Crystal structure of ansa-Me2Si-(2Me-4-p-Tol-cyclopenta[b]indol-3-yl)2ZrCl2 and its catalytic properties in the polymerization of propylene

A new zirconocene ansa-Me₂Si-(2Me-4-p-Tol-cyclopentab]indol-3-yl)₂ZrCl₂ complex (I), in which the Cp ligand is fused with the indole ring, has been synthesized and studied by X-ray diffraction analysis. Light brown crystals are triclinic, space group P `1]\bar 1; M = 734.92, a = 9.252(2) ?, b = 12.914(3) ?, c = 15.619(3) ?, α = 111.83(3)°, β = 81.03(3)°, γ = 117.77(3)°, V = 1569(3) ?³, Z = 2, ρ_calc = 1.525 g/cm³. The structural parameters of complex I are compared with the known bis-indenyl zirconium complexes: rac-Me₂Si(Ind)₂ZrCl₂ (II) and rac-Me₂Si(2Me-2Ph-1-Ind)₂ZrCl₂ (III) and analogous substituted rac-Me₂Si(2,5-Me₂-3Ph-6-Cpb]Tp)₂ZrCl₂ (IV) and rac-Me₂Si(2,5-Me₂-1Ph-4-Cpb]Py)₂ZrCl₂ (V). Complex I alkylated by the Grignard reagent (MgMe₂) in the presence of the Al-iso-Bu₃ cocatalyst is an efficient catalyst for the polymerization of propylene into isotactic polypropylene.