Nickel nitroprusside

Nickel nitroprusside, Ni[Fe(CN)5NO], obtained in a similar manner to the preceding salt,8 is dark green when anhydrous, but upon exposure to moist air becomes ashen grey. It is insoluble in acids, but readily dissolves in ammonia to a brownish yellow liquid. Potassium hydroxide turns it lemon-yellow. 

Except iron-palladium cyanide and nickel-nitroprusside, all complex cyanides are coloured. Therefore the colour of the solid settled after completion of the injection will indicate whether a reasonable distribution over the support has been achieved. Precipitation of cyanide... 

The characteristic colours and solubilities of many metallic sulphides have already been discussed in connection with the reactions of the cations in Chapter III. The sulphides of iron, manganese, zinc, and the alkali metals are decomposed by dilute hydrochloric acid with the evolution of hydrogen sulphide those of lead, cadmium, nickel, cobalt, antimony, and tin(IV) require concentrated hydrochloric acid for decomposition others, such as mercury(II) sulphide, are insoluble in concentrated hydrochloric acid, but dissolve in aqua regia with the separation of sulphur. The presence of sulphide in insoluble sulphides may be detected by reduction with nascent hydrogen (derived from zinc or tin and hydrochloric acid) to the metal and hydrogen sulphide, the latter being identified with lead acetate paper (see reaction 1 below). An alternative method is to fuse the sulphide with anhydrous sodium carbonate, extract the mass with water, and to treat the filtered solution with freshly prepared sodium nitroprusside solution, when a purple colour will be obtained the sodium carbonate solution may also be treated with lead nitrate solution when black lead sulphide is precipitated. 

Cobalt nitroprusside, Co[Fe(CN)6NO], obtained by double decomposition of a soluble cobalt salt with sodium nitroprusside, is a red salt, possessing an appreciable solubility in water. It dissolves in acids, but is insoluble in potassium hydroxide or ammonia solution. This latter property enables it to be separated from the corresponding nickel salt, which readily dissolves in ammonia.7... 

In this paper a study is presented on the preparation of a series of supported catalysts by precipitation of metal cyanide complexes in the presence of suspended supports. As supports alumina, titania, and silica, have been used. The metals studied comprise iron, cobalt, nickel, copper, manganese, palladium, and molybdenum. Both monometallic, bimetallic and even trimetallic cyanides were precipitated. The stoichiometry of the precipitated complexes was controlled by the valency of the metal ions and by using both nitroprusside and cyanide complexes. Electron microscopy was used to evaluate the distribution of the deposited complex cyanides on the supports. 57Fe-M6ssbauer spectra were measured on the dried precipitated complexes to gain information on the chemical composition of the iron containing complexes. 

Sulfur dioxide Zinc nitroprusside Induced oxidation of nickel hy- 3.5 445... 

The substance (20 — 30 mg) is heated in a silver or nickel crucible with 1—2 pellets of solid sodium hydroxide and kept in the melted state for 1 min. During the melting the evolution of basic vapors is tested with wetted litmus paper. The cooled and solidified melt is extracted with 3 ml of water and filtered. The alkaline filtrate (2 — 3 drops) is mixed with a few drops of 1% sodium nitroprusside solution to test the presence of sulfidic sulfur. The formation of a violet color proves the presence of bivalent sulfur in the tested substance. 

---