Tunneling of three borons in a B12 cluster

We report a theoretical investigation on a B12 cluster, which can exhibit a through ring umbrella inversion. Our calculations show that a part of the molecule consisting of a three membered boron ring can invert through the rest, viz., a nine membered boron ring. Using a simple model we calculate the double well potential for the motion. The barrier for inversion is found to be 4.31 kcal/mol. The vibrational levels and tunneling splitting are calculated using this potential. We find that the vibrational excitation to the v = 17 level will cause large amplitude “inversion oscillation” of the molecule. After including the tunneling effect, inversion rate at 298 K is calculated using transition state theory and is found to be 1.17 × 1010/s.