Flavone complexes of Ti and Zr active in ethylene polymerization

• Synthesis and characterization of two new Ti and Zr flavonoid complexes.
• The ligands come from natural and renewable sources.
• Those two complexes can be applied as catalysts for olefin polymerization.
• A complete electrochemical study of the new complexes was done and related with their catalytic ability in olefin polymerization.
• A theoretical study of the possible isomers and its energies was also performed.

Two new complexes of Ti and Zr were synthesized with 3-hydroxyflavone bidentate ligand and investigated in homogeneous ethylene polymerization. Both complexes were characterized by UV–VIS, 1H and 13C NMR, and electrochemical studies. The geometries and energies of all possible isomeric species were studied by full unconstrained optimizations performed at Density Functional Theory (DFT) level. The polymerization reactions were performed at different experimental conditions with methylaluminoxane (MAO), as the cocatalyst. Both complexes were active in ethylene polymerization in all the conditions used. However, zirconium complex showed the best activity comparing to the titanium complex at 2500 Al/M ratio. The polymers obtained were high density polyethylene with ultra high molecular weights.

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