KCS

We have recently demonstrated that nonbridged half-titanocenes, Cp’TiCl₂(X) (Cp’: cyclopentadienyl group, X: anionic donor ligands such as aryloxo, ketimide etc.) are promising catalyst precursors for precise synthesis of some new ethylene copolymers that can not be prepared ordinary metallocenes, linked (constrained geometry type) half-titanocenes.  In this lecture, I will introduce the basic catalyst design and our recent successful examples, especially ethylene copolymerizations (with cyclic olefins, sterically encumbered olefins).  Since precise and efficient synthesis of functionalized polyolefins by controlled polymerization attracts considerable attention, I will also introduce the following two approaches we recently established for the purpose: (1) precise introduction of polar functionality under mild conditions utilized by repeated insertion of nonconjugated diene, (2) direct introduction of SiR₃ functionalities by efficient ethylene copolymerizations.