Tetracobalt dodecacarbonyl

Tetracobalt dodecacarbonyl
Names
	Other names cobalt dodecacarbonyl, cobalt carbonyl
Identifiers
CAS Number	17786-31-1;
3D model (JSmol)	Interactive image;
ECHA InfoCard	100.037.951
CompTox Dashboard (EPA)	DTXSID20939000 ;
	SMILES [Co-2]1235(C#[O+])(C#[O+])C(=O)[Co-2]246(C#[O+])(C#[O+])C(=O)[Co-2]34(C#[O+])(C#[O+])(C1=O)[Co-3]56(C#[O+])(C#[O+])C#[O+];
Properties
Chemical formula	Co4(CO)12
Molar mass	571.858 g/mol
Appearance	black crystal
Density	2.09 g/cm3
Melting point	decomposes at 60 °C (140 °F; 333 K)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
	Infobox references

Tetracobalt dodecacarbonyl is the chemical compound with the formula Co₄(CO)₁₂. It is a black crystalline compound that is insoluble in water and easily oxidized by air. It is an example of a metal carbonyl cluster.

Synthesis and structure

This compound is synthesized by decarbonylation of Co₂(CO)₈.

2 Co₂(CO)₈ → Co₄(CO)₁₂ + 4 CO

The molecule consists of a tetrahedral Co₄ core, but the molecular symmetry is C_3v. Three carbonyl ligands are bridging ligands and nine are terminal.[1] The average Co-Co distance is 2.499 Å, the average C-O bond length is 1.133 Å, and the average Co-C-O angle is 177.5°.[2][3]

Rh₄(CO)₁₂ adopts the same C_3v structure but Ir₄(CO)₁₂ has perfect T_d symmetry with no bridging CO ligands groups.[4] The Rh₄ and Ir₄ clusters are more thermally robust than that of the Co₄ compound, reflecting the usual trend in the strengths of metal-metal bond for second and third row metals vs those for the first row metals.

References

Chini, P. (1968). "The closed metal carbonyl clusters". Inorganica Chimica Acta: 31–51. doi:10.1016/0073-8085(68)80013-0.
Farrugia, L. J.; Braga, D.; Grepioni, F. (1999). "A structure redetermination of Co₄(CO)₁₂: evidence for dynamic disorder and the pathway of metal atom migration in the crystalline phase". Journal of Organometallic Chemistry: 60–66. doi:10.1016/S0022-328X(98)00879-1.
Corradini, P. (1959). "Structure of tetracobaltdodecarbonyl". Journal of Chemical Physics: 1676–1677. doi:10.1063/1.1730674.
Wei, C. H. (1969). "Structural analyses of tetracobalt dodecacarbonyl and tetrarhodium dodecacarbonyl. Crystallographic treatments of a disordered structure and a twinned composite". Inorganic Chemistry: 2384–2397. doi:10.1021/ic50081a030.

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[1] Chini, P. (1968). "The closed metal carbonyl clusters". Inorganica Chimica Acta: 31–51. doi:10.1016/0073-8085(68)80013-0.

[2] Farrugia, L. J.; Braga, D.; Grepioni, F. (1999). "A structure redetermination of Co₄(CO)₁₂: evidence for dynamic disorder and the pathway of metal atom migration in the crystalline phase". Journal of Organometallic Chemistry: 60–66. doi:10.1016/S0022-328X(98)00879-1.

[3] Corradini, P. (1959). "Structure of tetracobaltdodecarbonyl". Journal of Chemical Physics: 1676–1677. doi:10.1063/1.1730674.

[4] Wei, C. H. (1969). "Structural analyses of tetracobalt dodecacarbonyl and tetrarhodium dodecacarbonyl. Crystallographic treatments of a disordered structure and a twinned composite". Inorganic Chemistry: 2384–2397. doi:10.1021/ic50081a030.