Synthesis and reactivity of titanium 'POCOP' pincer complexes

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Pincer Ligand Development

Background:

• Pincer ligands are versatile scaffolds in coordination chemistry.
• Titanium complexes are crucial in various catalytic processes.
• The POCOP ligand offers unique steric and electronic properties.

Purpose of the Study:

• To synthesize and characterize novel titanium complexes featuring the POCOP pincer ligand.
• To explore the reactivity of these new titanium-POCOP complexes.
• To investigate the potential of POCOP ligands in early transition metal chemistry.

Main Methods:

• Lithium-halogen exchange for ligand synthesis.
• Reaction of POCOP ligand with Ti(III) and Ti(IV) precursors.
• Derivatization of titanium complexes with alkylating agents.
• Electron Paramagnetic Resonance (EPR) spectroscopy for characterization.
• Density Functional Theory (DFT) calculations for validation.

Main Results:

• First synthesis of titanium complexes with the POCOP pincer ligand in Ti(III) and Ti(IV) states.
• Observation of an unprecedented ligand rearrangement in the presence of Ti(IV).
• Synthesis of various alkylated titanium-POCOP complexes.
• Activation of H2 by a neopentyl complex, forming a rare titanium chlorohydride.
• EPR and DFT studies confirmed the characterization of paramagnetic species.

Conclusions:

• The POCOP ligand can be successfully incorporated into titanium complexes.
• These complexes exhibit novel reactivity, including H2 activation.
• This work expands the scope of pincer ligand applications to early transition metals.
• The findings open new avenues for designing titanium-based catalysts.