Highly Fluorinated (σ-Aryl)-Chelating Titanium(IV) Post-Metallocene: Characterization and Scalar [C–H···F–C] Coupling

The observation of weak intramolecular C–H···F–C interactions in group 4 (σ-aryl)-chelating complexes using NMR spectroscopic and neutron diffraction studies was recently reported. In this work, a new titanium(IV) catalyst precursor supported by a tridentate pyridine-2-phenolate-6-(σ-aryl) ligand, featuring a metal center surrounded by multiple CF3 substituents, has been synthesized. The nature of intramolecular interactions in the bis(benzyl) complex in solution was probed using multinuclear NMR spectroscopic experiments (including [1H,19F]-HMQC and -HMBC), which reveal scalar coupling across C–H···F–C interactions between methylene hydrogens and the proximal CF3 group on the σ-aryl (but not the phenolate) moiety. High activities are observed for ethylene polymerization at different temperatures, which exceed those for the tBu-phenolate congener.

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