NICKEL CYANIDE

Chemical Properties

Nickel cyanide is a yellowish-brown plates or powder that may change to a green color by absorbing moisture. Odor is a weak almond odor like cyanide.

Physical properties

The tetrahydrate, Ni(CN)₂?4H₂O constitutes apple green plates or powder; loses water of crystallization on heating at 200°C; decomposes on further heating; insoluble in water; slightly soluble in dilute acids; soluble in potassium cyanide solution and in ammonia, caustic soda, caustic potash and other bases.

Uses

Metallurgy, electroplating.

Preparation

Nickel cyanide is prepared by treating a soluble nickel salt, such as nickel chloride or nickel sulfate, with potassium cyanide solution: Ni²+ + 2CNˉ → Ni(CN)₂
The product is a tetrahydrate, Ni(CN)₂?4H₂O, which on heating at 200°C yields yellow-brown anhydrous salt, Ni(CN)₂.

Reactions

The most interesting reaction of nickel(II) cyanide is the formation of clathrate compounds in the presence of ammonia. When a solution of Ni(CN)2 in aqueous ammonia is shaken with benzene, a pale violet precipitate of the benzene clathrate Ni(CN)2?NH3?C6H6 is obtained. In this compound the Ni and CN groups form layers with ammonia molecules bonded above and below the planes of the layers on alternate nickel atoms. Thus half the nickel atoms are octahedrally surrounded by nitrogen (Ni-N=2.15 ?, N1-NH3 = 2.06 à) and half are planar 4-coordinated by carbon (Ni-C=1.76?). The benzene molecules occupy the holes (cages) formed between the layers. The average magnetic moment per nickel atom is 2.2 BM, and it has thus been established that the 4- coordinate nickel atoms are diamagnetic while the 6-coordinate atoms are paramagnetic with two unpaired electron spins.

General Description

NICKEL CYANIDE is an apple-green powder or a green crystalline solid. Insoluble in water. Toxic by inhalation and by ingestion. Carcinogenic. Produces toxic oxides of nitrogen in fires.

Air & Water Reactions

Insoluble in water.

Reactivity Profile

NICKEL CYANIDE is thermally unstable and easily oxidized. Weakly basic. Liberates flammable and lethally poisonous hydrogen cyanide gas on contact with acids or acid fumes. Undergoes violent reactions with fluorine, hypochlorites, nitric acid, nitrates, nitrites. Undergoes an explosive reaction if melted with nitrites or chlorates (at about 450°C). Emits highly toxic cyanide fumes when heated to decomposition. [Lewis, 3rd ed., 1993, p. 360, 912]. Undergoes an incandescent reaction if heated with magnesium [Mellor, 1940, vol. 4, p. 271].

Hazard

Highly toxic.

Health Hazard

DUST: POISONOUS IF INHALED. Irritating to eyes, nose and throat. SOLID: POISONOUS IF SWALLOWED. Irritating to skin and eyes.

Fire Hazard

Not flammable.

Safety Profile

Confirmed human carcinogen. A poison. Incandescent reaction when heated with magnesium. When heated to decomposition it emits very toxic fumes of CN-. See also CYANIDE and NICI(EL COMPOUNDS.

Potential Exposure

Nickel cyanide is used in metallurgy, electroplating and making other chemicals.

Shipping

UN1653 Nickel cyanide, Hazard Class: 6.1; Labels: 6.1-Poisonous materials. and equipped in OSHA 1910.156. The only respirators recommended for fire fighting are SCBAs that have full facepieces and are operated in a pressure-demand or other positive-pressure mode.

Incompatibilities

Nnickel cyanide is thermally unstable and easily oxidized. Weakly basic. Liberates flammable and lethally poisonous hydrogen cyanide gas on contact with acids or acid fumes. Undergoes violent reactions with fluorine, hypochlorites, nitric acid, nitrates, nitrites. Undergoes an explosive reaction if melted with nitrites or chlorates (at about 450 C). Violent reaction with magnesium. Keep away from acids, active metals, heat, or CO2; contact can cause release of toxic cyanide gas.

Waste Disposal

Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal.

Raw materials

Preparation Products