C₂ -Symmetric Bissulfoximine-Based Metal Complexes: Synthesis, Characterization and Their Electrocatalytic Activity...

Area of Science:

• Organometallic Chemistry
• Catalysis
• Coordination Chemistry

Background:

• Sulfoximine compounds are gaining interest in synthetic organic chemistry and organometallics.
• The coordination chemistry of pincer sulfoximine ligands and their metal complexes remains largely unexplored.

Purpose of the Study:

• To synthesize and characterize novel C2-symmetric bissulfoximine-based pincer ligands and their metal complexes.
• To investigate the electrocatalytic activity of these metal complexes for the oxygen reduction reaction (ORR).

Main Methods:

• Synthesis of a C2-symmetric bissulfoximine-based pincer ligand (S-P ligand).
• Preparation and characterization of metal complexes [M(SP)2]2+ (M=Fe, Co, Ni, Cu) using spectroscopic techniques (UV-Vis, IR, NMR, ESI-MS) and single-crystal XRD.
• Electrocatalytic evaluation of immobilized complexes on glassy carbon electrodes for ORR.

Main Results:

• Complexes SC-1 (Fe) and SC-3 (Ni) displayed octahedral geometry.
• All synthesized metal complexes exhibited selective two-electron catalytic reduction of O2 to H2O2.
• Complex SC-2 (Co) achieved the highest selectivity (≈90%) for H2O2 production.
• Complex SC-4 (Cu) demonstrated the highest onset potential (0.75 V) for the ORR.

Conclusions:

• The study successfully synthesized and characterized novel pincer sulfoximine metal complexes.
• These complexes show potential as electrocatalysts for the selective reduction of oxygen to hydrogen peroxide.
• The findings open avenues for developing new catalysts for specific redox reactions.