The geometries of the title compounds have been optimized at the levels of restricted Hartree-Fock (RHF) theory, second-order Moller-Plesset perturbation theory, and gradient-corrected density functional theory (DFT) using all-electron and effective core potential wave functions in conjunction with polarized double- and triple-zeta basis sets. The harmonic force fields have been determined from RHF and DFT calculations. The DFT results are generally in very good agreement with the available experimental data. The computed frequencies are accurate enough to be of predictive value, especially when correcting for small systematic errors. Several new assignments of bands in the observed vibrational spectra are proposed. Infrared intensities, dipole moments, and charge distributions are also discussed.