1. The full vibrational spectra of the nido-carborane 11-CR3-2, 7-C2B9H12 and its μ-dideutero derivative were obtained. An assignment is proposed for some of the frequencies. 2. The Raman spectrum contained broad bands belonging to the stretching vibrations of the extra-hydrogens. Their frequencies lie at the high-frequency edge of the broad range which (according to published data) corresponds to the vibrations of the BHB bridging bonds. 3. It was found that the frequencies for the stretching vibrations of the outer σ bonds, starting from the atoms of the open face, are reduced in comparison with the analogous bonds in the closed part of the polyhedron. 4. Unlike icosahedral closo-carboranes, the nido-carborane 11-CH3-2,7-C2B9H12 does not form a plastic phase at 293°K but exists in the form of an ordered crystal.