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Synthesis and properties of a bis(2-buteno)-bridged bis(adamantane) : x-ray and molecular dynamic studies of the trans, trans isomer

The sinthesis of the trans,trans isomer of the bis(2-buteno)-bridged bis(adamantane) 3 has been developed, and its structure was established by spectral and X-ray structure analysis. Since the result of dynamic NMR studies indicate that 3 is conformationally mobile and the transition-state free energy required to interconvert two equivalent conformers was estimated to be ca. 60 kJ/mol, the lowest energy conformer was subjected to a molecular dynamic simulation at 323 K in the gas phase. Three conformations 3a, 3b and 3c were found. The conformations 3a and 3c have anti-oriented adamantane units, while in 3b the adamantane molecules occupy the syn conformation. By analysing the conformational processes in macrocyclic diene 3 it was found that the calculated conformation 3a with molecular symetry of C2h is very close to that found in solution at -50oC, but differs from that which was observed in the solid state by X-ray-crystallographic analysis.

bis(adamantane); bis(2-buteno)-bridged / synthesis / molecular dynamic studies

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