Molecular Rods Combining <i>o</i>‑Carborane
and Bicyclo[1.1.1]pentane Cages: An Insertion of the Triple Bond Located Next to a Highly Strained
Cage
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Abstract
Octacarbonyl
dicobalt and bis(dimethyl sulfide)decaborane B<sub>10</sub>H<sub>12</sub>(Me<sub>2</sub>S)<sub>2</sub> were successfully
added to 1,3-diethynylbicyclo[1.1.1]pentane in good yields. This is
an interesting example of a cycloaddition reaction achieved next to
the bicyclopentane cage that tends to rearrange in many other cases.
It proves that both reagents attack the triple bond in a more or less
concerted manner that prevents the rearrangement. Products of the
latter reaction are of a particular interest because the bicyclopentane
and <i>o</i>-carborane cages are immediately linked in their
rodlike structures. The new kind of molecular rotors was thus constructed. <sup>1</sup>H and <sup>13</sup>C nuclear magnetic resonance spectra in
solution reveal an averaged rotational symmetry of the molecules with
a well-defined geometry that has been confirmed by X-ray structural
analysis in several examples