Erdmann’s salt

Erdmann,1 in 1866, prepared the first member of this series, namely, ammonium tetranitrito-diammino-cobaltate, [Co(NH3)2(N02)4] NH4. The salt is sometimes referred to as Erdmann s salt on that account. Later, Gibbs prepared other salts of the same type, and showed that in these salts the cobalt atom, united with ammonia and acidic radicles, forms a negative radicle.2 Werner then showed that these salts form the connecting link between the neutral un-ionised complex triacido-triammino-eobalt compounds and the double salt, such as potassium eobalti-nitrite. Thus, by replacement of ammonia molecules by acid radicles a transition takes place from trinitrito-triammino - cobalt to potassium tetranitrito - diammino - cobaltate, [Co(NH3)2(N02)4]K, then to potassium pentamtrito-ammino-eobalfate. [Co(NH3)(N02)5]K, and finally to hexanitrito-cobaltate, [Co(N02)e]Iv3. Tetra-acido-diammino-cobaltates are therefore the salts of the acid tetra-acido-diammino-cobaltic acid, [Co(NH3)2R4]H. 

In complexes C0A4B2 (and more complex types) the structural study is necessary to establish unambiguously the relative arrangement of the ligands, e.g. the trans arrangement of the Q atoms in [Co(NH3)3(H20)Cl2] and of the two NH3 molecules in [Co(NH3)2(N02)4]. The latter ion, of Erdmann s salt, had been assigned the cis configuration on the basis of self-consistent chemical evidence. 

Thus, two isomers of triammmetrinitrocobalt(III) were finally recognized after more than hundred years of research. However, a complex, cu-[Co(N02)4(NH3)2] , is still missing in this series, although the corresponding trans isomer is the very familiar Erdmann s salt, NH4[Co(N02)4(NH3)2]... 

Erdmann s salt ammonium tetranitro diammine cobaltate NH4[Co(NH)2(NO)4]... 

New problems on chain theory, Werner and modern representations of tetrahedral and square planar platinum complexes, providing modern name of Erdmann s salt, and naming bridged complexes... 

In 1839 Mosander heated some cerium nitrate and treated tire partly decomposed salt with dilute nitric acid. In the extract he found a new earth, which he named lanthana, meaning hidden, meanwhile retaining the old name, ceria, for the oxide which is insoluble in dilute nitric acid (7, 28, 45). In the same year, Axel Erdmann, one of Sefstrom s students, discovered lanthana in a new Norwegian mineral, which he named mosan-drite in honor of Mosander. 

O. L. Erdmann reported potassium cobaltous tetranitrite, K2Co(N02)4, or 6K0H.3Co3(N02)2, to be separated as a yellow crystalline powder when soln. of cobaltous chloride and an excess of potassium nitrite are mixed. No oxygen is absorbed from the air during its formation, and O. L. Erdmann, and S. P. Sadtler used an atm. of carbon dioxide. The salt was also prepared by A. Stromeyer, and C. D. Braun. The salt is insoluble in cold water, but soluble in hot water, forming a red soln. It forms a violet soln. if potassium acetate is present, containing cobaltous salts. The salt decomposes when heated. C. D. Braun said that cobaltic hydroxide is precipitated when the soln. is boiled with potash-lye. 0. L. Erdmann said that the cobalt is not contained in the salts as a base in the... 

The brown rhombic prisms were shown by F. M. Jager to have the axial ratios a b c=0-8837 1 0-5226 and a sp. gr. 1-933 at 15°. The salt develops ammonia when treated with potassium hydroxide. This salt can be used as a starting point for the preparation of some other ammines. According to S. M. Jorgensen, with ammonia, it forms the cobaltic dinitritotetrammine tetranitritodiamminocobaltiate. 0. L. Erdmann prepared potassium tetranitritodiamminocobaltiate, K[Co(NH3)2(N02)], by adding potassium nitrite to a soln. of cobaltous and... 

Ammonium Cobalti-nitrite, 4(NH4)3Co(N02)s.3Ha0, was first prepared in 1856 by Gibbs and Genth. Erdmann 2 obtained it by the action of ammonium nitrite upon cobalt chloride solution acidulated with acetic acid. It may also be obtained by adding semicarbazide to a solution of sodium cobalti-nitrite 3 and by double decomposition of solutions of ammonium chloride and sodium cobalti-nitrite or by addition of nitrous acid to a suspension of cobalt carbonate in the requisite quantity of ammonium nitrite solution.4 In all three cases the salt is precipitated out. 

Triamminetrinitrocobalt(III)> tCo(N02)j(NH3)3], was first prepar in 1866 by Erdmann, later by Werner and Jorgensen, who prepared the complex by the air-oxidation of ammoniacal cobalt(II) salt solutions containing sodiiun nitrite and a large amount of ammonium chloride. In 1938, Duval examined the products obtained from several different procedures by absorption and infrared spectroscopy, refractive index of aqueous solutions, conductivity, and X-ray powder diffraction. He recognized two products in the Werner s preparation and the Jorgensen s preparation. In that year, Sueda reported an isomeric complex from the reaction of the [Co(N03)j(NH3)3] complex with sodium nitrite in a cold aqueous solution, which was assumed to be cis-cis isomer on the basis of the absorption spectrum. 

Whilst in Bordeaux, Laurent isolated pimaric acid from pine tar. From coal tar he isolated phenol (hydrate de phenyle ou acide phenisique) and obtained picric acid by nitrating it. He proved that phenol is identical with the carbolic acid (karbolsaure) discovered in coal tar by Runge. Laurent described the preparation of purer specimens of chlorophenols and showed that the chlorindoptic acid prepared by Erdmann from indigo is pentachloro-phenol. Laurent prepared trinitrophenol (acide nitrophenisique) and its salts and showed that it is identical with the substance discovered by Woulfe (see Vol. Ill, p. 301) and named picric acid (acide picrique) by Dumas (m/cpo , bitter), who translated as acide carbazotique Liebig s name kohlenstickstoff-saure. The chrysoleptic acid obtained by the action of nitric acid on aloes by Schunck he himself found was picric acid. 

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