Dicarbollide Analogues of the Constrained-Geometry Polymerization Catalyst

A new type of constrained-geometry complex, [η 5:η 1 -RC 2 B 9 H 9 −CH 2 NMe 2 ]TiCl 2 ( 3 ), based on the dimethylamino dicarbollyl ligand has been prepared and characterized by 11 B, 13 C, and 1 H 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.