Tris ethylenediamine chromium III Chloride

Five to ten grams of tris (ethylenediamine) chromium (III) chloride SU-hydrate are spread in a thin even layer on an open Petri dish embedded in a sand bath that carries a thermometer. The bath is maintained at 210°C until the product lias lost at least 25% of its original weight (theory = 80.6%). The evolution of amine soon begins and the yellow salt slowly darkens over a period of an hour or two, finally yielding a red-violet material. 

Tris(0,0 -diethyl dithiophosphato)-chromium(III), 6 142 Tris (ethylenediamine)chromium-(III) bromide, 4-hydrate, 2 199 Tris (ethylenediamine) chromium-(III) chloride, 3j-hydrate,... 

Methods for the preparation of tris(ethylenediamine)rhodium-(III) chloride hydrate and for its resolution by means of the diastereoisomer Ii (—)D-lRh(en)s] (- -)-tart 2 3H20 are presented. The resolution of tris(ethylenediamine)chromium(III) chloride by means of an analogous diastereoisomeric compound is also described. 

Tris(ethylenediamine)chromium(III) chloride trihydrate (39.3 g., 0.10 mole) and 22.5 g. (0.15 mole) of (+)-tartaric acid, and a magnetic stirring bar, are placed in a 400-ml. beaker. A 100-ml. volume of water is added, and the mixture is dissolved with stirring. Immediately after the dissolution, 12.6 g. (0.30 mole) of IiOH-H20 is added with continued stirring. The hydroxide dissolves, and shortly after a yellow crystalline precipitate is formed. About 5 minutes after the addition of the hydroxide, 100 ml. of ethanol is added dropwise with continued stirring during a 15-minute period. The precipitate is filtered, and the filtrate is run directly into a mixture of 15 ml. (0.18 mole) of 12 M HC1 and 600 ml. of absolute ethanol. From this system a finely crystalline precipitate of impure (—)D-chloride separates out. The filter flask is replaced, and the crystals are washed with three 50-ml. portions of a 1 1 mixture of ethanol and water and dried in air. (Yield is 27-28 g.) The precipitate of (—)D-chloride from the filtrate is filtered, washed with three 50-ml. portions of ethanol, and dried in air. (Yield is 13-14 g.)... 

It has been found4 that a good yield may be obtained rapidly by allowing the commercially available green chromic chloride, CrCl8-6H20, in methanol to boil under reflux with ethylenedi-amine in the presence of metallic zinc. The product, hydrated tris(ethylenediamine)chromium(III) chloride, is obtained as a solid and is readily purified. An exactly similar procedure may be used for the complex of 1,2-propanediamine. 

Molecules that coordinate strongly can often displace others from the coordination sphere. Ethylenediamine does not readily replace water from the hydrated chro-mium(III) ion, but it does readily displace pyridine. Pfeiffer has described the preparation of tris (ethylenediamine) chromium(III) chloride from trichlorotripyridine-chromium and the corresponding sulfate from dehydrated chrome alum. ... 

Cl2HsoCl6CoCrNi20s, (+) Tris(ethylenediamine)cobalt(III) (-) tris-(ethylenediamine)chromium(III) chloride hydrate, 42B, 729 Cl2H6oCl6CrNi20gRh, (+) Tris(ethylenediamine)chromium(III) (+)-tris-(ethylenediamine)rhodium(III) chloride hydrate, 42B, 729 Cl2H60CI7CO2N12NaOg, Sodium D-tris(ethylenediamine)cobalt(III) chloride hexahydrate, 19, 539 21, 547 Cl2H60CI7CO2N12NaOfi, Sodium L-tris-(ethylenediamine)cobalt(111) chloride hexahydrate, 19, 539... 

Ten grams of dl tris(ethylenediamine)chromium (III) thiocyanate monohydrate are heated at 130-135°C in an open Petri dish as for the cts-dichloro chloride (No. 124). The heating may be performed in a sand bath or thermostat oven. When the material lias lost at least 16% of its original weight (theory = 18.4%) the decomposition is complete for practical purposes. The crude material is quickly recrystallised from water at 50-60°C, filtered, then dried in air,... 

The tris(ethylenediamine) chromium (III) ion was first resolved by Werner6 by means of sodium 3-nitro-(+)-camphor. What has been said concerning the resolution of the corresponding rhodium compound holds true of the chromium compound, except that for the chromium compound the solubility difference of the diastereoisomeric chloride (+)-tartrates is so small that a resolution via these diastereoisomers has not been achieved.5,6 The method reported here is essentially the same as the one described for the rhodium complex but with minor alterations... 

The tris(ethylenediamine)chromium(III) salts (luteo chromic salts) are all markedly crystalline, orange-yellow substances. While the suKate is. extremely soluble and the chloride highly soluble in water, the bromide, iodide, and thiocyanate are relatively insoluble. All of these salts are slowly decomposed in cold water and rapidly in hot water, forming deep-red gummy materials, which are evidently hydroxoamminechromium compounds. The dry salts are slowly decomposed by exposure to light. The dry chloride and thiocyanate are decomposed readily by heat to bis(ethylenediamine) salts (synthesis 61). 

Exercises la. [CrCl4(NH3)2], diamminetetra-chlorochromate(III) ion. lb. [Fe(CN)6], hexa-cyanoferrate(in) ion. Ic. [Cr(en)3]2[Ni(CN)4]3, tris(ethylenediamine)chromium(III) tetra-cyanonickelate(II) ion. 3a. diamminesilver(I) chloride 3b. tetraamminediaquacopper(II) sulfate 3c dichlorido(l,2-ethanediamine) platinum(n) 3d. pentaaquabromi-dochromium (HI) ion 3e. rubidium tetrafluori-doargentate (IE) 3f. sodium pentacyanidooxi-donitrogenferrate(III)... 

RESOLUTION OF TRIS (ETHYLENEDIAMINE) -RHODIUM (IU) AND -CHROMIUM (III) CHLORIDE BY MEANS OF (+)-TARTRATE... 

C4H21CI4C0N4O2, trans Dichlorobis(ethylenediamine)cobalt(III) hydrochloride dihydrate, 16, 457 42B, 717 C4H2iCl4CrN402, trans-Dichlorobis(ethylenediamine)chromium(lll) chloride hydrochloride dihydrate, 24, 596 C4H2 aClCoNeOeSa, Tris(ammine)diethylenetriaminecobalt(111) chloride dithionate, 44B, 797... 

Tris(diamine) complexes of chromium(III) have been important from several viewpoints. First, the tris(ethylenediamine) complex is valuable as a synthetic intermediate,1 the action of heat on the chloride salt giving the cis-dichlorobis(ethylenediamine) complex and on the thiocyanate salt giving the irans-bis(iso-thiocyanato) complex. Second, the cations are resolvable, and studies2 of their optical activity have been fruitful in establishing relations between signs of Cotton effects and absolute stereochemistries. A large number of other studies, including kinetic and equilibrium measurements, have shown these complexes to be readily hydrolyzed to bis(ethylenediamine) complexes.3... 

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