Cobalt chloride hydrates

CsHisClCoNfl03S H2O, Bis(ethylenediamine)(thiooxalato-0,S)cobalt chloride hydrate, 46B, 946... 

Cobalt II) halides can be obtained by direct combination of the elements, or by dehydration of their hydrates. Anhydrous cobalt(II) chloride is blue, and the solid contains octahedrally-coordinated cobalt the hydrated salt C0CI2. bHjO is pink, with each cobalt surrounded by four water molecules and two chloride ions in a distorted octahedron. 

Cobalt, dibromobis(l,2-propancdiamine)-chloride hydrate halogen exchange, 1, 468 Cobalt, dibromotris(difluorophenylphosphine)-structure, 1, 45... 

Cobalt, dichlorobis(AvY -dimethyl-1,2-ethanediamine)-chloride hydrate isomerization, 1, 468 Cobalt, dich orobis(l,2-ethanediamine)-base hydrolysis, 1, 304 chloride anation, 1, 469 halogen exchange, 1, 468 chloride hydrate isomerization, 1, 468 isomers, 1,191 nitrate... 

Three color changes were observed blue, violet and red. From the information provided, the blue form appeared to be the anhydride, CoCl2. When exposed briefly to air containing water vapor, the anhydrous cobalt chloride turned violet, CoCl2 2H20. Upon further standing in air, the dihydrate was converted to the fully hydrated form, CoCl2 6 H20. The color of the anhydride-hydrate depended upon the relative humidity of the air to which it was exposed. 

Hydrate Isomerism.—As its name implies, this depends on the position of water in the molecule, just as in the case of the acido compounds. If two or more molecules of water are present in a molecule of ammine, the water may be present within the co-ordination complex or outside of it. For instance, the compound Cr en2.(H20)2.Br3 exists in isomeric forms. It may have all the water within the complex, in which case the formula will be [Cr en2(H20)2]Br3. In solution the whole of the bromine is precipitated by silver nitrate. On the other hand, the compound may have one molecule of water in the complex and the other outside, in which case the formula is [Cr en2(IT20)Br]Br2.H20, and only two-thirds of the bromine are precipitated by silver nitrate. Another example of this kind occurs in the cobalt series chloro-aquo-tetrammino-cobaltic chloride, [Co(NTI3)4Cl.H20]Cl2, is violet in colour, and is isomeric with dichloro-tetrammino-cobaltie chloride monohydrate, [Co(N1I3)4CI2]C1.H20, which is green. 

Forty grams of cobalt carbonate are combined with a mixture of concentrated hydrochloric acid and 40ml of water are used or a solution of 80g of cobalt chloride 6-hydrate in 106ml of hot water. The oxidized solution is... 

Hydrated cobalt chloride crystals, CoC12.6H20, were heated in the apparatus shown below. 

Cobalt (Co) Cobalt is a silvery white metal. Cobalt chloride absorbed onto a piece of felt can measure the relative humidity in air. When the air is humid, cobalt chloride picks up water from the air to form a reddish purple hydrate. When the air is dry, cobalt chloride releases the water of hydration and turns blue. 

The only definite borate hydrates of cobalt are the CoO - 3B203 - 8H20 and CoO 3B203 10H2O compounds. The octahydrate is prepared by evaporation of acetic acid from cobalt acetate-boric acid mixtures, or by mixing aqueous solutions of cobalt chloride, borax, and boric acid (206). The 1 3 7.5 borate can form as a solid solution and, in the presence of 3% boric acid, affords the decahydrate (117). The crystal structure determination of this 1 3 10 compound shows it to possess the hexaborate ion (380). The IR spectra (402) and thermal decomposition (396) of these compounds have been determined. 

This simple hydration theory cannot explain all the known phenomena, as, for example, the opposite effects of calcium chloride and zinc chloride on the colours. Engel2 therefore assumed that the observed colours were due to certain double salts present in the solutions. In the case of pure cobalt chloride, hydrolysis was supposed to occur on heating the solution, the hydrochloric acid liberated uniting with unchanged cobalt chloride and as an explanation of the colour change this is almost certainly incorrect. Ostwald 3 suggested a simple ionic explanation, namely, that the red colour is that of the cobalt cation, and the blue that of the undissociated salt. This is certainly not a complete explanation, and seems to necessitate a very marked decrease in ionisation with rise of temperature, which experiment, so far, does not support.4... 

ICotschubei6 has determined the extent of the hydration of the cobalt ion in cobalt chloride solution by the electrolytic method briefly indicated in the first volume of this Series,6 and finds that the hydration increases with the dilution. He concludes from his own and other workers experiments that the hydration diminishes with rise of temperature also that the hydration of the cobalt chloride molecule varies in the same manner as that of the cobalt ion. He doubts the existence of complex ions in solutions of cobalt chloride, and considers that in the blue solutions formed by the addition of hydrochloric acid, calcium chloride, etc., the evidence for the existence of complex ions is inconclusive. On the other hand, he admits the presence of complex... 

Cobaltic Chloride, CoCl3, has not as yet been isolated, although indications of its possible existence are not entirely wanting. Thus, when freshly precipitated hydrated cobaltic oxide is dissolved in alcoholic hydrogen chloride, a dark green solution is produced which rapidly turns to a rose colour.9 The first dark colour suggests the presence of trivalent cobalt. 

Potassium Cobaltous Nitrite, 2KN02.Co(N02)2. H20, is obtained by adding potassium nitrite to a neutral solution of cobalt chloride. It is precipitated as a yellow, hydrated mass, which is soluble in hot water to a red solution.6... 

Conjugated dienes can be reduced to monoolefins by treatment with hydrogen, hydrated cobalt chloride, potassium cyanide, potassium chloride, sodium hydroxide, and tetramethylammonium chloride or benzyltri-ethylammonium chloride as the phase-transfer catalyst. The hydridopen-tacyanocobaltate anion, HCo(CN)s3, is the probable metal catalyst (47-... 

Figure 11-13 shows a common hydrate of cobalt(ll) chloride. If 11.75 g of this hydrate is heated, 9.25 g of anhydrous cobalt chloride remains. What is the formula and name for this hydrate ... 

Problem In order to also obtain a solid substance which shows a regular octahedral complex, from pink colored cobalt(II) chloride hydrate the yellow colored ammine complex of cobalt(III) ions is formed [Co(NH3)6]3 +. However, the cobalt(II) chloride has to be oxidized with hydrogen peroxide - a cross-linkage to redox reactions (see Chap. 8) is possible. 

Cobalt, dichlorobis(Af,. V -dimethylethylenediamine)-chloride hydrate isomerization, 468... 

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