Chromithiocyanates

Chromi-nydroxyd, n. chromic hydroxide, chro-mium(III) hydroxide, -oxyd, n. chromic oxide, chromium(III) oxide, -rhodanwasser-stoffsMure, /. chromithiocyanic acid, thio-cyanatochromic(III) acid, -salz, n. chromic salt, chromium(III) salt, -suifat, n. chromic sulfate, chromium(III) sulfate, -suifocyan-saure, /. chromithiocyanic acid, thiocyana-tochromic(III) acid, -verbindung,/. chromic compound, chromium(III) compound. 

An orange-coloured precipitate of m-dithiocyanato-diethyiene-diamino-chromic thiocyanate, [Cr en2(SCN)2](SCN), is produced on warming an aqueous solution of the salt with potassium thiocyanate, and a sparingly soluble chromithiocyanate, [Cr en2(H402)Br]3[Cr(SCN)6]. 2H20, is precipitated on mixing a freshly prepared aqueous solution of the bromide with potassium chromithiocyanate. It crystallises in violet-red transparent needles which are almost insoluble in water and decompose on exposure to light.2... 

Arsenic carbonate has not been prepared, but arsenic salts of several organic acids, including arsenic cyanide, thiocyanate, acetate and tartrate, are known. Arsenic chromithiocyanate, As[Cr(SCN)g], has also been described.5... 

Ammonium Chromithiocyanate, (NH4)3[Cr(SCN)6].4H20, is formed by dissolving freshly precipitated hydroxide in ammonium-thiocyanate solution, or by reducing ammonium dichromate wth alcohol and sulphuric acid, neutralising the solution with ammonia, adding ammonium thiocyanate, and boiling for a short time. ... 

Sodium Chromithiocyanate, Na3[Cr(SCN)s].12H20, yields crimson-coloured crystals, which over sulphuric acid, or when heated at 105° C., become anhydrous and turn violet. A heptahydrate may be obtained by crystallisation from aqueous alcohol. 

Barium Chromithiocyanate, Ba3[Cr(SCN)s]2.16H20, is soluble in water, and is obtained by the methods employed for the alkali salts. It crystallises in short ruby-red prisms. 

Silver Chromithiocyanate, Ag3[Cr(SCN)e], is obtained as a voluminous reddish-brown precipitate, which when boiled with water turns pink. It is insoluble in ammonia, and is not sensitive to light. 

Lead Chromithiocyanate.—The normal salt has not been obtained. The addition of the potassium salt to a solution of lead acetate gives a... 

Mineral acid solutions of bismuth salts react with potassium chromithio-cyanate K8[Cr(CNS)g] to give insoluble brick-red bismuth chromithiocyanate. 

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