Meaning of carbonium ion in English:

carbonium ion

Pronunciation /kɑːˈbəʊnɪəm ˌʌɪən/


  • An organic cation in which the positive charge is located on a carbon atom.

    ‘The key step in a unimolecular reaction is the formation of the carbon cation, or carbonium ion, by the departure of the leaving group.’
    • ‘This paper reviews the concept of carbonium ions, their formation, stability and reactions.’
    • ‘If a carbonium ion is involved in lysozyme catalysis then the TS structure will involve a planar, sp-hybridized C - 1.’
    • ‘Geometry optimisation using density function theory at the pBP / DN - level shows the carbonium ion to be trigonal bipyramidal.’
    • ‘The presence of a water molecule will provide the opportunity for the carbonium ion, and the left side of the ring, to become stable.’


Early 20th century carbonium from carbo-‘carbon’, on the pattern of ammonium.