Synthesis, Characterization, and Polymerization of a Neutral Tantalacarborane Sandwich Complex Derived from a Pentaanionic Exo-Polyhedrally Linked Bis(C2B10-carborane) Ligand

Tetramethyldisilazane-bridged closo-carborane compounds, [(closo-1-R-1,2-C2B10H10)Me2Si]2NH (R = Me (1), Ph (2)), and their tantalum complexes, [(closo-2-R-2,3-C2B10H10)Me2Si]2N]Ta(V) (R = Me (3), Ph (4)), have been prepared and characterized. Compounds 3 and 4 were found to be active catalysts for the polymerization of ethylene in the presence of the cocatalyst MAO to produce two morphologically different polyethylenes with high molecular weight.