other cations VCl4
Related compounds TiCl3
VBr3
Except where noted otherwise, data are given for
materials in their standard state (at 25 °C, 100 kPa)
Infobox disclaimer and 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.[1]

Contents

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

TiBr4 forms adducts such as TiBr4(THF)2 and [TiBr5]-.[2] 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.[3]

TiBr4 has been used as a Lewis-acid catalyst in organic synthesis.[4]

TiBr4 reacts rapidly with TiCl4 to give a statistical mixture of the tetrahalides, TiBr4-xClx (x = 0-4). The mechanism of this exchange is a matter of some dispute; a reasonable pathway involves the intermediacy of dimers.[5]

Safety

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

References

  1. ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
  2. ^ Colin S. Creaser and J. Alan Creighton (1975). "Pentachloro- and pentabromo-titanate(IV) ions". J. Chem. Soc., Dalton Trans.: 1402 - 1405. doi:10.1039/DT9750001402.
  3. ^ Hensen, K.; Lemke, A.; Bolte, M. (2000). "Tetrabromo(2-methylpyridine-N)-titanate(IV)". Acta Crystallographica C56: e565 - e566. doi:10.1107/S0108270100015407.
  4. ^ B. Patterson, S. Marumoto and S. D. Rychnovsky (2003). "Titanium(IV)-Promoted Mukaiyama Aldol-Prins Cyclizations". Org. Lett. 5 (17): 3163-3166. doi:10.1021/ol035303n.
  5. ^ S. P. Webb and 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.
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Titanium_tetrabromide". A list of authors is available in Wikipedia.
Your browser is not current. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE