Dicarbollide Analogues of the Constrained-Geometry Polymerization Catalyst

A new type of constrained-geometry complex, [η5:η1-RC2B9H9−CH2NMe2]TiCl2 (3), based on the dimethylamino dicarbollyl ligand has been prepared and characterized by 11B, 13C, and 1H NMR spectroscopy. This complex is the first example of a compound containing the “CGC-type” dicarbollyl ligand for titanium in its highest (4+) oxidation state. Complexes 3 in the presence of MMAO exhibit moderate catalytic activities for the ethylene polymerization but produce high-molecular-weight polymers.