A new method for preparation and crystal structure of (trifluoromethyl)iodine dichloride

(Trifluoromethyl)iodine dichloride (CF3ICl2) is synthesized by the reaction of (trifluoromethyl)iodine chloride fluoride (CF3I(Cl)F) with trimethylchlorosilane ((CH3)(3)SiCl) at -40 degrees C. By using this route of preparation, in which CF3I(CI)F undergoes a chlorine-fluorine exchange, CF3ICl2 can be obtained in high purity and yield. CF3ICl2 crystallizes in the orthorhombic space group Cmca with a = 6.990(1) Angstrom, b = 7.985(1) Angstrom, c = 21.177(1) Angstrom, and eight formula units per unit cell. The final R indices [I > 2 sigma(I)] are R-1 = 0.0341 and wR(2) = 0.0631. CF3ICl2 is, in contrast to iodine trichloride (ICl3), monomeric, and its molecular structure is T-shaped with the CF3 group in the equatorial position. The Raman, IR, and NMR spectra are also described.