Cyclooctadiene rhodium chloride dimer

Cyclooctadiene rhodium chloride dimer
IUPAC name di-μ-chlorido- bis[η2,η2-(cycloocta-1,5-diene)rhodium]
Other names Cyclooctadiene rhodium chloride dimer
Identifiers
CAS number	12092-47-6 Y
ChemSpider	21171524 Y
Jmol-3D images	Image 1
SMILES Cl[Rh].Cl[Rh].C=1CC\C=C/CCC=1.C/1C\C=C/CC\C=C\1
InChI InChI=1S/2C8H12.2ClH.2Rh/c2*1-2-4-6-8-7-5-3-1;;;;/h2*1-2,7-8H,3-6H2;2*1H;;/q;;;;2*+1/p-2/b2*2-1-,8-7-;;;; Y Key: QSUDXYGZLAJAQU-MIXQCLKLSA-L Y InChI=1/2C8H12.2ClH.2Rh/c2*1-2-4-6-8-7-5-3-1;;;;/h2*1-2,7-8H,3-6H2;2*1H;;/q;;;;2*+1/p-2/b2*2-1-,8-7-;;;;/r2C8H12.2ClRh/c2*1-2-4-6-8-7-5-3-1;2*1-2/h2*1-2,7-8H,3-6H2;;/b2*2-1-,8-7-;; Key: QSUDXYGZLAJAQU-PXXGERDABU
Properties
Molecular formula	C16H24Cl2Rh2
Molar mass	493.0806 g/mol
Melting point	243 °C<
Solubility in other solvents	dichloromethane
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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

Preparation and reactions

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

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

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

[RhCl(COD)]₂ + n L → [L_nRh(COD)]⁺Cl^- (where L = PR₃, alkene, etc. and n = 2 or 3)

In this way, chiral phosphines such as chiraphos, DIPAMP, and DIOP have been attached to Rh. The resulting chiral catalysts are capable of asymmetrically hydrogenating certain prochiral alkenes.