Zirconium(III) bromide

Zirconium(III) bromide
Names
	IUPAC name Zirconium tribromide
Identifiers
CAS Number	24621-18-9 ;
3D model (JSmol)	Interactive image;
ChemSpider	8185694;
PubChem CID	10010115;
	InChI InChI=1S/3BrH.Zr/h3*1H;/q;;;+3/p-3 Key: YRDBVAQLYFVSFE-UHFFFAOYSA-K;
	SMILES Br[Zr](Br)Br;
Properties
Chemical formula	Br3Zr
Molar mass	330.936 g·mol−1
Appearance	black
Structure
Crystal structure	Hexagonal
Space group	P63/mcm, No. 193
Lattice constant	a = 6.728 Å, c = 6.299 Å α = 90°, β = 90°, γ = 120°
Related compounds
Other anions	Zirconium(III) chloride; Zirconium(III) iodide
Other cations	Titanium(III) bromide; Hafnium(III) bromide
Related compounds	Zirconium(IV) bromide
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Zirconium(III) bromide is an inorganic compound with the formula ZrBr₃.

Preparation[edit]

Almost all the trihalides of titanium, zirconium and hafnium can be prepared by the high-temperature reduction of the corresponding tetrahalide with the metal. Incomplete reaction and contamination of the product with excess metal often occurs.^[1]

Zirconium(III) bromide can thus be prepared from zirconium(IV) bromide and zirconium foil.

3 ZrBr₄ + Zr → 4 ZrBr₃

Alternatively, zirconium(III) bromide crystallises from a solution of zirconium(III) in aluminium tribromide. The solution is prepared by reducing a eutectic solution of ZrBr₄ in liquid AlBr₃ at a temperature of 230–300 °C with metallic zirconium or aluminium.^[2]^[3]

Structure and bonding[edit]

Zirconium(III) bromide has a lower magnetic moment than is expected for the d¹ metal ion Zr³⁺, indicating non-negligible Zr-Zr bonding.^[1]

The crystal structure of zirconium(III) bromide is based on hexagonal close packing of bromide ions with one third of the octahedral interstices occupied by Zr³⁺ ions.^[1] The structure consists of parallel chains of face-sharing {ZrBr₆} octahedra with equally spaced metal atoms. There is some elongation of the octahedra along the metal-metal axis, partly due to metal-metal repulsion.^[3] ZrCl₃, ZrBr₃ and ZrI₃ all adopt the β-TiCl₃ structure,^[1] but the elongation of octahedra is most pronounced in the chloride, moderate in the bromide and negligible in the iodide.^[3]

References[edit]

^ ^a ^b ^c ^d Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 965. ISBN 978-0-08-037941-8.
^ Larsen, E. M.; Moyer, James W.; Gil-Arnao, Francisco; Camp, Michael J. (1974). "Synthesis of crystalline zirconium trihalides by reduction of tetrahalides in molten aluminum halides. Nonreduction of hafnium". Inorg. Chem. 13 (3): 574–581. doi:10.1021/ic50133a015.
^ ^a ^b ^c Larsen, Edwin M.; Wrazel, Julie S.; Hoard, Laurence G. (1982). "Single-crystal structures of ZrX₃ (X = Cl⁻, Br⁻, I⁻) and ZrI_3.40 synthesized in low-temperature aluminum halide melts". Inorg. Chem. 21 (7): 2619–2624. doi:10.1021/ic00137a018.

[G&E-1] Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 965. ISBN 978-0-08-037941-8.

[Larsen74-2] Larsen, E. M.; Moyer, James W.; Gil-Arnao, Francisco; Camp, Michael J. (1974). "Synthesis of crystalline zirconium trihalides by reduction of tetrahalides in molten aluminum halides. Nonreduction of hafnium". Inorg. Chem. 13 (3): 574–581. doi:10.1021/ic50133a015.

[Larsen82-3] Larsen, Edwin M.; Wrazel, Julie S.; Hoard, Laurence G. (1982). "Single-crystal structures of ZrX₃ (X = Cl⁻, Br⁻, I⁻) and ZrI_3.40 synthesized in low-temperature aluminum halide melts". Inorg. Chem. 21 (7): 2619–2624. doi:10.1021/ic00137a018.

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