Cadmium cyanide

Preparation and structure

Cadmium cyanide is prepared commercially by treating cadmium hydroxide with hydrogen cyanide: : Cd(OH)2 + 2 HCN → Cd(CN)2 + 2 H2O It can also be generated from tetracyanocadmate: :[Cd(CN)4]2− + CdCl2 → 2 Cd(CN)2 + 2 Cl−

Cadmium cyanide and zinc cyanide adopt similar structures. As such, each metal has tetrahedral coordination sphere. Cyanide ligands interconnect pairs of metal centers. Two of the resulting diamondoid structures are interpenetrated. The structure is related to that of cristobalite, a polymorphs of SiO2. This structural similarity of cadmium dicyanide and cristobalite was foundational in the development of mineralomimetic chemistry: "the build-up of mineral-like structures using materials that never give stable minerals."

Reactions and uses

It is used as an electrolyte for electrodeposition of thin metallic cadmium coatings on metal to protect against corrosion.

Like zinc cyanide, cadmium cyanide is fairly soluble in water, which is unusual for transition metal cyanides. The solubility increases with the additional cyanide, this reaction proceeding via "[Cd(CN)3]−" and [Cd(CN)4]2−. With acids, its solutions evolve hydrogen cyanide. When it is crystallizes in the presence of certain small molecules, it forms clathrates.

References

References

1. (2014). "The Solubility of Some Sparingly Soluble Salts of Zinc and Cadmium in Water and in Aqueous Electrolyte Solutions". Journal of Physical and Chemical Reference Data.
2. {{PGCH. 0087
3. {{RubberBible87th
4. Karl-Heinz Schulte-Schrepping, Magnus Piscator "Cadmium and Cadmium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, 2007 Wiley-VCH, Weinheim. {{doi. 10.1002/14356007.a04_499.
5. {{Greenwood&Earnshaw2nd
6. (1997). "Mineralomimetic chemistry as a modern aspect of co-ordination chemistry". Journal of the Chemical Society, Dalton Transactions.