Abstract
Stereospecific polymerization of propene by single-site catalysts is no longer limited to metallocenes. In the last few years, several non-metallocene catalysts have been shown to afford stereoregular polypropylenes, in addition to the classical syndiospecific V-based catalysts disclosed by Natta and Zambelli in the early 1960s. Recently, Coates reported the unexpected production of syndiotactic polypropylene by octahedral C sub 2 -symmetric titanium catalysts belonging to a class of bis(phenoxyimine) complexes developed by Fujita and coworkers (see Scheme 1). In this paper the stereochemical mechanism of syndiospecific polymerization of propene promoted by the latter catalysts is discussed on the basis of both experimental and theoretical results.