Like many related tetrahalides, it is purified by sublimation.
It can also be prepared by treatment of the borohydride complex with hydrogen bromide:[2]
Zr(BH4)4 + 4HBr → ZrBr4 + 4H2 + 2B2H6
Like related tetrabromides of Ti and Hf, ZrBr4 hydrolyzes readily to give the oxybromide, with release of hydrogen bromide.
Structure
No single crystal X-ray study of ZrBr4 has been described. Some reports suggest that it is isostructural with TiCl4 and TiBr4, featuring tetrahedral metal centers.[3] Other studies indicate a polymeric structure.[4] ZrCl4 is polymeric in the solid state, featuring octahedral Zr centers.[5]
References
^R. C. Young, Hewitt G. Fletcher, "Anhydrous Zirconium Tetrabromide" Inorganic Syntheses, 1939, vol. 1, pp. 49–51. doi:10.1002/9780470132326.ch18
^Calderazzo, Fausto; Pallavicini, Piersandro; Pampaloni, Guido (1990). "Arene derivatives of zirconium(II) and hafnium(II)". Journal of the Chemical Society, Dalton Transactions (6): 1813. doi:10.1039/DT9900001813.
^Berdonosov, S. S.; Lapitskii, A. V. (1963). "Structure of Zr and Hf Tetrabromides". Vestnik Moskovskogo Universiteta, Seriya 2: Khimiya. 18: 42–4. (from abstract): The structure was assumed to be similar to that of SnI4 ... was verified by comparing exptl. and calcd. line intensities, by using Cu K radiation for powder patterns. ... Based on the value of the radius of the I− ion, the lattice parameter and the theoretical sp. gravity of ZrI4 and HfI4 were calcd.
^Carter, J. C.; Smith, J. A. S. (1974). "Nuclear quadrupole resonance in hafnium and zirconium tetrabromide". Journal of the Chemical Society, Chemical Communications (20): 835–6. doi:10.1039/c39740000835.
