Dicobalt hexacarbonyl acetylene complex explained

Dicobalt hexacarbonyl acetylene complexes are a family of In organocobalt compounds with the formula . 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]

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 core has C_2v 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

1. 10.1021/ja01582a036. Acetylenic Dicobalt Hexacarbonyls. Organometallic Compounds Derived from Alkynes and Dicobalt Octacarbonyl1,2 . 1956 . Greenfield . Harold . Sternberg . Heinz W. . Friedel . Robert A. . Wotiz . John H. . Markby . Raymond . Wender . Irving . Journal of the American Chemical Society . 78 . 120–124.
2. 10.1021/om00161a029. Diastereoselective Ligand and Vertex Substitutions in Bimetallic Bridged Alkyne Clusters: X-Ray Crystal Structure of .mu.2-(endo-2-Propynylborneol)hexacarbonyldicobalt . 1990 . d'Agostino . Michael F. . Frampton . Christopher S. . McGlinchey . Michael J. . Organometallics . 9 . 11 . 2972–2984 .