Remarkable Stereochemistry Control in the Polymerization of α‑Olefins Using a Simple Scandium Catalyst System
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A convenient approach to highly isotactic poly(α-olefin)s (mmmm > 99%) was realized using a simple scandium-based catalyst system consisting of ScCl3(THF)3, AliBu3, and [Ph3C][B(C6F5)4] under mild conditions. The resultant polymers possess ultrahigh molecular weight (Mn > 106) and relatively narrow molecular weight distribution. Especially, the excellent stereoselectivity still remains even at an elevated reaction temperature of 80 °C. Aluminum alkyls and organic borates, as well as their loadings significantly affected both the catalyst activity and product stereochemistry. The initial mechanistic exploration was carried out by means of NMR and ICP–AES spectroscopy, suggesting that a kind of incompact ion pair might be the active species. Further efforts to elucidate the real active sites and stereochemistry control mechanism of the catalytic system are underway.
