[chemical substances]
   reactive intermediates
     Class cations [X+]
       82.1.1.1 Class carbocations
       82.1.1.1 Class onium compounds
       82.1.1.2 Class arenium ions
       82.1.2 Class amidium ions
       82.2.3.4 Class sulfenylium ions [RS+ (R≠H)]