Preparation of half-metallocenes of thiophene-fused and tetrahydroquinoline-linked cyclopentadienyl ligands for ethylene/α-olefincopolymerization

Abstract

Directed ortho-lithiation of the lithium carbamates generated from tetrahydroquinoline or tetrahydroquinaldine enables one-step preparation of thiophene-fused and tetrahydroquinoline-linked cyclopentadienes [2-R¹-3-R²-4,5-dimethyl-6-(2-R³-2,3,4,5-tetrahydroquinolin-8-yl)-4H-cyclopenta[b]thiophene (R¹, R², R³ = H or methyl)], from which titanium(IV) and zirconium(IV) complexes are prepared. The molecular structures of Me₂Ti-complexes (12, R¹ = R² = Me, R³ = H; 14, R¹ = R² = R³ = Me) and Cl₂Zr-complex (17, R¹ = R² = Me, R³ = H) are determined by X-ray crystallography. The Me₂Ti-complexes, 14 and 15 (R¹ = R³ = Me, R² = H) show excellent activities (62 and 54 × 10⁶ g/molTi·h) in ethylene/1-octene copolymerization, even when activated with small amount of MAO (Al/Ti = 1000).