Cationic ligands - from monodentate to pincer systems

Area of Science:

• Coordination Chemistry
• Organometallic Chemistry
• Catalysis

Background:

• Cationic ligands were historically underrepresented in coordination chemistry.
• Recent years have seen a surge in interest and reporting of metal-coordinated cationic species.
• This growing interest is fueled by their significant catalytic potential.

Purpose of the Study:

• To provide a comprehensive review of cationic ligands featuring a pincer architecture.
• To analyze the electronic structure, donor/acceptor properties, and reactivity of these systems.
• To compare the properties of cationic pincer complexes with their neutral counterparts.

Main Methods:

• Review of existing literature on cationic pincer ligands.
• Analysis of electronic structure using computational studies (Density Functional Theory - DFT).
• Discussion of experimental data including Infrared (IR) spectroscopy, Nuclear Magnetic Resonance (NMR) spectroscopy, and Cyclic Voltammetry (CV).

Main Results:

• Cationic pincer ligands offer unique electronic and steric properties.
• The positive charge significantly influences spectroscopic and redox characteristics.
• These ligands enable novel reactivity patterns in metal complexes.
• Sulfonium-based pincer ligands represent a recent and promising development.

Conclusions:

• Pincer-stabilized cationic ligands are increasingly important in catalysis.
• Understanding their electronic and structural features is key to designing new catalysts.
• Further exploration of these systems, including sulfonium-based variants, promises significant advancements.