Constrained geometry single-site catalysts have garnered significant academic and industrial interest over the past two decades.  Constrained geometry catalysts (CGC) are typically comprised of an ?5-cyclopentadienyl moiety tethered to a neutral or monoanionic donor.  The constrained angle at the metal that results from the additional donor leads to increased catalyst activity.  The majority of CGC complexes consist of a monoanionic or dianionic ligand bound to a group 3 or group 4 metal. Our goal was to develop trianionic CGC ligands in which a cyclopentadienyl moiety is tethered to a diindolylmethane or dipyrrolylmethane.   Pyrrole and indole were chosen as donors to reduce N?M pi-donation and increase Lewis acidity at the metal.  A concomitant increase in catalytic activity is anticipated.  Synthesis and characterization of several examples of this new class of ligands, along with representative group 4 and group 5 metal complexes will be presented.

New class of trianionic constrained geometry ligands:  Synthesis, characterization, and representative complexes

243rd National Meeting (2012)

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