Potassium cyanonickelate

Treat an aqueous suspension of about 0.072g (accurately weighed) silver chloride with a mixture of 10 mL of concentrated ammonia solution and 10 mL of 1M ammonium chloride solution, then add about 0.2 g of potassium cyanonickelate and warm gently. Dilute to 100 mL with de-ionised water, add 50 mg of the indicator mixture and titrate with standard (0.01 M) EDTA solution, adding the reagent dropwise in the neighbourhood of the end point, until the colour changes from yellow to violet. 

Potassium chloride (nitrate) bridge 583, 582 Potassium chromate as indicator, 343, 349 Potassium cyanoferrate(II) D. of, (ti) 384 Potassium cyanoferrate(III) D. of, (ti) 399 Potassium cyanonickelate(II) prepn., 328 Potassium dichromate solution analyses involving, 375 oxidising properties of, 375 internal indicators for, 377 preparation of, 0.02M, 375 redox indicators for, 377 standardisation of, by iron, (cm) 546, (ti) 376... 

Cyanonickelate(II) may be reduced to red cyanonickelate(I) ion in solution by nascent hydrogen. Red potassium cyanonickelate(I), K2[Ni(CN)3] has been isolated. X-ray structure indicates that this compound is a binuclear complex, potassium tetracyano-p-dicyanonickelate(I), K4[(CN)2Ni(CN)2Ni(CN)2]. 

In some procedures silver phosphate is formed by addition of silver nitrate to a slightly alkaline52 or acidic53 phosphate solution, then the precipitate is dissolved in ammoniacal potassium cyanonickelate, according to reaction 2. The displaced nickel is titrated with... 

POTASSIUM CUPROCYANIDE see PLC175 POTASSIUM CYANATE see PLC250 POTASSIUM CYANIDE see PLC500 POTASSIUM CYANIDE, solution (DOT) see PLC500 POTASSIUM CYANONICKELATE HYDRATE see TBW250... 

Reduction of aqueous solutions of potassium tetra-cyanonickelate(II), e.g., by hydroxylamine, potassium amalgam, or tin and sodium hydroxide, yields a red solu-... 

Ni(CN)2 Nickel cyanide, 2 228 NifCNlaKa-HaO Potassium tetra-cyanonickelate(II), 2 227, 228 Ni(CO)4 Nickel tetracarbonyl, 2 234... 

The formation of compounds containing the elements with less familiar oxidation states is another feature of chemistry in liquid ammonia solution . For example tetracyanonickelate(II) is reduced by potassium in liquid ammonia at —33° to the red cyanonickelate(I) , which is slowly reduced further at 0° to the yellow cyanonicklate(O) K4[Ni(CN)4] ... 

No cyanonickelate(I) is, however, obtained when cyanonickelate(II) is reduced by excess of potassium . Similarly the compounds K4[Co(CN)4] and K4[Pd(CN)4] 2 are produced, which contain the transition metals in the zero oxidation states. On the other hand the reduction of the cyanocomplex of chro-... 

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