Appearance red brown volatile solid | ||
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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.
Contents
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.
Synthesis and reactions
First prepared by Walter Hieber, 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.The complex reacts with triphenylphosphine to give the monocarbonyl:
Rh2Cl2(CO)4 + 4 PPh3 → 2 trans-RhCl(CO)(PPh3)2 + 2 COWith chloride salts, the dichloride is formed:
Rh2Cl2(CO)4 + 2 Cl− → 2 cis-[RhCl2(CO)2]−