Hexadecacarbonylhexarhodium

Hexadecacarbonylhexarhodium

Names
IUPAC name Hexadecacarbonylhexarhodium
Other names Hexarhodium hexadecacarbonyl
Identifiers
CAS Number	28407-51-4
Properties
Chemical formula	C16O16Rh6
Molar mass	1065.62 g/mol
Appearance	Black crystals
Melting point	235 °C (455 °F; 508 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Hexadecacarbonylhexarhodium is a metal carbonyl cluster with the formula Rh₆(CO)₁₆.^[1] It exists as black crystals that are soluble in organic solvents.^[2]

Discovery and synthesis

Rh₆(CO)₁₆ was first prepared by Heiber in 1943 by carbonylation of RhCl₃·3H₂O at 80-230 °C and 200 atm carbon monoxide with silver or copper as a halide acceptor. It was incorrectly formulated as Rh₄(CO)₁₁. Subsequently, the carbonylation of a mixture of anhydrous rhodium trichloride and iron pentacarbonyl was shown to give good yields of Rh₆(CO)₁₆. Other compounds of rhodium are also effective precursors such as Rh₂Cl₂(CO)₄ and rhodium(II) acetate:^[3]

3 Rh₂(O₂CCH₃)₄ + 22 CO + 6 H₂O → Rh₆(CO)₁₆ + 6 CO₂ + 12 CH₃CO₂H

3 Rh₂Cl₂(CO)₄ + 4 CO + 6 Cu → Rh₆(CO)₁₆ + 6 CuCl

Reactions and applications

Rh₆(CO)₁₆ catalyzes a number of organic reactions including hydrogenation and hydroformylation.^[2]

References

1. Eugene R. Corey, Lawrence F. Dahl, Wolfgang Beck (1963). "Rh6(CO)16 and its Identity with Previously Reported Rh4(CO)11". J. Am. Chem. Soc. 85 (8): 1202–1203. doi:10.1021/ja00891a040.
2. Booth, B.L.; Else, M.J.; Fields, R.; Goldwhite, H.; Haszeldine, R.N. (1968). "Metal carbonyl chemistry IV. The preparation of cobalt and rhodium carbonyls by reductive carbonylation with pentacarbonyliron". Journal of Organometallic Chemistry 14 (2): 417. doi:10.1016/S0022-328X(00)87682-2.
3. B.R. James, G. L. Rempel and W.K. Teo (1976). "Hexadecacarbonylhexarhodium". Inorganic Syntheses. Inorganic Syntheses 16 (49): 49. doi:10.1002/9780470132470.ch15. ISBN 9780470132470.