Йодид золота (AuI3)

Identification

Gold iodide (AuI3, Gold iodide) is an inorganic salt of gold(III) with iodine. Formula AuI3, CAS 13453-24-2. Synonyms: gold iodide (AuI3), gold triiodide. EC number 236-624-7.

Physico-chemical characteristics

• Molecular Weight: 577.68
• Exact weight: 577.68
• EU number: 236-624-7
• PSA Features: 0
• XLogP3: -8.9905
• Appearance: dark green solid
• Water solubility: insoluble in cold water, decomposes in hot water
• Steam pressure: 13.8 mm Hg. Art. at 25 °C

Substance class and application

AuI3 is the least stable of the gold(III) trihalide salts, prone to thermal decomposition to release iodine and form the more stable gold(I) iodide - which is why the substance decomposes in hot water rather than simply dissolving. Like other gold trihalides, it is used in laboratory practice as a source of gold(III) for coordination synthesis and as a reagent for comparative studies of the stability of gold halide complexes in the chloride–bromide–iodide series, where the stability of the compounds naturally decreases from chloride to iodide as the covalency of the metal-halogen bond increases. The dark green color of the solid is typical of gold(III) coordination compounds with heavy halide ions and distinguishes it from the yellow and orange-brown gold(III) chloride and bromide, respectively.

Safety Information

• Transport codes: 3260
• Hazard class code: 34-41
• Safety instructions: 26-36/37/39

Hazard class code 34 indicates corrosive properties (causes burns), code 41 indicates risk of serious eye damage; detailed H- and P-phrases according to the GHS system, as well as data on density, melting and boiling points, RTECS number and hazard labels are not provided in the dump.

Storage and transportation

Transport under UN code 3260 - in the same group as other corrosive gold salts. Taking into account thermal instability, the substance should be stored in a dry, cool and dark place, in sealed containers, avoiding heat and contact with moisture, which cause decomposition with the release of iodine. The decomposition of AuI3 is accompanied by the release of elemental iodine, which must be taken into account when choosing container materials and ventilation of the storage location.

Comparison with other gold(III) salts

Among gold(III) trihalides, it is iodide that demonstrates the least stability: while chloride is stable up to melting at 102–103 °C, and bromide decomposes when heated to about 160 °C, then triiodide is prone to decomposition even at room conditions in the presence of moisture. This pattern illustrates a principle common to coordination chemistry: with increasing radius and polarizability of the halide ion, the thermal stability of the corresponding gold(III) compound decreases. In practice, this means that when synthesizing gold(III) coordination complexes based on AuI3, the work must be carried out taking into account the limited stability time of the reagent and as quickly as possible.