Titanium tetrabromide
| Titanium tetrabromide | ||
|---|---|---|
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| IUPAC name Titanium tetrabromide | ||
| Other names Titanium(IV) bromide | ||
| Identifiers | ||
| CAS number | 7789-68-6  | |
| PubChem | 123263 | |
| EC number | 232-185-0 | |
| Jmol-3D images | {{#if:[Ti](Br)(Br)(Br)Br|Image 1 | |
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| Properties | ||
| Molecular 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 | |
| Hazards | ||
| R-phrases | 14-34 | |
| S-phrases | 26-36/37/39-45 | |
| Main hazards | corrosive | |
| NFPA 704 |
 0
3
1
| |
| Flash point | Non-flammable | |
| Related compounds | ||
| Other anions | TiCl4 TiI4 | |
| Other cations | VCl4 | |
| Related compounds | TiCl3 VBr3 | |
(verify) (what is: / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa) | ||
| 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.[1]
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]-.[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]
The tetrabromide and tetrachlorides of titanium react to give a statistical mixture of the mixed tetrahalides, TiBr4-xClx (x = 0-4). The mechanism of this redistribution reaction is uncertain. One proposed pathway invokes the intermediacy of dimers.[5]
Safety
TiBr4 hydrolyzes rapidly, potentially dangerously, to release hydrogen bromide.
References
- ↑ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
- ↑ Colin S. Creaser and J. Alan Creighton (1975). "Pentachloro- and pentabromo-titanate(IV) ions". J. Chem. Soc., Dalton Trans. (14): 1402–1405. doi:10.1039/DT9750001402.
- ↑ Hensen, K.; Lemke, A.; Bolte, M. (2000). "Tetrabromo(2-methylpyridine-N)-titanate(IV)". Acta Crystallographica C56 (12): e565 – e566. doi:10.1107/S0108270100015407.
- ↑ 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. PMID 12917007.
- ↑ 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.
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