Access to Ultra-High-Molecular Weight Poly(ethylene) and Activity Boost in the Presence of Cyclopentene With Group 4 Bis-Amido Complexes.

Zr complexes of the type [Me Si{(NR)(6-{2-(diethylboryl)phenyl}pyridyl-2-yl-N)}ZrCl ⋅thf] (R=tBu (4), adamantyl (7 a); thf=tetrahydrofuran), [Me Si{(NAd)(6-{2-(diphenylboryl)phenyl}pyridyl-2-yl-N)}ZrCl ] (Ad=adamantyl (7 b)), the nonbridged half-titanocene complexes of the type [(N-{6-(2-diethylborylphenyl)pyrid-2-yl}-NR)Cp'TiCl ] (R=Me, Cp'=C H (12), Cp'=C Me (13)), and the titanium(IV)-based metallocene-type complex [bis{N-(6-{2-(diethylboryl)phenyl}pyrid-2-yl)NMe}TiCl ] (14) have been synthesized. The structures of complexes 7 b, 12, and 13 were determined by single-crystal X-ray diffraction analysis. In solution, complex 4 slowly rearranges to [Me Si{(N-tBu)(6-{2-(diethylboryl)phenyl}pyridyl-2-yl-N)} Zr] (4 a), the structure of which was unambiguously confirmed by single-crystal X-ray crystallography.