The hybrid density-functional (B3LYP/6-31G(d, p)) method was used to understand why no 1,2-dimethyl dodecahedrane has been reported yet. From the direct dimethyl substitution of the dodecahedrane cage, we could have five C20H18(CH3)2 derivatives which were geometrically optimized without constraints. The results suggest that 1,16-dimethyl dodecahedrane derivative is the most stable, whereas the 1,2-dimethyl derivative is the most unstable; this implies that the distortion due to steric hinderance interactions would be a crucial effect on the relative energies of the dimethyl dodecahedranes. This supports the experimental results, in which all those except for 1,2-dimethyl derivative were synthesized. The LUMO of each of the derivatives was equivalently delocalized over the void within the cage, implying that dimethyl derivatives are able to encapsulate atoms at the center of the cage. The HOMO was limitedly delocalized on the cage. The characteristics of the HOMO of derivatives show three patterns, implying that each derivative might undergo one of three entirely different set of characteristic chemical reactions with electrophilic reagents.

Five regioisomers of dimethyl dodecahedrane derivatives: A hybrid DFT B3LYP study

254th National Meeting (2017)

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