Pentanedionatobis ethylenediamine cobalt III ion

4-PENTANEDIONATOBIS-(ETHYLENEDIAMINE) COBALT (in) ION [Preparation and resolution of the acetylacetonatobis-(ethylenediamine) cobalt (III) ion] 

Racemic acetylacetonatobis(ethylenediamine)cobalt(III) ion was first prepared by Werner and Matissen from the hydroxoaquo complex. Later Werner, Schwyzer, and Kar-rer prepared the optical antipodes from the resolved chloro-aquobis(ethylenediamine)cobalt(III) cation. The present method describes an efficient preparation and a simple resolution of the racemic salt using sodium (-l-)-arsenyl tartrate as the resolving agent. 

Twenty-two grams (0.08 mol) of carbonatobis (ethylene-diamine) cobalt(III) chloride is treated with 80 ml. of 2 Af hydrochloric acid. When the reaction is complete, 16 ml. of acetylacetone (2,4-pentanedione) (0.16 mol) dissolved in 120 ml. of 1 M sodium hydroxide is added. The mixture is 

Thirty six grams of the racemic iodide is dissolved in 100 ml. of water at 80° and shaken with 21.9 g. of silver acetate for 10 minutes. The silver halide is filtered off and washed with 40 ml. of water. Forty and three-tenths grams of sodium (-l-)-arsenyl tartrate dissolved in 100 ml. of water is added to the cooled filtrate, and the solution is allowed to stand undisturbed for 40 hours. (The checkers report that it is necessary to cool the solution overnight at 3 to 4° to get the crystals.) The red needles of the diastereoisomer are filtered, washed with water and then acetone, and dried. The yield is 20 g. (80%). A 0.1% aqueous solution in a 1-dm. tube gave d = -f 0.31°, whence [a]o = H-310°. Anal. Calcd. for (-h)[Co(C2H8N2)2(C6H702)](-f )[C4H40eAs0]2 C, 26.99 H, 4.13 N, 7.41. Found C, 26.93 H, 4.35 N, 7.34. 

The diastereoisomer is suspended in 25 ml. of 1 A sodium hydroxide, and 30.0 g. of potassium iodide is added. The mixed red and white precipitate is filtered and suspended, while it is still damp, in 50 ml. of methanol, stirred for 5 minutes, and filtered. The white residue is washed with 

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