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.