Structure of (PhC CH)(3)Co-2(CO)(6): A new Co-2(CO)(8) catalyzed oligomerization sequence of an alkyne and carbon monoxide

Hubel's tris(ethynylbenzene)hexacarbonyldicobalt complex, (PhC=CH)(3)Co-2(C O)(6), a byproduct in cobaltacyclopentadiene formation, has been characteri zed by spectroscopic methods and a single-crystal X-ray diffraction analysi s. The organic ligand, derived from the ester [(1,2,3,4,5-eta)-2,5-diphenyl cyclopenta-2,4-dienyl][(2-eta)(3-eta:3-eta)]-2H-3-phenylpropynoate, forms a eta(1):eta(2)-bridge between the two cobalt atoms linked by a "semibridgin g" carbonyl.