Gold(I) bromide can be formed by synthesis from the elements or partial decomposition of

gold(III) bromide Gold(III) bromide is a dark-red to black crystalline solid.Macintyre, J. E. (ed.) ''Dictionary of Inorganic Compounds''; Chapman & Hall: London, 1992; vol. 1, pp. 121Greenwood, N.N.; Earnshaw, A. ''Chemistry of the Elements''; Butterworth-Heineman ...

by careful control of temperatures and pressures.

Structure

It occurs in two modifications. One (I-AuBr) is isostructural with gold(I) chloride and has a body centered tetragonal unit cell with a = 6.734 Å, c = 8.674 Å, and space group I4₁/amd. The other (P-AuBr) is isostructural with

gold(I) iodide Gold monoiodide is the inorganic compound of gold and iodine with the formula AuI. It can be synthesized by dissolving gold powder in an aqueous solution of iodine and potassium iodide Potassium iodide is a chemical compound, medication, a ...

and has a primitive tetragonal cell a = 4.296 Å, c = 12.146 Å, and space group P4₂/ncm. Single crystals of both modifications have been grown by chemical vapor transport. Small amounts of aluminum,

gallium Gallium is a chemical element with the symbol Ga and atomic number 31. Discovered by French chemist Paul-Émile Lecoq de Boisbaudran in 1875, Gallium is in group 13 of the periodic table and is similar to the other metals of the group (aluminiu ...

, or iron were used as catalysts for the transport process to obtain the I-AuBr modification. The two structures both consist of -Br-Au-Br-Au-Br- polymeric zigzag chains, but they are stacked in a different arrangement. In the primitive tetragonal I-AuBr, the chains form layers (see figure) in contrast to the body centered P-AuBr, where they are more interwoven. Another difference is that the Au-Br-Au angle is only 77° in the former, but 92.3° in the latter. Density functional calculations on the monohalides of group 11 (Cu, Ag, Au) have tried to shed light on the question why gold halides form rather different, low symmetry structures rather than the cubic zinc blend or rock salt structures of the silver and copper halides. It was shown that this calculation technique accurately predicts which structure type should be stable. The peculiar structures of the gold halides are mostly a result of the relativistic effects that occur for the elements of the later periods of the periodic table.

References

External links

Gold bromide on webelements
{{Bromides Bromides Metal halides Gold(I) compounds Gold–halogen compounds