Bis ethylenediamine dinitrocobalt III Nitrite

5-mole) sample of crude (carbonato)bis(ethyl-enediamine)cobalt(III) chloride is added with stirring to 275 ml. of 4 M hydrochloric acid cooled to 0-5°C. in an ice bath. The 

One hundred fifty milliliters of 12 M hydrochloric acid is added to a solution containing 195 g. (0.82 mole) of cobalt(II) chloride hexahydrate in 175 ml. of water. The cobalt(II) chloride solution is cooled in an ice bath and stirred during addition of the acid. This solution is treated with a solution of 900 g. (13.1 moles) of sodium nitrite in 775 ml. of water, and m-bis(ethylenediamine)-dinitrocobalt(III) nitrite is isolated as described above. The yield is 178 g. of the impure nitrite salt (68.5% based on cobalt(II) chloride). Anal. Found Co, 18.98 C, 14.85 H, 5.08 N, 29.51. 

The cis configuration has been confirmed by conversion of the crude nitrite salts into the bromide salt and resolution of the 

Properties are reported in previous volumes in this series.9 10 

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Besides (carbonato)bis(ethylenediamine)cobalt(III) chloride and the corresponding bromide salt, the following complexes are described cis- and frara -dichlorobis(ethylenediamine)cobalt(III) chloride, cts-aquachlorobis(ethylenediamine)cobalt(III) sulfate, cis-bis(ethylenediamine)dinitrocobalt(III) nitrite, m-aquabis-(ethylenediamine)hydroxocobalt(III) dithionate, and cis-diaqua-bis(ethylenediamine)cobalt(III) bromide. 

The tetraamminedinitrocobalt(lll) salts represent the second longest known case of geometric isomerism among coordination compounds. The reddish-yellow trans compounds were first prepared in 1875 by air oxidation of a solution of cobalt(II) chloride containing ammonia, sodium nitrite, and ammonium chloride by Wolcott Gibbs, who called them croceo salts. The brownish-yellow cis compounds were first prepared in 1894 by reaction of tetraamminecarbonato-cobalt(III) salts with sodium nitrite by Jorgensen, who called them flavo salts. The two series correspond completely to the bis(ethylenediamine)dinitrocobalt-(111) salts. 

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