Tetrairidium dodecacarbonyl

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.^[1][2][3] 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.

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 Y
3D model (JSmol)	Interactive image
ChemSpider	21171017
ECHA InfoCard	100.038.718
EC Number	242-607-5
PubChem CID	16211901
CompTox Dashboard (EPA)	DTXSID80474907
InChI InChI=1S/12CO.4Ir/c12*1-2;;;; Key: XWDKRVSSHIJNJP-UHFFFAOYSA-N
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). Y verify (what is YN ?) Infobox references

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.^[4] 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]⁻.^[5]

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⁻