Acetyl-hydroxy-fulvene: A new ligand for chromium-catalyzed polymerization of ethylene at room temperature. Crystal structures of the ligands and chromium complex

• Acetyl-hydroxy-fulvenes as new ligand for chromium-catalyzed olefine polymerization.
• Molecular structures of an active chromium catalyst and corresponding ligands are reported.
• A fast screening method was used to test these ligands and a large variety of metal salts.
• Only the deprotonated form of the acetyl-hydroxy-fulvene ligands is able to generate a selective polymerization catalyst.

In the field of transition metal catalysts for olefin polymerization, the discovery of new chelating ligands has attracted significant interest. This paper reports on the polymerization of ethylene with new chromium based catalysts containing an acetyl-hydroxy-fulvene ligand. A parallel method was applied to screen eleven metal salts versus two different functionalized fulvene ligands. A direct visual analysis showed solid PE formation only in vials containing a chromium salt after 1 h of polymerization at 35 °C and 15 bar. This preliminary screening was followed by optimization studies to obtain high activities (up to 5 tPE/(mol·h)). ORTEP structures of the corresponding ligands and of the best catalysts were reported.

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