Titanium tetrabromide
{{chembox
| Watchedfields = changed
| verifiedrevid = 428093946
| Name = Titanium tetrabromide
| ImageFile = TiBr4.png
| ImageName = Titanium tetrabromide
| ImageFile1 = Titanium-tetrabromide-3D-balls.png
| ImageName1 = Ball-and-stick model of the titanium tetrabromide molecule
| IUPACName = Titanium(IV) bromide
| OtherNames = Titanium tetrabromide
|Section1={{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|??}}
| CASNo = 7789-68-6
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 1CBW950X1W
| PubChem = 123263
| RTECS =
| EINECS = 232-185-0
| StdInChI = 1S/4BrH.Ti/h4*1H;/q;;;;+4/p-4
| StdInChIKey = UBZYKBZMAMTNKW-UHFFFAOYSA-J
| SMILES = [Ti](Br)(Br)(Br)Br
}}
|Section2={{Chembox Properties
| Formula = TiBr4
| MolarMass = 367.483 g/mol
| Appearance = brown crystals
hygroscopic
| Density = 3.25 g/cm3
| Solubility = hydrolyses
| Solvent = other solvents
| SolubleOther = chlorocarbons, benzene
| MeltingPtC = 39
| BoilingPtC = 230
}}
|Section3={{Chembox Structure
| Coordination = Tetrahedral
| CrystalStruct = cubic, Pa3, Z = 8
| Dipole = 0 D
}}
|Section7={{Chembox Hazards
| ExternalSDS =
| MainHazards = corrosive
| NFPA-H = 3
| NFPA-F = 0
| NFPA-R = 1
| NFPA-S =
| FlashPt = Non-flammable
| GHSPictograms = {{GHS05}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|314}}
| PPhrases = {{P-phrases|260|264|280|301+330+331|303+361+353|304+340|305+351+338|310|363|405}}
}}
|Section8={{Chembox Related
| OtherAnions = Titanium(IV) chloride
Titanium(IV) fluoride
Titanium(IV) iodide
| OtherCompounds = Titanium(III) bromide
}}
}}
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.Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. {{ISBN|0-12-352651-5}}.
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]−.{{cite journal | journal = J. Chem. Soc., Dalton Trans. | year = 1975 | issue = 14 | pages = 1402–1405 | doi = 10.1039/DT9750001402 | title =Pentachloro- and pentabromo-titanate(IV) ions |author1=Colin S. Creaser |author2=J. Alan Creighton |name-list-style=amp }} 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.{{cite journal |author1=Hensen, K. |author2=Lemke, A. |author3=Bolte, M. | title = Tetrabromo(2-methylpyridine-N)-titanate(IV) | journal = Acta Crystallographica | year = 2000 | volume = C56 | issue = 12 | pages = e565–e566 | doi = 10.1107/S0108270100015407|bibcode=2000AcCrC..56E.565H }}
TiBr4 has been used as a Lewis-acid catalyst in organic synthesis.{{cite journal |author1=B. Patterson, S. Marumoto |author2=S. D. Rychnovsky |name-list-style=amp | title = Titanium(IV)-Promoted Mukaiyama Aldol-Prins Cyclizations | year = 2003 | journal = Org. Lett. | volume = 5 | issue = 17 | pages = 3163–3166 | doi = 10.1021/ol035303n | pmid = 12917007}}
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.{{cite journal |author1=S. P. Webb |author2=M. S. Gordon |name-list-style=amp | title = Intermolecular Self-Interactions of the Titanium Tetrahalides TiX4 (X = F, Cl, Br) | year = 1999 | journal = J. Am. Chem. Soc. | volume = 121 | issue = 11 | pages = 2552–2560 | doi = 10.1021/ja983339i| url = https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1355&context=chem_pubs }}
Safety
TiBr4 hydrolyzes rapidly, potentially dangerously, to release hydrogen bromide, otherwise known as hydrobromic acid.
References
{{reflist}}
{{Titanium compounds}}
{{bromides}}