Chemistry:Dicobalt hexacarbonyl acetylene complex
(CO)6.svg)
Dicobalt hexacarbonyl acetylene complexes are a family of In organocobalt compounds with the formula Co
2(C
2R
2)(CO)
6. A large variety of R groups are tolerated. They are red compounds that are soluble in organic solvents. They arise from the reaction of alkynes and dicobalt octacarbonyl:[1]
- Co
2(CO)
8 + R
2C
2 → (R
2C
2)Co
2(CO)
6 + 2 CO
According to X-ray crystallography, the two Co atoms and two alkyne carbons form the vertices of a distorted tetrahedron. The C-C distance for the bridging alkyne ligand is 1.33 Å, and the Co-Co distance is 2.47 Å. The (R
2C
2)Co
2(CO)
6 core has C2v symmetry.[2] The structure is related to that of methylidynetricobaltnonacarbonyl and tetracobalt dodecacarbonyl, which are also tetrahedranes.
These complexes are intermediates in the Pauson-Khand reaction.
References
- ↑ Greenfield, Harold; Sternberg, Heinz W.; Friedel, Robert A.; Wotiz, John H.; Markby, Raymond; Wender, Irving (1956). "Acetylenic Dicobalt Hexacarbonyls. Organometallic Compounds Derived from Alkynes and Dicobalt Octacarbonyl1,2". Journal of the American Chemical Society 78: 120–124. doi:10.1021/ja01582a036.
- ↑ d'Agostino, Michael F.; Frampton, Christopher S.; McGlinchey, Michael J. (1990). "Diastereoselective Ligand and Vertex Substitutions in Bimetallic Bridged Alkyne Clusters: X-Ray Crystal Structure of .mu.2-(endo-2-Propynylborneol)hexacarbonyldicobalt". Organometallics 9 (11): 2972–2984. doi:10.1021/om00161a029.
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