Abstract: | The crystal structures of (Z)‐2‐methylbut‐1‐en‐1‐yl]4‐(trifluoromethyl)phenyl]iodonium trifluoromethanesulfonate, C12H13F3I+·CF3O3S?, (I), (3,5‐dichlorophenyl)(Z)‐2‐methylbut‐1‐en‐1‐yl]iodonium trifluoromethanesulfonate, C11H12Cl2I+·CF3O3S?, (II), and bis{3,5‐bis(trifluoromethyl)phenyl](Z)‐2‐methylbut‐1‐en‐1‐yl]iodonium} bis(trifluoromethanesulfonate) dichloromethane solvate, 2C13H12F6I+·2CF3O3S?·CH2Cl2, (III), are described. Neither simple acyclic β,β‐dialkyl‐substituted alkenyl(aryl)idonium salts nor a series containing electron‐deficient aryl rings have been described prior to this work. Compounds (I)–(III) were found to have distorted square‐planar geometries, with each I atom interacting with two trifluoromethanesulfonate counter‐ions. |