Simple Alumination Reactions of Pentamethylcyclopentadienyl Ligands in the Decamethylzirconocene−Bis(trimethylsilyl)acetylene Complex Cp*₂Zr(η²-Me₃SiC₂SiMe₃)

In the reaction of the decamethylzirconocene−bis(trimethylsilyl)acetylene complex Cp*2Zr(η2-Me3SiC2SiMe3) (1) with i-Bu2AlH, CH bond activation, an electrophilic substitution, and alumination of the pentamethylcyclopentadienyl ligand resulted in formation of the η5-C5Me4CH2−Al(i-Bu)2H ligand. The final product contains an alkenyl complex that shows an agostic C−H···Zr interaction, Cp*Zr[−C(SiMe3)CH(SiMe3)](μ-H)[η5-C5Me4CH2−Al(i-Bu)2] (2). Heating complex 2 gives the heterobimetallic complex Cp*Zr[−C(SiMe3)C(SiMe3)Al(i-Bu)(μ-H)(CH2−η5-C5Me4)] (3), which is formed by an intramolecular reaction, analogous to intermolecular reactions of titanocene- and zirconocene-alkyne complexes with i-Bu2AlH, which yield the well-known heterobimetallic complexes with tetracoordinated planar carbon atoms. Both complexes were characterized by NMR spectroscopy and X-ray crystal structure analysis. Complex 2 catalyzes the ethene polymerization and the ring-opening polymerization of ε-caprolactone.