meso-1,11-Dimethylcyclotrideca-2,9-diyne-1,11-diol

The title compound, C₁₅H₂₂O₂, (5), has been prepared and its structure determined. At room temperature two conformations are observed, but at 193 K, the compound shows only the conformation which has 67% occupancy at room temperature. The appearance of two conformations and the low symmetry of compound (5) are in accordance with the general structural behaviour of 13-membered ring systems. meso-(5) crystallizes in the monoclinic space group I2/a. The lengths of the triple bonds are close to 1.175 Å at room temperature and 1.188 Å at 193 K. The bond angles at the triple bonds deviate by less than 7° from linear and are almost temperature independent.

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