Cobaltate dinitro

Sargeson and co-workers have reported the use of [Pt(en)3]4+ in template reactions to produce the platinum(IV) complexes of the macrobicyclic ligands sep and (N02)2sar (170).477 These reactions are analogous to those that occur around cobalt(III). However, in contrast to the [Co((N02)2sar)]3+ system, reduction of the pendant dinitro groups did not yield amines, but hydroxyamine groups.478... 

Such a configuration should on replacement of one ammonia molecule by acidic or other monovalent radicle yield only one compound, and this is proved to be the case. On the other hand, if two acidic, or other groups replace two ammonia groups in the complex, isomerism should be possible, yielding two isomers of the formula [M(NII3)4R2 R. In the case of dinitro-tctrammino-cobaltic nitrate, [Co(NIi2)4(N02)2 N03, two isomeric forms are known to exist, one brown in colour, the other yellow. The two substances may be represented by the following formula —... 

Optical Activity in the Series.—Another type of isomerism is possible in the series, for the as-diehloro-salts present a case of molecular asymmetry similar to that observed in 1-, 2-dinitro-diethylenediamino-cobalt salts. Two configurations are possible, the one being the mirror image of the other, thus ... 

Nitro-aquo-tetrammino-cobaltic Nitrate, [Co(NH3)4H20(N02)] (N03)2, crystallises in brownish-yellow octahedra which are soluble in cold water. It is prepared from the chloride of the series or from dinitro-tetrainmino-cobaltie sulphate.2... 

Dinitro-tetrammino-cobaltic Salts, [Co(NH3)4(N02)2]It.—Two series of salts of this composition are known, the croceo-salts and the flavo-salts. The two are isomeric, and differ in colour and in method of preparation. They correspond to the isomeric series already described, the croceo-salts being the 1-, 6-, or trans-senes, and the flavo-salts the 1-, 2-, or eis-series. 

Dinitro-tetrammino-cobaltic Salts, Croceo-cobaltic Salts. 

Dinitro-tetrammino-cobaltic Nitrate, Croceo-cobaltic Nitrate, [Co(NH3)4(N02)2]N03, is formed when an aqueous solution of 1-, 6-dinitro-tetrammino-eobaltie sulphate is decomposed by the calculated quantity of barium nitrate.1 It crystallises in orange-yellow needles or prisms, is slightly soluble in cold, and soluble in hot, water. 

Dinitro-tetrammino-cobaltic Chloride, [Co(NH3)4(N03)2] Cl, is obtained from the sulphate by treating it with barium chloride, or by heating a solution of dichloro-tetrammino-cobaltic ehloride in dilute acetic acid with sodium nitrite.3 It is soluble in water, and separates from solution in reddish-yellow rhombic crystals. The aqueous solution, however, decomposes on standing. If a cold aqueous solution be treated with dilute nitric acid the nitrate separates concentrated hydrochloric acid decomposes the salt with formation of the chloro-nitro-chloride, [Co(NH3 )4 (NO 2)C1] Cl.3... 

Dinitro-tetrammino-cobaltic Nitrate, [Co(NH3)4(N02)2] N03, is prepared from carbonato-tetrammino-eobaltic nitrate by dis-... 

Acid dinitro-tetrammino-cobaltic Nitrate, [Co(NH3)4(N02)2] NOj.HNO,.—This compound is the first-formed product in the above reaction. It may be obtained by treating the normal nitrate with water and nitric acid. It forms glistening yellow-brown microscopic plates, and is decomposed by alcohol with formation of the normal nitrate. 

Dinitro - tetr ammino - cobaltic Sulphate, [Co (NH3)4(N02)2]2 S04, is formed from the nitrate by treating it with water and a solution of ammonium sulphate. The sulphate is precipitated, washed with water, and reerystallised from hot water containing acetic acid. 

The m-position is assigned to the carbonato-series, and this seems to be supported by the experimental evidence. Only one series of salts has been prepared, and these salts have been used in the determination of the configuration of the diacido-tetrammino-cobaltic salts. Thus, earbonato-tetrammino-cobaltie salts when treated with acid and sodium nitrite yield m-dinitro-tetrammino-salts. The reaction may be formulated ... 

Oxalato-tetrammino-cobaltic Chloride, [Co(NH3)4(C204)]C1, is prepared by dissolving chloro-aquo-tetrammino-eobaltic chloride in an aqueous solution of oxalic acid and heating the mixture for some time. The oxalato-compound gradually crystallises from the warm solution, and the crystals are collected and washed on the filter with alcohol until the filtrate is free from chlorine and from oxalic acid. It crystallises in carmine-red six-sided plates if dissolved in concentrated sulphuric acid and concentrated hydrochloric acid is added to the liquid, it is transformed into dichloro-tetrammino-cobaltic chloride. Sodium nitrite and acetic acid convert it into dinitro-tetrammino-cobaltic chloride.1... 

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. 

Dinitro-bis (ethylenediamine)-cobalt (III) nitrates see Di(ethylenediamine) and derivs 5 D1231... 

Classical methods for the synthesis of frans-dinitro-bis(ethylenediamine)cobalt(III) nitrate involve conversion of the cis isomer by heat1 or action of sodium nitrite on frans-chloronitrobis(othylenediamine)cobalt(III) nitrate.2 These methods involve isolation of intermediate coordination compounds and consequently are subject to low yields, based upon original cobalt(II) salt. The following procedure for the preparation of the trans compound gives an 84% yield it depends upon oxidation of cobalt(II) to cobalt(III) in the presence of sodium nitrite, ethylene-diamine, and nitric acid. 

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... 

It was her thesis work with Alfred Werner34 that was to enter her in the annals of the history of chemistry. Among the compounds she made was cis-bis(ethylenediamine)dinitro-cobalt(III) bromide. This was the very first synthesis of a chiral octahedral cobalt complex, though at the time the significance of her synthesis was overlooked.31(a) Werner was so impressed with her work that, for her last year, he took her on as his personal assistant, the first women to be chosen for this prestigious post.35 More important for the impoverished Humphrey, she at last had some income in very expensive Switzerland. 

When Co2(CX))8 is added to liquid dinitrogen tetroxide, either as the pure liquid or diluted with organic solvents, a slow reaction occurs and the addition compound Co(N03)2.2N204 is precipitated warming to 100° C. gives the anhydrous nitrate, Co(N03)2, and no nitrite has been observed in any product obtained from reactions in the liquid state. In contrast, cobalt carbonyl and dinitro-... 

Dinitro-bis(et1iy[enediamine)cobalt (III) nitrates, cis- and rrans- forms. Prepn and properties ace given in Ref 2. 

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,... 

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