Magnesium cyanide is a chemical compound with the formula Mg(CN)
2. It is a toxic white solid. It has been theorized that it is a nitrile compound, but it has been disproved.
If heated to 500 °C, it decomposes to
magnesium nitride
Magnesium nitride, which possesses the chemical formula Mg3N2, is an inorganic compound of magnesium and nitrogen. At room temperature and pressure it is a greenish yellow powder.
Preparation
* By passing dry nitrogen over heated magnesium:
: ...
.
Preparation
The first attempt to prepare magnesium cyanide was attempted in 1924. It was attempted by reacting a solution of
hydrogen cyanide
Hydrogen cyanide, sometimes called prussic acid, is a chemical compound with the formula HCN and structure . It is a colorless, extremely poisonous, and flammable liquid that boils slightly above room temperature, at . HCN is produced on an ...
in water with magnesium metal:
:HCN + Mg → Mg(CN)
2 + H
2
However, no magnesium cyanide was observed, only
magnesium hydroxide
Magnesium hydroxide is the inorganic compound with the chemical formula Mg(OH)2. It occurs in nature as the mineral brucite. It is a white solid with low solubility in water (). Magnesium hydroxide is a common component of antacids, such as milk ...
formed. To avoid this problem, instead of using water as the reaction medium, pure
ammonia
Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous was ...
was used at -30 °C. This formed magnesium cyanide ammoniate, which in turn was heated to 180 °C to produce magnesium cyanide.
[A. R. Frank, R. B. Booth, American Cyanamid Co., US Patent 2419931, 1947.]
Other methods are possible, such as the decomposition of
magnesium ferricyanide in an electric carbon tube, which produces
iron carbide as a byproduct.
Complexes
Magnesium cyanide reacts with
silver nitrate
Silver nitrate is an inorganic compound with chemical formula . It is a versatile precursor to many other silver compounds, such as those used in photography. It is far less sensitive to light than the halides. It was once called ''lunar caustic' ...
to form magnesium silver cyanide, with the formula MgAg
2(CN)
4. When this compound is heated it produces
hydrogen cyanide
Hydrogen cyanide, sometimes called prussic acid, is a chemical compound with the formula HCN and structure . It is a colorless, extremely poisonous, and flammable liquid that boils slightly above room temperature, at . HCN is produced on an ...
gas and magnesium hydroxide in the presence of water, which meant it could not be used as a pathway for the production of magnesium cyanide. When silver nitrate reacts with magnesium cyanide, it also produces another magnesium silver cyanide, with the formula MgAg(CN)
3.
References
{{cyanides
Magnesium compounds
cyanides