New carbene and vinylidene chelate complexes of cyclopentadienylcobalt bearing a phosphorus tether

The {eta (5)[2-(di-tert-butylphosphanyl-P)ethyl]cyclopentadienyl} cobalt chelate was treated with trimethylsilylethyne to give the corresponding alkyne complex along with the trimethylsilylvinylidene complex. In a similar way, the bis(trimethylsilyl)ethyne complex was obtained. Silyl migration to give the bis(trimethylsilyl)vinylidene complex was observed at elevated temperature and represents the first cobalt example of this reaction. As the first cobalt vinylidene complex the bis(trimethylsilyl)vinylidene complex was characterized by an X-ray structure analysis. Reaction of the cobalt chelate with an Arduengo type carbene unexpectedly gave a non-chelated cobalt complex bearing the carbene ligand and ethene at the same metal atom. This complex was also structurally characterized. (C) 2001 Elsevier Science B.V. All rights reserved.