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Revision as of 01:47, 2 May 2011 editMaterialscientist (talk | contribs)Edit filter managers, Autopatrolled, Checkusers, Administrators1,993,918 editsm Reverted edits by Ebe123 (talk) to last version by CheMoBot← Previous edit Revision as of 16:03, 8 May 2011 edit undoSmokefoot (talk | contribs)Autopatrolled, Extended confirmed users, Pending changes reviewers, Rollbackers74,350 edits →Reactions: Redistribution (chemistry)Next edit →
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==Reactions== ==Reactions==
TiBr<sub>4</sub> forms adducts such as TiBr<sub>4</sub>(])<sub>2</sub> and <sup>-</sup>.<ref>{{cite journal | journal = ] | year = 1975 | issue = 14 | pages = 1402–1405 | doi = 10.1039/DT9750001402 | title =Pentachloro- and pentabromo-titanate(IV) ions | author = Colin S. Creaser and J. Alan Creighton}}</ref> With bulky donor ligands, such as 2-methylpyridine (2-Mepy), five-coordinated adducts form. TiBr<sub>4</sub>(2-MePy) is trigonal bipyramidal with the pyridine in the equatorial plane.<ref>{{cite journal | author = Hensen, K.; Lemke, A.; Bolte, M. | title = Tetrabromo(2-methylpyridine-N)-titanate(IV) | journal = ] | year = 2000 | volume = C56 | issue = 12 | pages = e565 - e566 | doi = 10.1107/S0108270100015407}}</ref> Titanium tetrabromide forms adducts such as TiBr<sub>4</sub>(])<sub>2</sub> and <sup>-</sup>.<ref>{{cite journal | journal = ] | year = 1975 | issue = 14 | pages = 1402–1405 | doi = 10.1039/DT9750001402 | title =Pentachloro- and pentabromo-titanate(IV) ions | author = Colin S. Creaser and J. Alan Creighton}}</ref> With bulky donor ligands, such as ] (2-Mepy), five-coordinated adducts form. TiBr<sub>4</sub>(2-MePy) is trigonal bipyramidal with the pyridine in the equatorial plane.<ref>{{cite journal | author = Hensen, K.; Lemke, A.; Bolte, M. | title = Tetrabromo(2-methylpyridine-N)-titanate(IV) | journal = ] | year = 2000 | volume = C56 | issue = 12 | pages = e565 - e566 | doi = 10.1107/S0108270100015407}}</ref>


TiBr<sub>4</sub> has been used as a Lewis-acid ] in ].<ref>{{cite journal | author = B. Patterson, S. Marumoto and S. D. Rychnovsky | title = Titanium(IV)-Promoted Mukaiyama Aldol-Prins Cyclizations | year = 2003 | journal = ] | volume = 5 | issue = 17 | pages = 3163–3166 | doi = 10.1021/ol035303n | pmid = 12917007}}</ref> TiBr<sub>4</sub> has been used as a Lewis-acid ] in ].<ref>{{cite journal | author = B. Patterson, S. Marumoto and S. D. Rychnovsky | title = Titanium(IV)-Promoted Mukaiyama Aldol-Prins Cyclizations | year = 2003 | journal = ] | volume = 5 | issue = 17 | pages = 3163–3166 | doi = 10.1021/ol035303n | pmid = 12917007}}</ref>


TiBr<sub>4</sub> reacts rapidly with TiCl<sub>4</sub> to give a statistical mixture of the tetrahalides, TiBr<sub>4-x</sub>Cl<sub>x</sub> (x = 0-4). The mechanism of this exchange is a matter of some dispute; a reasonable pathway involves the intermediacy of ]s.<ref>{{cite journal | author = S. P. Webb and M. S. Gordon | title = Intermolecular Self-Interactions of the Titanium Tetrahalides TiX4 (X = F, Cl, Br) | year = 1999 | journal = ] | volume = 121 | issue = 11 | pages = 2552–2560 | doi = 10.1021/ja983339i}}</ref> The tetrabromide and tetrachlorides of titanium react to give a statistical mixture of the mixed tetrahalides, TiBr<sub>4-x</sub>Cl<sub>x</sub> (x = 0-4). The mechanism of this ] is uncertain. One proposed pathway invokes the intermediacy of ]s.<ref>{{cite journal | author = S. P. Webb and M. S. Gordon | title = Intermolecular Self-Interactions of the Titanium Tetrahalides TiX4 (X = F, Cl, Br) | year = 1999 | journal = ] | volume = 121 | issue = 11 | pages = 2552–2560 | doi = 10.1021/ja983339i}}</ref>


==Safety== ==Safety==

Revision as of 16:03, 8 May 2011

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
ECHA InfoCard 100.029.259 Edit this at Wikidata
PubChem CID
CompTox Dashboard (EPA)
Properties
Chemical formula TiBr4
Molar mass 367.48 g/mol
Appearance brown crystals
hygroscopic
Density 3.25 g/cm
Melting point 39 °C
Boiling point 230 °C
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
Occupational safety and health (OHS/OSH):
Main hazards corrosive
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
3 0 1
Flash point nonflammable
Related compounds
Other anions TiCl4
TiI4
Other cations VCl4
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). checkY verify (what is  ?) Infobox references
Chemical compound

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 d 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 . 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, TiBr4-xClx (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.

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. (14): 1402–1405. doi:10.1039/DT9750001402.
  3. Hensen, K.; Lemke, A.; Bolte, M. (2000). "Tetrabromo(2-methylpyridine-N)-titanate(IV)". Acta Crystallographica. C56 (12): e565–e566. doi:10.1107/S0108270100015407.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  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. PMID 12917007.
  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.
Titanium compounds
Titanium(II)
Organotitanium(II) compounds
Titanium(III)
Organotitanium(III) compounds2
Titanium(IV)
Titanate compounds
Organotitanium(IV) compounds
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