Rearrangements in icosahedral boranes and carboranes revisited.

The structure, stability, and intermolecular rearrangements between ortho-, meta-, and para-C2B10H12 and were investigated using the hybrid density functional B3LYP/6-31G(d) for vibrational frequencies, as well as B3LYP/6-311+G(2d,p) for single-point electronic energies. The general trends in free energies of rearrangement between ortho-C2B10H12 to meta-C2B10H12 and meta-C2B10H12 to para-C2B10H12 presented here are consistent with experimental reaction temperatures. In addition, the majority of the rearrangements can be viewed in terms of concerted diamond-square-diamond steps and triangular face rotations.