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Cyclooctadiene rhodium chloride dimer

Cyclooctadiene rhodium chloride dimer
Other names Cyclooctadiene rhodium chloride dimer
CAS number 12092-47-6
Molecular formula C16H24Cl2Rh2
Molar mass 493.0806 g/mol
Melting point

243 °C<

Solubility in other solvents insol.
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Cyclooctadiene rhodium chloride dimer is the chemical compound with the formula Rh2Cl2(C8H12)2, commonly abbreviated Rh2Cl2(COD)2. This yellow-orange, air-stable compound is a widely used precursor to homogeneous catalysts.[1].

Preparation and reactions

The synthesis of Rh2Cl2(COD)2 involves treatment of hydrated rhodium trichloride with 1,5-cyclooctadiene in hot, deoxygenated aqueous ethanol in the presence of sodium carbonate:[1]

2 RhCl3(H2O)3 + 2 C8H12 + 2 CH3CH2OH + 2 Na2CO3 → [RhCl(C8H12)]2 + 2 CH3CHO + 8 H2O + 2 CO2 + 4 NaCl

Rh2Cl2(COD)2 is the principal source of the versatile electrophile "[Rh(COD)]+."

[RhCl(COD)]2 + n L → [LnRh(COD)]+Cl- (where L = PR3, alkene, etc.)

In this way, chiral phosphines such as "Chiraphos", "DIPAMP", "DIOP" have been attached to Rh. The resulting chiral catalysts are capable of asymmetrically hydrogenating certain prochiral alkenes.[2]


  1. ^ a b Giordano, G.; Crabtree, R. H. “Di-μ-chloro-bis(η4-1,5-cyclooctadiene)dirhodium(I)” Inorganic Syntheses, 1990, volume 28, pages 88-90. ISBN 0-471-52619-3.
  2. ^ Knowles, W. S., Advances in Synthesis and Catalysis 2003, volume 345, pages 3-13.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Cyclooctadiene_rhodium_chloride_dimer". A list of authors is available in Wikipedia.
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