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 methyl-cyclopentyl cations have been determined with CHB 11Me5X6- counterions (X= Br or Cl). C blue; H white; B yellow; X green.