2-hetaryl-substituted bis(indenyl)zirconium complexes as catalyst precursors for elastomeric polypropylene formation

2-Indanone was treated with 2-lithio-5-methylfuran and the addition product dehydrated to yield the 2-(5'-methyl-2'-furyl)-substituted indene 2. Depro tonation with n-butyllithium followed by transmetalation to zirconium gave the bis(2-furylindenyl)ZrCl2 complex 4a. Sub sequent reaction with methylli thium yielded the corresponding bis(8-furylindenyl)ZrMe2 system 6a. The rel ated bis[2-(5'-methyl-2'-furyl)indenyl]hafnium complexes (5a, 7a) and the b is[2-(5'-methyl-2'-thienyl)indenyl]zirconium and -hafnium complexes 4b-6b w ere synthesized analogously. In the crystal the bis(2-furylindenyl)ZrCl2 (4 a) and -HfCl2 (5a) complexes exhibit meso-like metallocene conformations, a s shown by X-ray diffraction. In contrast, the bis(2-furylindenyl)ZrMe2 sys tem (6a) shows a chiral, close to Ca-symmetric rac-like metallocene conform ation in the solid state. Hydrolysis of 2-(5'-methyl-2'-furyl)indene (2a) f ollowed by Paal-Knorr pyrrole synthesis of the resulting 1,4-diketone 8 wit h methylamine gave (5'-methyl-2'-N-methylpyrrolyl)indene (9), which was dep rotonated and transmetalated to yield the substituted bis(2-pyrrolylindenyl )ZrCl2 (11), -HfCl2 (12), and -ZrMe2 (13) complexes. Treatment of the [2-(5 '-methyl-2'-furyl)indenyl]- and [2-(5'-methyl-2'-thienyl)indenyl]ZrCl2 syst ems 4a,b with excess methylalumoxane gave active homogeneous Ziegler cataly sts for the production of elastomeric polypropylene. The catalyst derived f rom 11 yielded only propene oligomers.