Cyclooctadiene rhodium chloride dimer

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Cyclooctadiene rhodium chloride dimer
Cyclooctadiene-rhodium-chloride-dimer-2D-skeletal.png
Cyclooctadiene-rhodium-chloride-dimer-3D-balls.png
Names
IUPAC name
di-μ-chlorido-bis[η22-(cycloocta-1,5-diene)rhodium]
Other names
Cyclooctadiene rhodium chloride dimer
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.031.949 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 235-157-6
PubChem CID
  • 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-;;;; Yes check.svgY
    Key: QSUDXYGZLAJAQU-MIXQCLKLSA-L Yes check.svgY
  • 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
  • Cl1[Rh]Cl[Rh]1.C=1CC\C=C/CCC=1.C/1C\C=C/CC\C=C\1
Properties
C16H24Cl2Rh2
Molar mass 493.0806 g/mol
Density 1.93 g/cm3
Melting point 243 °C (469 °F; 516 K)
Solubility dichloromethane
Hazards
GHS labelling:
GHS-pictogram-exclam.svg GHS-pictogram-pollu.svg
Warning
H302, H315, H317, H319, H335, H411
P261, P264, P270, P271, P272, P273, P280, P301+P312, P302+P352, P304+P340, P305+P351+P338, P312, P321, P330, P332+P313, P333+P313, P337+P313, P362, P363, P391, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Cyclooctadiene rhodium chloride dimer is the organorhodium 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. [1]

Contents

Preparation and reactions

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

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

[RhCl(COD)]2 is principally used as a source of the electrophile "[Rh(COD)]+."

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

In this way, chiral phosphines can be attached to Rh. The resulting chiral complexes are capable of asymmetric hydrogenation. [3] A related but still more reactive complex is chlorobis(cyclooctene)rhodium dimer. The dimer reacts with a variety of Lewis bases (L) to form adducts with the stoichiometry RhCl(L)(COD).

Structure

The molecule consists of a pair of square planar Rh centers bound to a 1,5-cyclooctadiene and two chloride ligands that are shared between the Rh centers. The Rh2Cl2 core is also approximately planar, [4] in contrast to the highly bent structure of cyclooctadiene iridium chloride dimer where the dihedral angle is 86°.

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Cyclooctadiene iridium chloride dimer is an organoiridium compound with the formula [Ir(μ2-Cl)(COD)]2, where COD is the diene 1,5-cyclooctadiene (C8H12). It is an orange-red 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. The solid is air-stable but its solutions degrade in air.

<span class="mw-page-title-main">Chlorobis(cyclooctene)rhodium dimer</span> Chemical compound

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Rhodium carbonyl chloride is an organorhodium compound with the formula Rh2Cl2(CO)4. It is a red-brown volatile solid that is soluble in nonpolar organic solvents. It is a precursor to other rhodium carbonyl complexes, some of which are useful in homogeneous catalysis.

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Bis(triphenylphosphine)rhodium carbonyl chloride is the organorhodium complex with the formula [RhCl(CO)(PPh3)2]. This complex of rhodium(I) is a bright yellow, air-stable solid. It is the Rh analogue of Vaska's complex, the corresponding iridium complex. With regards to its structure, the complex is square planar with mutually trans triphenylphosphine (PPh3) ligands. The complex is a versatile homogeneous catalyst.

<span class="mw-page-title-main">Cyclooctadiene iridium methoxide dimer</span> Chemical compound

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References

  1. 1 2 Giordano, G.; Crabtree, R. H. "Di-μ-chloro-bis(η4-1,5-cyclooctadiene)dirhodium(I)" Inorganic Syntheses, 1990, volume 28, pages 88-90. doi : 10.1002/9780470132593.ch22
  2. Chatt, J.; Venanzi, L. M. (1956). "Olefin Complexes of Rhodium". Nature. 177 (4514): 852–3. Bibcode:1956Natur.177..852C. doi:10.1038/177852b0. S2CID   4296682.
  3. W. S. Knowles (2003). "Asymmetric Hydrogenations (Nobel Lecture 2001)". Advanced Synthesis & Catalysis. 345 (1–2): 3–13. doi:10.1002/adsc.200390028.
  4. "Di-μ-chloro-bis[(cis,cis-η4-1,5-cyclooctadiene)rhodium(I)]: a redetermination" De Ridder, Kirk J. A. Acta Crystallographica, Section C: Crystal Structure Communications 1994, C50, 1569-72. doi : 10.1107/S0108270194001459