Metals gold salts

Sulfamic acid and its salts retard the precipitation of barium sulfate and prevent precipitation of silver and mercury salts by alkah. It has been suggested that salts of the type AgNHSO K [15293-60 ] form with elemental metals or salts of mercury, gold, and silver (19). Upon heating such solutions, the metal deposits slowly ia mirror form on the wall of a glass container. Studies of chemical and electrochemical behavior of various metals ia sulfamic acid solutions are described ia Reference 20. 

These short Au-Au contacts may be compared with distances of 2.88 A in metallic gold and 2.60 A in gaseous Au2. The term aurophilicity has been coined by H. Schmidbaur to describe the phenomenon [189,194], The interactions can occur as pairs, squares, linear chains or two-dimensional arrays of gold centres. Examples include the association between dimer units in the dithiocarbamates Au(dtc)2 (Figure 4.16) and the ionic tetrahydrothiophen complexes Au(tht)2 AuXJ (X = halogen), where cations and anions stack with Au—Au 2.97-2.98 A (X = I). The interaction is such that Au(S203)2 pair up, despite their charge, with Au-Au 3.24 A in the sodium salt. Likewise in Aupy AuCl, cations pair up at 3.42 A apart [10, 195]. 

It reduces copper, silver and gold salts in solutions, precipitating metal phosphides or the metals themselves ... 

Colloidal solutions of metals can also be prepared, but only from the noble metals, since the others form hydroxides with water. A gold sol can be prepared by treating a weakly alkaline solution of a gold salt, such as KAuC14, with formalin or another reducing agent. 

We find in Albertus a general knowledge of many specific facts and operations of chemistry. He knew of the operations of distillation and sublimation and of the apparatus used in these operations, of the purification of gold and silver by cementation and by the use of lead. He knew that quicksilver may be successively distilled without loss of weight that cinnabar can be produced by the union of quicksilver and sulphur that wine, when heated gives off an inflammable substance which he calls an oil (oleum) supernatant and inflammable. 61 He describes many metals, minerals, salts and other substances, without, however, adding any facts of interest not comprised in the authorities which precede him. 

Selenium reduces hot aqueous solutions of silver or gold salts with the formation of silver selenide or metallic gold, respectively. In the case of silver salts the reaction corresponds with the equation 6... 

The hydration of alkynes is also accomplished by use of catalytic amounts of palladium and gold salts.305 The mildness of this reaction is demonstrated by the preparation of 5-oxo-prostaglandin derivatives (equation 202). In this connection, it should be noted that attempted use of other metal salts to catalyze C—-C triple bond hydrations has met with little success.306... 

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