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

Abstract

In the reaction of the decamethylzirconocene-bis(trimethylsilyl)acetylene complex Cp* 2 Zr(η 2 -Me 3 -SiC 2 SiMe 3 ) (1) with i-Bu 2 AlH, CH bond activation, an electrophilic substitution, and alumination of the pentamethylcyclopentadienyl ligand resulted in formation of the η 5 -C 5 Me 4 CH 2 -Al(i-Bu) 2 H ligand. The final product contains an alkenyl complex that shows an agostic C-H···Zr interaction, Cp*Zr[-C(SiMe 3 )= CH(SiMe3)](μ-H)[η 5 -C5Me4CH2-Al(ι-Bu) 2 ] (2). Heating complex 2 gives the heterobimetallic complex Cp*Zr[-C(SiMe3)=C(SiMe3)Al(i-Bu)(μ-H)(CH 2 -η 5 -C5Me4)] (3), which is formed by an intramolecular reaction, analogous to intermolecular reactions of titanocene- and zirconocene-alkyne complexes with i-Bu 2 AlH, 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 e-caprolactone.