Trifluoromethyl Thianthrenium Salts: From Organic Synthesis to Materials

Trifluoromethyl thianthrenium salts have recently emerged as powerful and versatile reagents in organic chemistry, enabling the direct transfer of the CF₃ group under mild and operationally simple conditions. Its straightforward, scalable synthesis from inexpensive starting materials provides a practical alternative to classical Umemoto- and Togni-type reagents. Beyond its role as a trifluoromethylating agent, trifluoromethyl thianthrenium salts have unlocked new classes of reagents and innovative activation modes, ranging radical, photochemical, electrochemical, mechanochemical, and even magnetoredox processes. This unique versatility has expanded the synthetic toolbox for constructing fluorine-containing molecules of interest to pharmaceuticals, agrochemicals, and functional materials. Furthermore, recent breakthroughs demonstrate that trifluoromethyl thianthrenium salts extend beyond molecular synthesis into materials settings, enabling controlled functionalization and defect passivation of two-dimensional (2D) semiconductors, thereby bridging fundamental chemical reactivity with device-level applications. This Perspective highlights the synthesis, reactivity, and emerging applications of trifluoromethyl thianthrenium salts, emphasizing how these reagents exemplify the growing interface between fluorine chemistry, radical reactivity, and materials science.