N-Heterocyclic carbene-derived second-period main-group radicals: Synthesis, fundamentals, and applications

The stabilization of organic radicals has long been a challenge due to their intrinsic reactivity. N-Heterocyclic carbenes (NHCs), with their unique electronic and steric properties, have emerged as powerful tools for stabilizing persistent radicals. This review highlights the latest advancements in carbene-supported organic radicals, covering key structural motifs, electronic properties, and implications for chemical reactivity. We discuss recent breakthroughs in the design of radical species derived from NHCs, cyclic (alkyl)(amino)carbenes (CAACs), and diamidocarbenes (DACs). The relationships among radical stability, spin delocalization, and functional applications are systematically discussed, particularly in the context of redox-active materials, photocatalysis, and electronic devices. This work underscores the broader significance of NHC-stabilized radicals in fundamental chemistry and applied sciences, offering insights into future directions for the field.