Contents

Gold(I) bromide

Gold(I) bromide

Names
IUPAC name gold(I) bromide
Other names Aurous bromide Gold monobromide Gold(I) bromide
Identifiers
CAS Number	10294-27-6 Y
3D model (JSmol)	Interactive image
ChemSpider	30968
EC Number	260-763-2
PubChem CID	33567
CompTox Dashboard (EPA)	DTXSID40275053
SMILES Br[Au]
Properties
Chemical formula	AuBr
Molar mass	276.87 g/mol
Appearance	lemon yellow crystals (AuBr-I), yellow-brown (AuBr-P)
Density	7.9 g/cm3
Melting point	165 °C (329 °F; 438 K) (decomposes)
Magnetic susceptibility (χ)	−61.0·10−6cm3/mol
Hazards
NFPA 704 (fire diamond)	3
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Chemical compound

Gold(I) bromide can be formed by synthesis from the elements or partial decomposition of gold(III) bromide by careful control of temperatures and pressures.

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 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.^[1] Small amounts of aluminium, gallium, 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)^[2] have tried to shed light on the question why gold halides form rather different, low symmetry structures rather than the cubic zinc blendorrock 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.

• Gold bromide on webelements