2-Hetaryl-Substituted Bis(indenyl)zirconium Complexes as Catalyst Precursors for Elastomeric Polypropylene Formation

Abstract

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. Deprotonation with n-butyllithium followed by transmetalation to zirconium gave the bis(2-furylindenyl)ZrCl2 complex 4a. Subsequent reaction with methyllithium yielded the corresponding bis(2-furylindenyl)ZrMe2 system 6a. The related bis[2-(5‘-methyl-2‘-furyl)indenyl]hafnium complexes (5a, 7a) and the bis[2-(5‘-methyl-2‘-thienyl)indenyl]zirconium and -hafnium complexes 4b−6b were synthesized analogously. In the crystal the bis(2-furylindenyl)ZrCl2 (4a) and -HfCl2 (5a) complexes exhibit meso-like metallocene conformations, as shown by X-ray diffraction. In contrast, the bis(2-furylindenyl)ZrMe2 system (6a) shows a chiral, close to C2-symmetric rac-like metallocene conformation in the solid state. Hydrolysis of 2-(5‘-methyl-2‘-furyl)indene (2a) followed by Paal−Knorr pyrrole synthesis of the resulting 1,4-diketone 8 with methylamine gave (5‘-methyl-2‘-N-methylpyrro...