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Identifiers | |
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3D model (
JSmol)
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PubChem
CID
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Properties | |
C5CoN53− | |
Molar mass | 189.025 g·mol−1 |
Except where otherwise noted, data are given for materials in their
standard state (at 25 °C [77 °F], 100 kPa).
|
In chemistry, pentacyanocobaltate is the coordination complex with the formula [Co(CN)53−. When crystallized with a quaternary ammonium cation, it can be obtained as a yellow solid. Pentacyanocobaltate attracted attention as an early example of a metal complex that reacts with hydrogen. It contains low-spin cobalt(II), with a doublet ground state.
Aqueous solutions of pentacyanocobaltate are produced by the addition of five or more equivalents of a cyanide salt to a solution of a cobalt(II) salt. Initially this reaction produces insoluble cobalt dicyanide, but this solid dissolves in the presence of the excess cyanide. Pentacyanocobaltate forms within seconds. [1] When prepared using a quaternary ammonium (quat) cyanide, crystals can be obtained with the formula (quat)3[Co(CN)5. According to X-ray crystallography, the salt features square pyamidal [Co(CN)53−. [2]
Solutions of [Co(CN)53− undergo a variety of reactions. The complex attracted attention in the 1940s for its reactivity toward hydrogen, which is now understood to produce a cobalt hydride: [1]
When allowed to stand as a dilute solution for several minutes, the complex reacts with water to give two Co(III) derivatives:
In concentrated solution, the complex dimerizes:
With benzyl chloride and related alkylating agents, Co(III) alkyls are formed: [3]
![]() | |
Identifiers | |
---|---|
3D model (
JSmol)
|
|
PubChem
CID
|
|
| |
| |
Properties | |
C5CoN53− | |
Molar mass | 189.025 g·mol−1 |
Except where otherwise noted, data are given for materials in their
standard state (at 25 °C [77 °F], 100 kPa).
|
In chemistry, pentacyanocobaltate is the coordination complex with the formula [Co(CN)53−. When crystallized with a quaternary ammonium cation, it can be obtained as a yellow solid. Pentacyanocobaltate attracted attention as an early example of a metal complex that reacts with hydrogen. It contains low-spin cobalt(II), with a doublet ground state.
Aqueous solutions of pentacyanocobaltate are produced by the addition of five or more equivalents of a cyanide salt to a solution of a cobalt(II) salt. Initially this reaction produces insoluble cobalt dicyanide, but this solid dissolves in the presence of the excess cyanide. Pentacyanocobaltate forms within seconds. [1] When prepared using a quaternary ammonium (quat) cyanide, crystals can be obtained with the formula (quat)3[Co(CN)5. According to X-ray crystallography, the salt features square pyamidal [Co(CN)53−. [2]
Solutions of [Co(CN)53− undergo a variety of reactions. The complex attracted attention in the 1940s for its reactivity toward hydrogen, which is now understood to produce a cobalt hydride: [1]
When allowed to stand as a dilute solution for several minutes, the complex reacts with water to give two Co(III) derivatives:
In concentrated solution, the complex dimerizes:
With benzyl chloride and related alkylating agents, Co(III) alkyls are formed: [3]