Bromoamminebis ethylenediamine cobalt III Chloride

One and two-tenths grams (0.00275 mole) of (—)-cj5-bromoamminebis-(ethylenediamine)cobalt(III) dithionate from Sec. B is ground thoroughly with 4 ml of concentrated hydrochloric acid. The solution is allowed to stand in an ice bath for ca. 30 min, and the resulting deep red-violet crystals are collected by suction filtration. Additional product is obtained from the filtrate by addition of 12 ml of absolute ethanol. The combined crystals are dissolved in a minimum volume of water (ca. 4 ml), 2 ml of concentrated hydrochloric acid is added, and the solution is refrigerated overnight. The resulting crystals are collected by suction filtration, washed with absolute ethanol and ether, and then air-dried. The yield of (—)-chloride is 0.538 g (56.4%). For a 0.200% aqueous solution in a 2-dm tube, [aYc = —0.1886°, whence [or]p = —47.15° (Werner did not prepare the (—)-chloride, but he reported [aY = -t- 50.6° for the (+)-chloride the checkers report [a] = —50.6°). The checkers report =-155.2°. 

The active C(j-bromoamminebis(ethylenediamine)cobalt(III) salts, like the racemic compounds, are similar in properties to the corresponding cis-chloroamminebis(ethylenediamine)cobalt(III) salts, but they have been less extensively investigated. They are quite stable, and their solutions do not race-mize on standing at room temperature or even on heating to incipient boil-ing.i They can be converted from one salt to another without loss of optical activity. Treatment of the active bromide or(+)-a-bromocamphor- r-sulfonate with liquid ammonia yields the corresponding optically active cw-diammine-bis(ethylenediamine)cobalt(III) salts. A partial resolution of the racemic bromide into optical isomers on ( +)- and ( — )-quartz has been reported.The specific magnetic susceptibility has been found to be 3.49 X 

Measurements of light absorption, optical rotatory dispersion, the Cotton effect, and circular dichroism have been made.i i5 The mechanism, kinetics, and stereochemistry of the aquation and basic hydrolysis of [Coen2NH3Br] + complexes have been investigated. Change in optical activity with aquation has also been determined. 

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