Activation of Metallacyclopropenes,five-membered Metallacyclocumulenes and Metallacyclopentynes of Zirconium with iBu2AlH

The recently described reaction products of zirconacyclopropenes Cp^′₂Zr(η²-Me₃SiC₂SiMe₃) and five-membered zirconacyclocumulenes (zirconacyclopenta-2,3,4-trienes) Cp*₂Zr(η⁴-1,2,3,4-RC₄R), Cp* = η⁵-pentamethylcyclopentadienyl, R = Me, Me₃Si and Ph, with i-Bu₂AlH are active catalysts in the polymerization of ethylene and in the ring opening polymerization of ε-caprolactone. Here we describe the different activity of these complexes after thermal activation or if additional i-Bu₂AlH together with water are added. These results are compared to those which were obtained with the complexes Cp₂Zr(η⁴-1,2,3,4-H₂C₄H₂), rac-(EBTHI)ZrF₂, rac-(EBTHI)ZrCl₂, rac-(EBTHI)Zr(H)(µ-H)]₂ and rac (EBTHI)Zr(F)CH₂-CH₂(2-Py) after activation with i-Bu₂AlH together with water.