Tantalum(V) bromide

Tantalum(V) bromide
Names
	Other names tantalum pentabromide
Identifiers
CAS Number	13451-11-1 TaBr5 ; 17786-61-7 Ta2Br10 ;
3D model (JSmol)	Interactive image;
ECHA InfoCard	100.033.276
EC Number	236-618-4;
PubChem CID	83480;
CompTox Dashboard (EPA)	DTXSID1065471 ;
	InChI InChI=1S/5BrH.Ta/h5*1H;/q;;;;;+5/p-5;
	SMILES Br[Ta](Br)(Br)(Br)Br;
Properties
Chemical formula	Ta2Br10
Molar mass	580.468 g/mol
Appearance	yellow solid
Density	4.99 g/cm³, solid
Melting point	265 °C (509 °F; 538 K)
Boiling point	349 °C (660 °F; 622 K)
Solubility in water	hydrolysis
Hazards
EU classification (DSD) (outdated)	not listed
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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	Infobox references

Tantalum(V) bromide is the inorganic compound with the formula Taa₂Br₁₀. Its name comes from the compound's empirical formula, TaBr₅.[1] It is a diamagnetic, orange solid that hydrolyses readily. The compound adopts an edge-shared bioctahedral structure, which means that two TaBr₅ units are joined by a pair of bromide bridges. There is no bond between the Ta centres.[2] Niobium(V) chloride, niobium(V) bromide, niobium(V) iodide, tantalum(V) chloride, and tantalum(V) iodide all share this structural motif.

Preparation and handling

The material is usually prepared by the reaction of bromine with tantalum metal (or tantalum carbide) at elevated temperatures in a tube furnace. The bromides of the early metals are sometimes preferred to the chlorides because of the relative ease of handling liquid bromine vs gaseous chlorine. Like other molecular halides, it is soluble in nonpolar solvents such as carbon tetrachloride (1.465 g/100 mL at 30 °C), but it reacts with some solvents.[3]

It can also be produced from the more accessible oxide by metathesis using aluminium tribromide:

Ta₂O₅ + 3.3 AlBr₃ → 2 TaBr₅ + 3.3 Al₂O₃

Carbothermal reduction of the oxide in the presence of bromine has also been employed, the byproduct being COBr₂.[4]

References

Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.
Habermehl, Katja; Pantenburg, Ingo; Meyer, Gerd (2010). "Redetermination of tantalum pentabromide, (TaBr5)2". Acta Crystallographica Section E. 66 (9): i67. doi:10.1107/S1600536810032538. PMC 3007875. PMID 21588474.
Nowicki, D. H.; Campbell, I. E. (1953). "Tantalum(V) Bromide". Inorganic Syntheses. 4: 130. doi:10.1002/9780470132357.ch44.
G. Braurer (1963). "Niobium(V) and Tantalum(V) Bromides". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. 1. NY, NY: Academic Press. p. 1311.

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[1] Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.

[2] Habermehl, Katja; Pantenburg, Ingo; Meyer, Gerd (2010). "Redetermination of tantalum pentabromide, (TaBr5)2". Acta Crystallographica Section E. 66 (9): i67. doi:10.1107/S1600536810032538. PMC 3007875. PMID 21588474.

[3] Nowicki, D. H.; Campbell, I. E. (1953). "Tantalum(V) Bromide". Inorganic Syntheses. 4: 130. doi:10.1002/9780470132357.ch44.

[4] G. Braurer (1963). "Niobium(V) and Tantalum(V) Bromides". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. 1. NY, NY: Academic Press. p. 1311.