Platinum chloride silver salts

Many of the synthetic routes parallel those used to prepare alkene complexes c platinum(II). Replacement of chloride ion in PtClJ- by a water soluble alkyne is a frequentl used method (equation 266), 809 812 or the reaction can be assisted by the use of a silver salt t facilitate halide displacement (equation 267).813 With hexafluorobutyne-2 the five-coordinat adduct can be isolated before it converts into the vinyl complex (89 equation 268).814 Alkyne displace alkenes from platinum(ll) complexes. 

When hydrochloric acid solutions of noble metal salts are being tested, the presence of silver salts need not be considered. Gold chloride can be removed by shaking the strong hydrochloric acid solution with ether or ethyl acetate. The gold-free aqueous solution should be taken to dryness to remove the excess hydrochloric acid before the test with / -nitroso-diphenylamine is tried. There is as yet no method for the removal of platinum which is suitable for the spot test technique. Since the identification limit of the platinum reaction with />-nitrosodiphenylamine is 10 y, the palladium test just given is not impaired by small amounts of platinum. 

Ammonia forms a great variety of addition or coordination compounds (qv), also called ammoniates, ia analogy with hydrates. Thus CaCl2 bNH and CuSO TNH are comparable to CaCl2 6H20 and CuSO 4H20, respectively, and, when regarded as coordination compounds, are called ammines and written as complexes, eg, [Cu(NH2)4]S04. The solubiHty ia water of such compounds is often quite different from the solubiHty of the parent salts. For example, silver chloride, AgQ., is almost iasoluble ia water, whereas [Ag(NH2)2]Cl is readily soluble. Thus silver chloride dissolves ia aqueous ammonia. Similar reactions take place with other water iasoluble silver and copper salts. Many ammines can be obtained ia a crystalline form, particularly those of cobalt, chromium, and platinum. 

Elemental composition (anhydrous salt) Pt 47.60%, H 0.49%, Cl 51.90%. The compound may be identified by its physical and chemical properties. Platinum in an aqueous solution of the compound can be analyzed by flame AA or ICP spectroscopy. Also, the compound can be measured by gravimetry following precipitation with ammonium chloride, hydrogen sulfide, or silver nitrate (see Reactions above). 

Dichloro-tetrammino-platinic Chloride, [Pt(NH8)4Cl2]Cl2, is prepared by passing chlorine gas through a solution of tetrammino-platinous chloride till the liquid begins to turn red. From the cold dilute solution the salt crystallises with one molecule of water of crystallisation, whilst from more concentrated solutions the anhydrous salt is deposited. It may also be obtained by the action of ammonia on tetraehloro-dianunino-platinum. It crystallises in pale yellow microscopic oetahedra, is sparingly soluble in water, and only half of the chlorine is precipitated as silver chloride when the aqueous solution is treated with a cold solution of silver nitrate. Sulphuric acid eliminates only two molecules of chlorine.1... 

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