Chlor-ruthenites

Double salts of ruthenium trichloride and the chlorides of the alkali metals have been prepared and are known as chlor-ruthenites or ruthenochlorides, their general formula being RuCl3.2MC1 or M2RuC16. The first of these to be discovered was ... 

Potassium Chlor-ruthenite, K2RuC15.—This salt may be prepared by the reduction of ruthenium nitrosotrihydroxide, Ru(NO)(OH)3, in alkaline solution by boiling with formaldehyde, dissolving in hydrochloric acid, and separating out the salt by addition of potassium chloride.4 Obtained in this way the crystals are brown in colour. 

The salt may be prepared in an impure form by dissolving ruthenium in fused potassium hydroxide, adding small quantities of potassium nitrate the while, until all the ruthenium has passed into solution. On cooling the green mass becomes orange, and treatment with concentrated hydrochloric leaves a residue of potassium chlor-ruthenite.8... 

A convenient method of preparing a fairly pure specimen of potassium chlor-ruthenite consists in adding freshly distilled ruthenium tetroxide to concentrated hydrochloric acid and digesting on the water-bath until evolution of chlorine ceases. This requires about two days. 

To the resulting strongly acid solution of ruthenium trichloride, potassium chloride is added in small quantities at a time, whereby a precipitate of crystals of potassium chlor-ruthenite is obtained. These are washed free from acid with alcohol, and dried by exposure over concentrated sulphuric acid.1... 

Potassium chlor-ruthenite rapidly hydrolyses in aqueous solution, the liquid, originally red. gradually becoming black. The velocity of the hydrolysis admits of determination by electric conductivity measurements in consequence of the hydrochloric acid set free.2... 

Of particular interest is Caesium Chlor-ruthenite, Cs,.RuC]6.H20, which Howe4 obtained by the action of hydrochloric acid on ruthenium tetroxide and subsequent addition of caesium chloride to the solution. The salt is precipitated as a dark brown powder, fairly soluble in water and hydrochloric acid, exhibiting the chemical reactions of a trivalent ruthenium salt. Howe also describes an isomeride of this salt, which lie termed, in accordance with Werner s nomenclature, Caesium Aquo-chlor-ruthenate [vide infra). 

Potassium Aquo-chlor-ruthenate, K2Ru(OH2)CI5, results1 on boiling a slightly acidified solution of potassium chlor-ruthenite, K2RuC15, with alcohol as also by heating the hydrated sesquioxide with hydrochloric acid and alcohol. 

Caesium Aquo-chlor-ruthenate, Cs2Ru(OH2)Cl3, is an interesting salt inasmuch as it is isomeric with the first chlor-ruthenite to be discovered, namely, Cs2RuCl5. HaO vide supra). It is obtained 3 as a buff precipitate on adding alcohol to the blue filtrate from electrically reduced solutions of ruthenium trichloride and caesium chloride. On crystallisation, rose-coloured prisms are obtained. These are soluble in water, and may be recrystallised unchanged from aqueous hydrochloric acid. 

Ruthenium hydroxide, is obtained in colloidal form by reducing an aqueous solution of potassium chlor-ruthenite, K2RuC15, by hydrazine sulphate in the presence of gum acacia, which serves as a protective colloid, preventing the coagulation of the hydroxide.6... 

When dissolved in potassium hydroxide solution and reduced with formaldehyde, a mixture of hydrates is obtained.4 Addition of hydrochloric acid and potassium chloride and subsequent evaporation results in brown crystals of potassium chlor-ruthenite, KaRuCls, and red crystals of Ru2(NO)CT.3KC1.4-HC1 separating out. These differ in solubility, the former being more rapidly dissolved by cold water than the latter the isolation of each in a pure state is thus easy. 

Ferrous chloride readily unites with other metallic chlorides to form double salts, a considerable variety of which is known. Those of formula M2FeCl4 recall the chlor-ruthenites, M2RuC14, already discussed.6 The best-known double salts are as follow —... 

All three metals yield dichlorides and trichlorides and, in the case of ruthenium and osmium, series of complex salts are known under the names of rutheno-ehlorides or ehlor-ruthenites, M2RuC15, and osmo-chlorides or chlor-osmites, M30sCle or MCKM20sC15. 

Ruthenium and the Halogens—Chlor-ruthenifces and Chlor-rathenates—Ruthenium and Oxygen—Ruthenites and Ruthenates—Ruthenium and Sulphur— Nitroso Derivatives—Double Nitrites—Ruthenium and Carbon—Rutheno-oyanides—Ruthenium and Silioon. 

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