Coordination and Reactivity Study of Titanium and Zirconium Complexes of the First Imidazol-2-imine Ethenolate Ligand

The synthesis and structural characterization
of group 4 transition
metal complexes bearing a novel imidazol-2-imine enolate ligand with
different electronic properties are reported. X-ray crystallographic
studies of a cyclopentadienyl zirconium complex confirmed the coordination
motif of the ligand through the imine nitrogen and ethenolate oxygen
atoms, yielding a new class of formally four-electron-donor monoanionic
bidentate ligands. The activities of the corresponding titanium­(IV)
and zirconium­(IV) complexes in ethylene polymerization were assessed,
resulting in activities up to 170 kg PE mol–1 h–1.