Also it was proposed that thiyl radical-promoted polycyclization to form dodecahedrane would be exergonic .
A dodecahedrane derivative, namely, the [D.sub.3d] symmetric 1,16-dimethyl derivative, has been synthesized experimentally [5-8].
The structures of dodecahedrane and its derivatives were studied at the level of molecular mechanics calculations [16, 17], INDO calculations , and hybrid density functional B3LYP calculations .
Our result suggests that both the strength of the cage distortion and the van der Waals force between the pair of methyl groups of derivatives are important factors that affect the position of exohedral dimethyl substitution on the dodecahedrane cage.
Here our calculations concerning the dimethyl dodecahedrane derivatives could explain the fact why three dimethyl dodecahedrane derivatives were reported in X-ray and NMR experiments [7, 15], but the 1,2-dimethyl dodecahedrane derivative has not been synthesized yet.
In the experimental results, dodecahedrane, methyl, and dimethyl derivatives are synthesized , but cis-1 and equatorial isomers are not synthesized yet.
Therefore, our calculations in the point of thermodynamic view could support the experimental results, wherein three dimethyl dodecahedrane derivatives except the 1,2-dimethyl dodecahedrane derivative were preparative-synthetic and suggest that 1,7-dimethyl derivative (equatorial, [C.sub.2]) would be synthesized in the near future.
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Taylor, "Total synthesis of a monosubstituted dodecahedrane. The methyl derivative," Journal of the American Chemical Society, vol.