Cyclooctadiene iridium chloride dimer

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Cyclooctadiene iridium chloride dimer
Ir2Cl2 cod 2improved.svg
Names
Other names
Bis(1,5-cyclooctadiene)diiridium(I) dichloride
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.031.961
EC Number 235-170-7
Properties
C16H24Cl2Ir2
Molar mass 671.70
Appearance red-orange solid
Density 2.65 g/cm3 (red polymorph)
Hazards
GHS pictograms The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word Warning
H302, H312, H315, H319, H335
P261, P264, P270, P271, P280, P301+312, P302+352, P304+340, P305+351+338, P312, P321, P322, P330, P332+313, P337+313, P362, P363, P403+233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Cyclooctadiene iridium chloride dimer is an organoiridium compound with the formula Ir2Cl2(C8H12)2, where C8H12 is the diene 1,5-cyclooctadiene. It is an orange solid that is soluble in organic solvents. The complex is used as a precursor to other iridium complexes, some of which are used in homogeneous catalysis.[1] The solid is air-stable but its solutions degrades in air.

Preparation, structure, reactions[edit]

The compound is prepared by heating hydrated iridium trichloride and cyclooctadiene in alcohol solvent. In the process, Ir(III) is reduced to Ir(I).[2]

In terms of its molecular structure, the iridium centers are square planar as is typical for a d8 complex. The Ir2Cl2 core is folded with a dihedral angle of 86°. The molecule crystallizes in yellow-orange and red-orange polymorphs; the latter one is more common.[3][4]

The complex is widely used precursor to other iridium complexes. A notable derivative is Crabtree's catalyst.[5] The chloride ligands can also be replaced to give diiridium complexes exhibiting modified reactivity, e.g. Ir2(OCH3)2(C8H12)2. A closely related but still more reactive complex is chlorobis(cyclooctene)iridium dimer.

See also[edit]

References[edit]

  1. ^ J. Hartwig, "Organotransition Metal Chemistry: From Bonding to Catalysis" University Science Books, 2009. ISBN 978-1891389535.
  2. ^ J. L. Herdé, J. C. Lambert, C. V. Senoff "Cyclooctene and 1,5-Cyclooctadiene Complexes of Iridium(I)" Inorganic Syntheses, 1974, Volume 15, pp. 18–20. doi:10.1002/9780470132463.ch5
  3. ^ F. Albert Cotton, Pascual Lahuerta, Mercedes Sanau, Willi Schwotzer "Air oxidation of Ir2(Cl)2(COD)2 revisited. The structures of [Ir(μ2-Cl)(COD)]2 (ruby form) and its oxidation product, Ir2Cl2(COD)22-OH)22-O)" Inorganica Chimica Acta, 1986 vol. 120, Pages 153–157. doi:10.1016/S0020-1693(00)86102-2
  4. ^ Tabrizi, D., Manoli, J. M., Dereigne, A., "Etude radiocristallographique de μ-dichloro-bis (π cyclooctadiène-1,5) diiridium: [(COD-1,5)IrCl]2, variété jaune-orange", Journal of the Less Common Metals 1970, vol. 21, pp. 337. doi:10.1016/0022-5088(70)90155-4
  5. ^ Robert H. Crabtree, Sheila M. Morehouse "[η4-1,5-Cyclooctadiene)(Pyridine)-(Tricyclohexylphosphine)Iridium(I)Hexafluorophosphate" Inorganic Syntheses, 1986, Volume 24, pp. 173–176. doi:10.1002/9780470132555.ch50