Chemistry:Cyclopentadienylmolybdenum tricarbonyl dimer

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Cyclopentadienylmolybdenum tricarbonyl dimer
IUPAC name
Other names
cyclopentadienyl molybdenum carbonyl dimer
3D model (JSmol)
EC Number
  • 235-156-0
Molar mass 489.96 g/mol
Appearance dark red crystalline solid
Melting point 222 °C (432 °F; 495 K)
Boiling point dec.
0.112 D
Main hazards flammable
GHS pictograms GHS06: ToxicGHS07: Harmful
GHS Signal word Danger
H302, H312, H332
Related compounds
Related compounds
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

Cyclopentadienylmolybdenum tricarbonyl dimer is the chemical compound with the formula Cp2Mo2(CO)6, where Cp is C5H5. A dark red solid, it has been the subject of much research although it has no practical uses.

Structure and synthesis

The molecule exists in two rotamers, gauche and anti.[1] The six CO ligands are terminal and the Mo-Mo bond distance is 3.2325 Å.[2] The compound is prepared by treatment of molybdenum hexacarbonyl with sodium cyclopentadienide followed by oxidation of the resulting NaMo(CO)3(C5H5).[3] Other methods have been developed starting with Mo(CO)3(CH3CN)3 instead of Mo(CO)6.[4]


Thermolysis of this compound in hot solution of diglyme (bis(2-methoxyethyl)ether) results in decarbonylation, giving the tetracarbonyl,[4] which has a formal triple bond between the Mo centers (dMoMo = 2.448 Å):[5]

(C5H5)2Mo2(CO)6 → (C5H5)2Mo2(CO)4 + 2 CO

The resulting cyclopentadienylmolybdenum dicarbonyl dimer in turn binds a variety of substrates across the metal-metal triple bond.

Related compounds


  1. Brian Mann (1997-01-06). "Fluxionality of Cp2Mo2(CO)6". University of Sheffield. 
  2. R. D. Adams, D. M. Collins, and F. A. Cotton (1974). "Molecular Structures and Barriers to Internal Rotation in Bis(η5-cyclopentadienyl)hexacarbonylditungsten and Its Molybdenum Analog". Inorg. Chem. 13 (5): 1086–1090. doi:10.1021/ic50135a015. 
  3. Manning, A. R.; Hacket, Paul; Birdwhistell, Ralph (1990). "Hexacarbonylbis(η5-Cyclopentadienyl)Dichromium, Molybdenum, and Tungsten and their Analogs, M25-C5H4R)2(CO)6 (M = Cr, Mo, and W; R = H, Me or PhCH2)". Inorganic Syntheses 28: 148–149. doi:10.1002/9780470132593.ch39. 
  4. 4.0 4.1 Curtis, M. David; Hay, Michael S. (1990). "Cyclopentadienyl Metal Carbonyl Dimers of Molybdenum and Tungsten". Inorganic Syntheses 28: 150–152. doi:10.1002/9780470132593.ch40. 
  5. Cotton, F. A.; Walton, R. A. "Multiple Bonds Between Metal Atoms" Oxford (Oxford): 1993, p 564ff. ISBN:0-19-855649-7.