Putting tert‐Butyl Cation in a Bottle

Usually viewed as intermediates that become long-lived at low temperatures in superacidic media, simple alkyl carbocations such as the tert-butyl cation can be isolated as stable salts at room temperature when partnered with inert carborane anions. The X-ray crystal structures of tert-butyl (depicted), tert-pentyl, and methylcyclopentyl cations have been determined with CHB11Me5X6− counterions (X=Br or Cl). C blue; H white; B yellow; X green.