A Constraining and Redox-Active Aluminum Species With Diverse Reactivity

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Main-Group Chemistry

Background:

• Pincer ligands are crucial in stabilizing reactive metal centers.
• Aluminum complexes offer potential for novel reactivity but often face stability challenges.
• Redox-active ligands can enable cooperative effects in metal catalysis.

Purpose of the Study:

• To synthesize and characterize a novel aluminum complex with a sterically hindered, redox-active pincer ligand.
• To investigate the Lewis acidity and multifaceted reactivity of the aluminum complex.
• To explore the unique C-I bond activation mechanism and selectivity.

Main Methods:

• Synthesis and full characterization of the aluminum complex (2·Et2O).
• X-ray crystallography and spectroscopic methods for structural confirmation.
• Gutmann-Beckett studies and DFT calculations for Lewis acidity.
• Reactivity studies involving O-H bond activation, redox reactions, and C-I bond activation.

Main Results:

• The aluminum complex (2·Et2O) was successfully synthesized and characterized, revealing its molecular structure.
• Significant Lewis acidity was quantified, alongside diverse reactivity including photoinduced species formation and O-H bond activation.
• The complex selectively activated the C-I bond of iodoalkanes via a kinetically favored cooperative pathway, leading to ligand alkylation.

Conclusions:

• The synergy between the Al(III) center and the non-innocent pincer ligand enables unique reaction pathways.
• This work expands the scope of main-group elements in stoichiometric bond activation.
• The observed selectivity in C-I bond activation highlights the importance of metal-ligand cooperation.