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Updated: Jan 13, 2026
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Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes
Published on: November 21, 2017
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Phenoxy-Amidine (FA) Titanium and Zirconium Complexes: Synthesis, Structure, and Use in Olefin Polymerization.
Thu-Van Nguyen1, Mehmet Jahja1, Jérôme Bayardon1
1Université Bourgogne Europe, CNRS, ICMUB UMR 6302, Dijon F-21000, France.
Inorganic Chemistry
|January 9, 2026
Summary
New titanium and zirconium bis(phenoxy-amidine) complexes were synthesized and tested for polymerization. These catalysts produced high-molecular-weight polyethylene with broad molecular weight distributions, indicating multisite behavior, while styrene polymerization showed single-site characteristics.
Area of Science:
- Organometallic Chemistry
- Polymer Chemistry
- Catalysis
Background:
- Bis(phenoxy-amidine) ligands offer tunable steric and electronic properties for metal complexation.
- Titanium and Zirconium complexes are widely investigated as catalysts for olefin polymerization.
Purpose of the Study:
- Synthesize and characterize novel bis(phenoxy-amidine) dichloro and bis(dimethylamido) titanium and zirconium complexes.
- Evaluate the catalytic activity of these complexes in ethylene and styrene polymerization.
- Investigate the influence of ligand substituents on polymerization performance and polymer properties.
Main Methods:
- Synthesis of bis(phenoxy-amidine) titanium and zirconium complexes.
- Solid-state structural analysis (X-ray diffraction).
- Solution state characterization (NMR spectroscopy).
- Catalytic polymerization of ethylene and styrene using methylaluminoxane (MAO) as a co-catalyst.
- Polymer characterization (molecular weight, molecular weight distribution, microstructure).
Main Results:
- Novel bis(phenoxy-amidine) Ti and Zr complexes [(FA)2MX2] were successfully synthesized.
- Solid-state structures exhibited distorted octahedral geometry with a specific O-trans, N-cis, X-cis configuration.
- Solution NMR studies revealed the presence of a single C2-symmetric isomer for all complexes.
- Ethylene polymerization yielded linear, ultra-high-molecular-weight polyethylene (Mw up to 2,154,000 g/mol) with broad molecular weight distributions (Mw/Mn = 14-408), indicating multisite catalysis.
- Complexes with tert-butyl substituents on the aryloxy ring demonstrated enhanced polymerization productivity (up to 230 kgPE/molcat/h).
- Styrene polymerization showed moderate activity (2-39 kgPS/molcat/h) producing atactic polystyrene with characteristics indicative of single-site behavior (Đ = 1.77-1.86).
Conclusions:
- The synthesized bis(phenoxy-amidine) Ti and Zr complexes are active catalysts for ethylene and styrene polymerization.
- Ethylene polymerization proceeds via a multisite mechanism, yielding high molecular weight polymers.
- Styrene polymerization exhibits single-site behavior, producing atactic polystyrene.
- Ligand design, specifically the incorporation of tert-butyl groups, can significantly enhance catalyst productivity.
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