Chloro-pentammino-chromic chloride, preparation

References Christensen, Z. anorg. Chem., 4, 229 (1893) to prepare chloro-pentammino-chromic chloride without the use of liquid ammonia, Christensen, J. prakt. Chem., (2) 23, 54 (1881) Jorgensen, J. prakt. Chem., (2) 20, 105 (1879). 

Nitro-pentammino-chromic Chloride, [Cr(NH8)5X02]Cl2, is prepared from ehloro-pentammino-chromic chloride by heating it for a short time with water acidified with nitric acid, allowing the mixture to cool slowly, and filtering off the undissolved ehloro-pentammino-salt. The filtrate, which contains aquo-pentammino-ehromic salt, is decomposed with sodium nitrite and a 12 per cent, solution of hydrochloric acid after a few minutes the precipitate formed is collected, washed with water, dissolved in water, and filtered into a strong solution of ammonium chloride. The precipitated crystals are collected, washed with water and alcohol, and obtained as yellow octahedral prisms.-The salt, which is soluble in water, decomposes on heating with hydrochloric acid, giving chloro-pentammino-salt.3... 

Chloro-pentammino-chromic Bromide, [Cr(NH3)5Cl]Bra, has similar properties, and is prepared by addition of concentrated hydro-bromic acid to a cold aqueous solution of the chloride. 

Chloro-pentammino-chromic Sulphate, [Cr(N I3)5Cl]S04.2H20, is prepared by treating the chloride with silver carbonate, removing the precipitated silver chloride and cautiously adding to the liquid dilute sulphuric acid a little silver chloride is thereby precipitated, it is removed by filtration, and the sulphate is precipitated from the filtrate by means of alcohol in carmine-red prisms. It is fairly soluble in water, and loses water if left over sulphuric acid or on heating to 100° C. 

Bromo-pentammino-chromic Bromide, [Cr(NH3)3Br]Br2, is prepared by transforming ehloro-pentammino-chloride into aquo-pentammino-chromic hydroxide, [Cr(NH3)5H20](0H)3, by means of silver oxide, treating the mixture with dilute hydrobromic acid, filtering off silver bromide formed, and allowing the filtrate to evaporate to small bulk. It is then heated with an equal volume of concentrated acid, the precipitate formed, collected, washed with dilute acid and alcohol.1 It crystallises in violet-red octahedra, and in solution the salt decomposes like the chloro-pentammino-salt warming with water and a little aeicl transforms the salt into aquo-pentammino-broniide silver oxide and water convert it into aquo-pentammino-hydroxide. 

Iodo-pentammino-chromic Salts, [Cr(NH3)sI]R2, resemble the chloro- and bromo-pentammino-salts. The iodide, [Cr(NH3)sI]I2, crystallises in bluish-violet octahedra, sparingly soluble in water and insoluble in alcohol the nitrate, [Cr(NH3)5I](X03)2, is a reddish-violet crystalline powder and the chloride, [Cr(NH3)5I]Cl2, is also a reddish-violet crystalline powder, fairly soluble in cold water, the solution of which is easily affected by light. All are prepared from the aquo-pentammino-ehromic salts on treatment with hydriodic acid.3... 

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