Continuous wave and pulse EPR as a tool for the characterization of monocyclopentadienyl Ti(III) catalysts

Monocyclopentadienyl Ti(III) catalysts in which the cyclopentadienyl ring h as a heteroatom-functionalized side chain are used in the polymerization of olefins and the co-polymerization of ethylene with propylene, 1-hexene, 1- octene and styrene. In this work, we show that a combined continuous wave a nd pulse EPR study of such complexes can reveal structural information wher e other analytical methods fail. Hyperfine sublevel correlation (HYSCORE) s pectroscopy is found to be a powerful method to identify the type of nuclei surrounding the Ti3+ ion. For the first time. the hyperfine and nuclear qu adrupole data of Ti(III)-bound N-14 nuclei are reported. The observed value s are compared to known data of different transition metal complexes. Furth ermore, the observed proton and lithium interactions are discussed. (C) 200 1 Published by Elsevier Science B.V.