Carborane Formation in Alkyne-Borane Gas Phase Systems. V. Conversion of Two-Carbon to Four-Carbon Carboranes via Alkyne Insertion. NMR Studies of Tetracarba-nido-hexaboranes.
VIRGINIA UNIV CHARLOTTESVILLE DEPT OF CHEMISTRY
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The reaction of the square pyramidal carborane 1,2-C2B3H7 with acetylene yields one volatile product, 2,3,4,5-C4B2H6, a carborane of pentagonal pyramidal geometry. The process occurs as a straightforward insertion into the carborane cage, as shown by the use of deuterium- or carbon-13-labeled acetylene. The reaction of 1,2-C2B3H7 with methylacetylene produces 3-CH3C4B2H5 and a lesser quantity of 2-CH3C4B2H5, while the reaction with dimethylacetylene generates predominantly 2,3-CH32C4B2H4 with a smaller amount of 3,4-CH32C4B2H4. The results indicate that alkyne insertion into C2B3H7 occurs primarily at C-B bonds without C-C cleavage, but that insertion into the carborane C-C bond also occurs to a significant extent. The proton and boron-11 NMR spectra of the C4B2H6 derivatives are correlated with structural features and the spectra of the parent compound are interpreted. Author
- Inorganic Chemistry