Chemical Properties
green powder
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?4H
2O 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: Ni
2+ + 2CNˉ → Ni(CN)
2The product is a tetrahydrate, Ni(CN)
2?4H
2O, 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].
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.
