Resonance Raman (RR) and FT-IR spectra are reported for free-base tetraphenylbacteriochlorin and its pyrrole-N-15(4), beta-D-8, meso-C-13(4), and phenyl-D-20 isotopomers. A normal mode analysis is carried out in order to assign observed RR and IR modes, using a NiTPP-based force field, with bond-distance scaling of force constants and the introduction of long-range interaction constants. The modes correlate well with those of NiTPP, once due allowance is made for direct effects of pyrrole ring reduction : inequivalent C-beta-C-beta and C-alpha-C-beta bonds and extra C-beta-H bending modes. Although the C-alpha-C-m and C-alpha-N bonds of the 16-membered inner ring are not strictly equivalent, there is little tendency for mode localization with respect to these bonds. The absence of a central metal lowers the frequencies of C-alpha-C-m stretching and pyrrole translational modes. The RR enhancement pattern is quite different than for porphyrins. Totally symmetric modes dominate spectra in resonance with the Q(x) band, due to a larger transition moment than in porphyrins, while non-totally symmetric modes are strongly enhanced in the region of the close-lying B-x and B-y transitions, reflecting vibronic coupling between them.