Furthermore, the size of the chair isomer is approximately -16.83 au smaller than that of the boat isomer---as indicated by the electron extend <R 2 >, another feature contributing to its greater stability. The transition energy height is given by 4.1 kcal/mol Ref d The total electronic energy of exo-TCD-chair as -390.833732 Eh and exo-TCD-boat as -390.830822 Eh. The corresponding total energies are -390.473087 Eh and -390.4669991 Eh, respectively, using B3LYP/6-31G(d,p). e An early calculated dipole moment of exo-TCD using HF/6-311+G** was given by 0.06 Debye. which is close to the dipole moment of TS of 0.0597 Debye in this study.