The First Crystal Structure Analysis of Cyclododeca-2,8-diyne-1,10-diols

Cyclododeca-2,8-diyne-1,10-diol, (6), C₁₂H₁₆O₂, and 1,10-dimethylcyclododeca-2,8-diyne-1,10-diol, (11), C₁₄H₂₀O₂, have been prepared and their structures determined. Both crystallize in centrosymmetric space groups and the molecules have approximate C₂ symmetry. For compound (6), the lengths of the triple bonds are 1.184 (3) (C2[triple bond]C3) and 1.189 (3) Å (C8[triple bond]C9). The bond angles at the triple bonds (C1—C2[triple bond]C3 and C8[triple bond]C9—C10) deviate by less than 6° from 180°. For compound (11), the bond lengths of the triple bonds are 1.190 (3) (C2[triple bond]C3) and 1.188 (3) Å (C8[triple bond]C9), and the bond angles at the triple bonds are close to 175.5°. In both compounds, the two 3-hexyne chains maintain a `crossed' arrangement whereas the two alkylene chains are arranged in a manner similar to that described for unsubstituted cyclododecane.

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