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

Sulfoximine-based metal complexes have gained much interest in recent years owing to their promising properties in synthetic organic chemistry. These sulfoximines have been recently introduced in the field of organometallics. However, the coordination properties of pincer sulfoximine ligands and their metal complexes have not been reported. Here, a C2 -symmetric bissulfoximine-based pincer ligand ((pyridine-2,6-diylbis(methylene))bis(azaneylylidene))bis(diphenyl-λ6 -sulfanone), namely S-P ligand and its metal [M(SP)2 ]2+ {M=Fe (SC-1), Co (SC-2), Ni (SC-3), Cu (SC-4)} complexes, were synthesized. The complexes were characterized by different spectroscopic techniques like UV-Vis, IR, NMR, ESI-MS, and single-crystal XRD. Complexes SC-1 and SC-3 exhibited octahedral geometry irrespective of the metal center. The complexes were systematically explored for electrocatalytic oxygen reduction reaction (ORR) by immobilizing them on a glassy carbon electrode using Nafion. These complexes showed selective two-electron catalytic reduction of O2 to H2 O2 in which complex SC-2 showed the highest selectivity (≈90%) and complex SC-4 showed the highest onset potential (0.75 V).

Diversification of α-ketoamides via transamidation reactions with alkyl and benzyl amines at room temperature.

A wide range of N-tosyl α-ketoamides underwent transamidation with various alkyl amines in the absence of a catalyst, base, or additive. On the other hand, transamidation in N-Boc α-ketoamides was achieved in the presence of Cs2CO3. The reactions proceeded at room temperature and provided good to excellent yields of transamidation products under the optimized conditions. Broad substrate scope, functional group tolerance and quick conversions are the important features of the developed methodology.