β-Bis-CF3-substituted phosphorus corroles, theory and experiments

Abstract

16 bis-trifluoromethylated tpfc (5,10,15-tris(pentafluoro)corrole) phosphorus difluoride complexes were calculated; they were geometrically optimized and theoretically analyzed to help more completely understand the effect of multi-CF₃ substitution in porphyrinoids. Six such compounds were experimentally prepared via two different reaction pathways: (i) treating the non-substituted (tpfc)PF₂ and the mono-CF₃-subsituted 1b, respectively, with FSO₂CF₂CO₂Me and CuI yielded the previously reported compounds 1a–1d and the new bis-CF₃ substituted complexes 2b–2e; and (ii) photoinduced generation of another bis-CF₃ substituted species afforded 2f by using 1b as the starting material and dMeSCF₃ as the CF₃ source. The latter experimental pathway is, to the best of our knowledge, the first case of photocatalytic trifluoromethylation in porphyrin chemistry. Structural assignments of these newly prepared compounds were successfully achieved by the elaborate combination of experiments and calculations, which allowed compounds 2b–2f to be tentatively assigned as the Bis-2,3; Bis-2,17; Bis-3,13; Bis-7,12; and Bis-3,8 CF₃-substituted corroles. Interestingly, the assignments were further supported by comparing experimental R_f values with calculated dipole moments of each isomer. Experimental UV-vis and fluorescence spectra, as well as cyclic voltammetry data obtained for 2a–2f allowed us to uncover clear differences of photophysical and electrochemical redox properties that were correlated with data from TDDFT energy level analyses.