The optimized structures of tert-butyl alcohol and tert-butyl alcohol/benzene (Tb-Tb and Tb-B) dimers were obtained by ab initio calculations at the HF/6-311++G(d,p) level, with electron correlation energy corrections using the local Moller-Plesset perturbation method. The small H-bond energies for these dimers are expected to be roughly overcome by the entropy change that accompanies the complexation reaction. Correlation times and temperature-dependent line width analysis of two selected benzene infrared bands in several liquid Tb-B mixtures indicate that there are marked mode-sensitive differences in the relaxation mechanisms taking place in solution. These are likely to be due to formation of Tb-B complexes similar to that predicted by gas-phase theoretical calculations.