Bis-hydroxylaminato group 4 half-sandwich complexes-syntheses, structures and polymerisation activity studies.

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Polymerization Catalysis

Background:

• Bis-hydroxylamines are versatile ligands in organometallic chemistry.
• Cp*MCl3 complexes (M = Ti, Zr, Hf) are important precursors for catalytic applications.

Purpose of the Study:

• To synthesize novel organometallic complexes using methylene- and ethylene-bridged bis-hydroxylamines.
• To investigate the coordination behavior of these ligands with Cp*Ti, Cp*Zr, and Cp*Hf complexes.
• To evaluate the catalytic activity of the synthesized complexes in olefin polymerization.

Main Methods:

• Reaction of bis-hydroxylamines with [Cp*TiCl3], [Cp*ZrCl3], and [Cp*HfCl3] in the presence of MeLi.
• Characterization using NMR spectroscopy, elemental analyses, and mass spectrometry.
• X-ray diffraction for crystal structure determination.
• Catalytic testing in ethylene and propylene polymerization using methylaluminoxane (MAO) activation.

Main Results:

• Synthesis of novel [Cp*MMe(ligand)] complexes (M = Ti, Zr, Hf).
• Structural elucidation revealing eta(2)-coordination of all four donor atoms of the bis-hydroxylamine ligands.
• Formation of an adduct with AlMe3.
• Successful activation of titanium complexes with MAO for olefin polymerization.

Conclusions:

• The bis-hydroxylamine ligands form stable eta(2)-coordinated complexes with Cp*Ti, Cp*Zr, and Cp*Hf fragments.
• The synthesized complexes, particularly titanium-based ones, demonstrate catalytic activity in ethylene and propylene polymerization when activated with MAO.