| Summary: | X-ray diffraction analysis and IR spectroscopy were used to study the products of the interaction of vinyl cations C<sub>3</sub>H<sub>5</sub><sup>+</sup> and C<sub>4</sub>H<sub>7</sub><sup>+</sup> (Cat<sup>+</sup>) (as salts of carborane anion CHB<sub>11</sub>Cl<sub>11</sub><sup>−</sup>) with basic molecules of water, alcohols, and acetone that can crystallize from solutions in dichloromethane and C<sub>6</sub>HF<sub>5</sub>. Interaction with water, as content increased, proceeded via three-stages. (1) adduct Cat<sup>+</sup>·OH<sub>2</sub> forms in which H<sub>2</sub>O binds (through the O atom) to the C=C<sup>+</sup> bond of the cation with the same strength as seen in the binding to Na in Na(H<sub>2</sub>O)<sub>6</sub><sup>+</sup>. (2) H<sup>+</sup> is transferred from cation Cat<sup>+</sup>·OH<sub>2</sub> to a water molecule forming H<sub>3</sub>O<sup>+</sup> and alcohol molecules (L) having the CH=CHOH entity. The O- atom of alcohols is attached to the H atom of the C=C<sup>+</sup>-H moiety of Cat<sup>+</sup> thereby forming a very strong asymmetric H–bond, (C=)C<sup>+</sup>-H⋅⋅⋅O. (3) Finally all vinyl cations are converted into alcohol molecule L and H<sub>3</sub>O<sup>+</sup> cations, yielding proton disolvates L-H<sup>+</sup>-L with a symmetric very strong H-bond. When an acetone molecule (Ac) interacts with Cat<sup>+</sup>, H<sup>+</sup> is transferred to Ac giving rise to a reactive carbene and proton disolvate Ac-H<sup>+</sup>-Ac. Thus, the alleged high reactivity of vinyl cations seems to be an exaggeration.
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