Resonance Raman (RR) spectra are reported for the anion radical and for the photoexcited triplet state of ZnTPP. The anion radical was prepared by controlled-potential electrolysis in dry dimethylformamide, and care was taken to avoid phlorin contamination. RR spectra were obtained by excitation at 457.9 nm, at the anion absorption band maximum. Bands were assigned with the aid of pyrrole-d8 and phenyl-d20 isotopomers. The pattern of isotope shifts and polarizations was found to be quite similar to that of the neutral parent, ZnTPP, and meaningful mode correlations are possible: nu-2, nu-10, nu-27, and nu-29 shift down 15-20 cm-1 upon reduction, while nu-1, nu-4, and the phenyl mode phi-4 are essentially unaffected. This frequency shift pattern is discussed in terms of the expectations for placing an electron in the e(g)* orbital, including the anticipated Jahn-Teller (J-T) effect. Although band overlaps make depolarization ratios difficult to quantitate, the nu-10 band is found to be essentially depolarized, indicating that the J-T effect is dynamic, rather than static in character, at least with respect to stretching of the C-alpha-C(m) bonds. The nu-2 and nu-10 downshifts are attributable to porphyrin core expansion upon reduction, but the nu-27 and nu-29 reductions are probably manifestations of the J-T effect. Triplet-state RR spectra were produced with 416-nm photolysis and 459-nm probe pulses (7 ns) from electronically timed Q-switched Nd:YAG lasers equipped with H2/D2 Raman shifters. The RR peaks were assigned via their polarizations and the d8 and d20 isotopomer shifts. The spectrum contains three strong bands of predominantly phenyl character. Their frequencies are unshifted relative to the ground state, implying negligible electronic involvement of the phenyl groups in the T1 state, but their enhancements indicate substantial involvement in the resonant T(n) state. This state is suggested to be produced by charge transfer from the porphyrin e(g)* to the phenyl pi* orbitals. There are also four weak bands, which are assigned to the porphyrin skeletal modes nu-2, nu-10, nu-11, and nu-27. The first three of these are at frequencies which are 40-50 cm-1 lower than in the ground state. For nu-2 the shift is comparable to the sum of the shifts seen upon forming the ZnTPP cation radical and anion radical, but for nu-10 the shift is much larger than this sum, indicating that the J-T effect is more pronounced in the triplet state than in the radical anion. Consistent with this conclusion, the nu-10 band of 3ZnTPP is partially polarized, suggesting a static J-T distortion along the C-alpha-C(m) bonds. However, the nu-11 band is depolarized, implying that the C-beta-C-beta bonds remain equivalent. The nu-27 band shifts up 15 cm-1 and broadens significantly, suggesting a dynamic B2g J-T effect along the C(m)-phenyl bonds.
