Tris ethylenediamine rhodium III Chloride Trihydrate

Tris(ethylenediamine)rhodium(III) chloride, first reported by Werner,1 was prepared by the reaction of sodium hexachloro-rhodate(III) dodecahydrate with ethylenediamine monohydrate. The reaction product, however, contained sodium chloride, which could not be removed by recrystallization,1 probably because of the formation of a double salt. J Jaeger2,8 prepared the compound from rhodium (III) chloride trihydrate and 50 % aqueous ethylenediamine. Gillard, Osborn, and Wilkinson4 carried out the reaction of rhodium(III) chloride 

Rhodium(III) chloride trihydrate (26.3 g., 0.10 mole) is placed in a 100-ml. round-bottomed flask which is then fitted with a condenser.. The flask is immersed in an ice bath, and an ice-cold mixture of 27 ml. (0.33 mole) of ethylenediamine monohydrate and 25 ml. of water is added through the condenser. The mixture should be added very carefully at first, and the whole addition should take at least 5 minutes as the initial reaction is very vigorous. The ice bath is removed (but kept at hand for controlling the reaction, if necessary). The reaction mixture is heated very carefully and finally refluxed until the rhodium chloride is dissolved (10-15 minutes). The solution is cooled for 15 minutes before 25 ml. of ethanol is added through the condenser. The mixture is boiled until the precipitate formed has redissolved, and the yellow solution is then allowed to stand at room temperature for 2 hours. During standing, white, needlelike crystals separate. Finally the mix- 

The combined filtrate and washings are evaporated to complete dryness. The residue is placed in an oven at 120°C. for 4 hours and is then dissolved in 15 ml. of hot water. Twelve milliliters of absolute ethanol is added to the solution, and the mixture is boiled until a clear solution has formed. The brownish solution is allowed to stand for 2 hours before cooling in ice. The precipitate is filtered, washed successively with 10-ml. portions of 60, 80, and 96% ethanol, and dried in air. The yield is approximately 9 g. 

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Tris(ethylenediamine)rhodium(III) chloride trihydrate (11.10 g., 0.025 mole) and 5.63 g. (0.0375 mole, 50% excess) of (+)-tartaric acid and 3.15 g. (0.075 mole) of LiOH-H20 are placed in a 100-ml. conical flask and dissolved in 25 ml. of boiling water. When a clear solution has formed, the solution is allowed to cool somewhat by standing for 5 minutes. Fifteen milliliters of ethanol is then added, and the solution is allowed to stand for 3 hours at room temperature with occasional shaking. During standing, white crystals of the tartrate double salt separate. The precipitate is filtered, washed with three 10-ml. portions of a 1 1 mixture of ethanol and water, and dried in air. The yield is approximately 8.3 g. 

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