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 Rf 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.