Rhodium carbonyl chloride

Rhodium carbonyl chloride
Identifiers
Properties
C4O4Cl2Rh2
Molar mass 388.76
Appearance red brown volatile solid
Density 2.708 g/cm−3
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

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.

Structure

The molecule consists of two planar Rh(I) centers linked by two bridging chloride ligands and four CO ligands. X-ray crystallography shows that the two Rh(I) centers are square planar with the dihedral angle of 53° between the two RhCl2 planes. The metals are nonbonding.[1]

Synthesis and reactions

First prepared by Walter Hieber,[2] it is typically prepared by treating hydrated rhodium trichloride with flowing carbon monoxide, according to this idealized redox equation:

2 RhCl3(H2O)3 + 6 CO → Rh2Cl2(CO)4 + 2 COCl2 + 6 H2O.[3]

The complex reacts with triphenylphosphine to give the bis(triphenylphosphine)rhodium carbonyl chloride:

Rh2Cl2(CO)4 + 4 PPh3 → 2 trans-RhCl(CO)(PPh3)2 + 2 CO

With chloride salts, the dichloride anion forms:

Rh2Cl2(CO)4 + 2 Cl− → 2 cis-[RhCl2(CO)2]−

With acetylacetone, rhodium carbonyl chloride reacts to give dicarbonyl(acetylacetonato)rhodium(I).

References

  1. ↑ Walz, Leonhard; Scheer, Peter "Structure of di-μ-chlorobis[dicarbonylrhodium(I)]" Acta Crystallographica Section C 1991, C47, 640-41. doi:10.1107/S0108270190009404
  2. ↑ Hieber, W.; Lagally, H. "Über Metallcarbonyle. XLV. Das Rhodium im System der Metallcarbonyle (Metal carbonyls. XLV. Rhodium in the system of metal carbonyls)" Zeitschrift für Anorganische und Allgemeine Chemie 1943, volume 251, pp. 96-113. doi:10.1002/zaac.19432510110
  3. ↑ McCleverty, J. A.; Wilkinson, G. "Dichlorotetracarbonyldirhodium (rhodium carbonyl chloride)" Inorganic Syntheses 1966, volume 8, pp. 211-14. doi:10.1002/9780470132463.ch4
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