Properties
The compound crystallizes as a yellow-orange hygroscopic needles. It is soluble not only in water, but also in many oxygen-containing solvents, such as alcohols, esters, ethers, and ketones. For example, in dry dibutyl ether of diethylene glycol, the solubility exceeds 1 mol/L. Saturated solutions in the organic solvents often are the liquid solvates of specific stoichiometry.
When heated in air of solid HAuCl4•n H2O, it melts in the water of crystallization, quickly darkens and becomes dark brown. Heating of HAuCl4•n H2O in a stream of chlorine gives gold(III) chloride (Au2Cl6)
The AuCl4- anion has square planar molecular geometry. The Au-Cl distances are around 2.28 Å. Other d8 complexes adopt similar structrures, e.g. tetrachloroplatinate.
As a strong acid, HAuCl4 converts to the alkali metal salts MAuCl4 (M = Li, Na, K, etc.), which are soluble. The related thallium salt is poorly soluble in all nonreacting solvents. Salts of quaternary ammonium cations are known. Other complex salts include and Cl2.
Chloroauric acid is reduced by many substances to give gold(I) or gold(0). This redox is used in many syntheses of gold(I) complexes, especially with organic ligands. Often the ligand serves as reducing agent as illustrated with thiourea:
- AuCl4- + 4 (H3N)2CS → Au((H3N)2CS)2+ + (NH2(NH)CS)22+ + 4 Cl-
Read more about this topic: Chloroauric Acid
Famous quotes containing the word properties:
“The reason why men enter into society, is the preservation of their property; and the end why they choose and authorize a legislative, is, that there may be laws made, and rules set, as guards and fences to the properties of all the members of the society: to limit the power, and moderate the dominion, of every part and member of the society.”
—John Locke (1632–1704)
“A drop of water has the properties of the sea, but cannot exhibit a storm. There is beauty of a concert, as well as of a flute; strength of a host, as well as of a hero.”
—Ralph Waldo Emerson (1803–1882)