Séminaire Dr Youngsuk KIM

Dr Youngsuk KIM

Department of Chemistry, Pusan National University, South Korea
E-mail: youngsuk.kim@pusan.ac.kr

Carbene-Derived Sulfur-Based Radicals and Their Applications

Singlet carbenes are well-known for their ability to stabilize various main-group radicals; however, carbene-derived, sulfur-based radicals remain rare. In this presentation, I will highlight two advances in carbene-stabilized sulfur radical chemistry. First, I will report the synthesis and characterization of novel diradical complexes featuring sulfur-based radical ligands derived from carbene–CS₂ adducts. These complexes exhibit an open-shell singlet ground state, confirmed through spectroscopic analysis, computational studies, and proton NMR relaxometry, with the unpaired electrons antiferromagnetically coupled on each ligand. The complexes display ligand-centered redox behavior, demonstrating the redox-active nature of these sulfur-based radical ligands. Second, I will introduce a new class of stable sulfide radical cations. Sulfide radical cations have recently garnered significant attention as key intermediates in both organic synthesis and in biological electron transfer processes. We have successfully synthesized exceptionally stable sulfide radical cations supported by two cyclic (alkyl)(amino)carbene moieties. These radical cations, characterized through EPR spectroscopy, X-ray crystallography, and DFT calculations, show remarkable stability to air, water, various chemical reagents, and elevated temperatures. Overall, this work not only establishes a new class of stable sulfur-based radicals but also demonstrates how strategic molecular design can enhance the stability of inherently reactive species.