Cobaltate dinitro potassium

The crude substance is their recrystallised from water containing acetic acid. The compound was originally believed to exist in two isomeric forms, but Jorgensen found the crystalline form depends on the concentration of acetic acid used for crystallisation, inasmuch as rhombic leaflets separate from hot dilute acetic acid, and from hot concentrated acid the substance separates in yellow-brown needles. The complex is sparingly soluble in water, and gives no precipitate in aqueous solution with silver nitrate or potassium chromate. If treated with cold hydrochloric acid it is transformed into chloro-dinitro-triammino cobalt, [Co(NH3)3(N02)2Cl], and if warmed with concentrated hydrochloric acid gives diehloro-aquo-triammino-cobaltic chloride. 

Ammonium Tetranitrito - diammino - cobaltate, [Co(XH3)2 (N02)4]NH4, is prepared from cobaltous chloride by mixing an aqueous solution of the salt with aqueous ammonium-chloride solution, sodium nitrite, and ammonia, and oxidising the mixture by passing air through it for several hours. The solution is allowed to stand in air for some days, when crystals gradually separate. These are collected, washed, and reerystallised from water.3 The substance crystallises in brown rhombic prisms. It is decomposed on treatment with potassium hydroxide with evolution of ammonia, and a cold solution reacts with ammonia in presence of ammonium salts, with formation of flavo-dinitro double salts, of which [Co(NH3)4(N02)2][Co(NH3)2(N02)4] is typical. Oxalic acid transforms it into the oxalato-dinitrito-diammino-salt, [Co(NH3)2(N02)2(C204)]NH4. 

The configurations of the cis and trans forms of dinitro-bis(ethylenediamine)cobalt(III) ion were established by Werner,4 who resolved the cis form into its optical antipodes. The cis and trans isomers may also be distinguished chemically by utilization of the fact that a warm aqueous 3 % solution of the cis form yields precipitates when treated with concentrated solutions of potassium chromate, ammonium oxalate, or sodium thiosulfate a warm 10% solution of the trans form gives no precipitate with any of these reagents.3... 

CoKn407CH O.5H2O, Cobaltate(III), diammine(carbonato)dinitro-, cis,cis-, potassium, hemihydrate, 23 70 C0KN4O8C2H6 O.5H2O, Cobaltate(III), diamminedinitro(oxalato)-, cis,cis-, potassium, hemihydrate, 23 71 C0KO2, Potassium cobalt oxide, 22 58 C0K0.SO2, Potassium cobalt oxide,... 

From the minor fraction, potassium franr-(N02)-diammine-dinitro-oxalato-cobaltate(III) monohydrate is obtainable.2... 

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