Tetrairidium dodecacarbonyl

Tetrairidium dodecacarbonyl
Names
	IUPAC names dodecacarbonyl-1κ3C,2κ3C,3κ3C,4κ3C-[Td-(13)-Δ4-closo]-tetrairidium(6 Ir—Ir); tetrahedro-tetrakis(tricarbonyliridium)(6 Ir—Ir)
	Other names iridium(0) carbonyl; iridium carbonyl; iridium dodecacarbonyl
Identifiers
CAS Number	18827-81-1;
3D model (JSmol)	Interactive image;
ECHA InfoCard	100.038.718
CompTox Dashboard (EPA)	DTXSID80474907 ;
	SMILES [O+]#C[Ir-3]12(C#[O+])(C#[O+])[Ir-3]3(C#[O+])(C#[O+])(C#[O+])[Ir-3]1(C#[O+])(C#[O+])(C#[O+])[Ir-3]23(C#[O+])(C#[O+])C#[O+];
Properties
Chemical formula	Ir4(CO)12
Molar mass	1104.92 g/mol
Appearance	Canary-yellow crystals
Melting point	195 °C (383 °F; 468 K)
Solubility	Chlorocarbons, toluene, tetrahydrofuran
Related compounds
Related compounds	Tetrarhodium dodecacarbonyl
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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	Infobox references

Tetrairidium dodecacarbonyl is the chemical compound with the formula Ir₄(CO)₁₂. This tetrahedral cluster is the most common and most stable "binary" carbonyl of iridium. This air-stable species is only poorly soluble in organic solvents. It has been used to prepare bimetallic clusters and catalysts, e.g. for the water gas shift reaction, and reforming, but these studies are of purely academic interest.

Structure

Each Ir center is octahedral, being bonded to 3 other iridium atoms and three terminal CO ligands. Ir₄(CO)₁₂ has T_d symmetry with an average Ir-Ir distances of 2.693 Å.[1] The related clusters Rh₄(CO)₁₂ and Co₄(CO)₁₂ have C_3v symmetry because of the presence of three bridging CO ligands in each.

Preparation

It is prepared in two steps by reductive carbonylation of hydrated iridium trichloride. The first step gives [Ir(CO)₂Cl₂]⁻.[2]

IrCl₃ + 3 CO + H₂O → [Ir(CO)₂Cl₂]⁻ + CO₂ + 2 H⁺ + Cl⁻

4 [Ir(CO)₂Cl₂]⁻ + 6 CO + 2 H₂O → Ir₄(CO)₁₂ + 2 CO₂ + 4 H⁺ + 8 Cl⁻

References

Churchill, Melvyn Rowen; Hutchinson, John P. (1978). "Crystal Structure of tetrairidium dodecacarbonyl, Ir₄(CO)₁₂. An Unpleasant Case of Disorder". Inorganic Chemistry. 17 (12): 3528–35. doi:10.1021/ic50190a040.CS1 maint: uses authors parameter (link)
Pergola, R. D.; Garlaschelli, L.; Matinengo, S. (1990). "Dodecacarbonyltetrairidium: Ir₄(CO)₁₂". Inorganic Syntheses. 28: 245–247. doi:10.1002/9780470132593.ch63. ISBN 9780470132593.

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[1] Churchill, Melvyn Rowen; Hutchinson, John P. (1978). "Crystal Structure of tetrairidium dodecacarbonyl, Ir₄(CO)₁₂. An Unpleasant Case of Disorder". Inorganic Chemistry. 17 (12): 3528–35. doi:10.1021/ic50190a040.CS1 maint: uses authors parameter (link)

[2] Pergola, R. D.; Garlaschelli, L.; Matinengo, S. (1990). "Dodecacarbonyltetrairidium: Ir₄(CO)₁₂". Inorganic Syntheses. 28: 245–247. doi:10.1002/9780470132593.ch63. ISBN 9780470132593.