Preparation and reactions of monocyclic bis(cyclopentadienyl)titanacyclopentenes and -pentadienes

A combination of CP2TiCl2-2EtMgBr was found to be very effective for the formation of monocyclic titanacyclopentenes in excellent yields. On the other hand, a combination of Cp2TiCl2-2n-BuLi was used for intermolecular coupling of two alkynes to form titanacyclopentadienes in good to excellent yields. A reaction temperature range from -10 to -30 degreesC was critical for the success of the combinations. Reactions of these in situ-prepared titanacycles show interesting similarities to or differences from their zirconacycle analogs. (C) 2001 Published by Elsevier Science BN.Chemistry, Inorganic & NuclearChemistry, OrganicSCI(E)19ARTICLE1-218-2663