Pentamethylcyclopentadienyl iridium dichloride dimer

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Pentamethylcyclopentadienyl iridium dichloride dimer
IUPAC name
Other names
12354-84-6 YesY
ECHA InfoCard 100.205.779
Molar mass 796.71 g/mol
Appearance orange solid
Melting point >230 °C
Dichloromethane, Chloroform
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

Pentamethylcyclopentadienyl iridium dichloride is an organometallic compound with the formula [(C5(CH3)5IrCl2)]2, commonly abbreviated [Cp*IrCl2]2 This bright orange air-stable diamagnetic solid is a reagent in organometallic chemistry.[1]

Preparation, structure, reactions[edit]

The compound has C2h symmetry. Each metal is pseudo-octahedral. It was first prepared by the reaction of hydrated iridium trichloride with hexamethyl dewar benzene.[2] More conveniently, the compound is prepared by the reaction of iridium trihydrate and pentamethylcyclopentadiene in hot methanol, from which the product precipitates[1]

2 Cp*H + 2 IrCl3(H2O)3 → [Cp*IrCl2]2 + 2 HCl + 6 H2O

The two Ir-μ-Cl bonds are labile and can be cleaved to give a variety of adducts of the general formula Cp*IrCl2L. Such adducts undergo further substitution to afford cations [Cp*IrClL2]+ and [Cp*IrL3]2+. The chloride ligands can also be replaced by other anions such as carboxylates, nitrite, and azide.

Reduction of [Cp*IrCl2]2 under an atmosphere of CO affords the dicarbonyl Cp*Ir(CO)2], which can be decarbonylated to give the unsaturated derivative [Cp*Ir(CO)]2.[3] Treatment of [Cp*IrCl2]2 with borohydride under an atmosphere of H2 gives the iridium(V) derivative Cp*IrH4.

[Cp*IrCl2]2 is a precursor to catalysts for the asymmetric transfer hydrogenation of ketones.[4]

[Cp*IrCl2]2 can be safely handled under air.


  1. ^ a b White, C.; Yates, A.; Maitlis, P. M. (1992). "(η5-Pentamethylcyclopentadienyl)Rhodium and -Iridium Compounds". Inorg. Synth. 29: 228–234. doi:10.1002/9780470132609.ch53. 
  2. ^ Kang, Jung W.; Moseley, K.; Maitlis, Peter M. (1969). "Pentamethylcyclopentadienylrhodium and -iridium halides. I. Synthesis and properties". J. Am. Chem. Soc. 91: 5970. doi:10.1021/ja01050a008. 
  3. ^ Ball, R. G.; Graham, W. A. G.; Heinekey, D. M.; Hoyano, J. K.; McMaster, A. D.; Mattson, B. M.; Michel, S. T. (1990). "Synthesis and structure of dicarbonylbis(.eta.-pentamethylcyclopentadienyl)diiridium". Inorg. Chem. 29: 2023. doi:10.1021/ic00335a051. 
  4. ^ Ikariya, T.; Blacker, A. J. (Dec 2007). "Asymmetric transfer hydrogenation of ketones with bifunctional transition metal-based molecular catalysts". Acc. Chem. Res. 40 (12): 1300–8. doi:10.1021/ar700134q. ISSN 0001-4842. PMID 17960897.