Iodine(III) CF3 reagents, commonly referred to as “Togni reagents”, attracted considerable attention not only as efficient electrophilic trifluoromethylating agents but also in the context of structure and bonding in main-group element compounds.1 Herein we present isolobal organotellurium compounds obtained by a formal replacement of the iodine by a tellurium atom. Tellurium(II)2 as well as tellurium(IV)3 derivatives were obtained on gram scale and structurally characterized by multinuclear NMR and single crystal X-ray diffraction. In the case of tellurium(II) compounds, two major synthetic approaches allowing the installation the CF3 (or RF) group on the tellurium atom were developed, by the use of electrophilic CF3I or nucleophilic TMSCF3 (or TMSRF), respectively. Factors determining the 125Te NMR chemical shifts of these compounds were studied by density functional theory (DFT).4 The analysis indicated that the variation in 125Te chemical shifts is mainly due to the magnetic coupling of the tellurium p-character lone pair with antibonding orbitals perpendicular to it upon action of an external magnetic field. Tellurium(IV) compounds were obtained in a three step sequence starting from a thermally induced reaction between an iodine(III) reagent and a ditelluride. The products are bench stable solids, however splitting of the CF3 group to a fluoride and difluorocarbene was observed upon heating in solution.
1. J. Charpentier, N. Früh, A. Togni, Chem. Rev. 2015, 115, 650–682.
2. E. Pietrasiak, A. Togni, Organometallics 2017, 36, 3750–3757.
3. E. Pietrasiak, A. F. Baxter, B. Jelier, N. Santschi, A. Togni, Helv. Chim. Acta 2019, 102, e1900079.
4. A. Togni, C. Coperet, E. Pietrasiak, C. P. Gordon, Phys. Chem. Chem. Phys. 2020, 22, 2319-2326.