Titanium complexes with unsymmetrically substituted imidazolin-2-iminato ligands

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Synthetic Chemistry

Background:

• N-heterocyclic carbenes (NHCs) are versatile ligands in organometallic chemistry.
• Unsymmetrical NHCs offer unique steric and electronic properties for complexation.
• Titanium(IV) complexes are important in catalysis and materials science.

Purpose of the Study:

• To synthesize and characterize novel titanium(IV) complexes featuring unsymmetrical N-heterocyclic carbene-derived ligands.
• To explore the reactivity of N-heterocyclic carbenes with trimethylsilyl azide and subsequent metalation with titanium precursors.
• To investigate the structural diversity of the resulting titanium complexes.

Main Methods:

• Reaction of N-heterocyclic carbenes (IAdMes and IAdDipp) with trimethylsilyl azide.
• Desilylation to form imidazolin-2-imines.
• Complexation with titanium(IV) precursors ([TiCl4(THF)2] and [CpTiCl3]).
• X-ray diffraction analysis for structural determination.

Main Results:

• Successful synthesis of 2-(trimethylsilylimino)imidazolines (2a, 2b) and imidazolin-2-imines (3a, 3b).
• Formation of mono- and bis(imidazolin-2-iminato) titanium(IV) complexes (4, 5, 6).
• Crystal structures of compounds 2a, 3a, 4, 5, and 6 were determined, revealing diverse coordination modes.

Conclusions:

• Unsymmetrical N-heterocyclic carbenes can be readily converted to imidazolin-2-imine ligands.
• These ligands form stable mono- and bis-complexes with titanium(IV).
• The structural characterization provides insights into the coordination chemistry of these novel complexes.