text: In organic chemistry, a 1,3-dipolar compound or 1,3-dipole is a dipolar compound with delocalized electrons and a separation of charge over three atoms. They are reactants in 1,3-dipolar cycloadditions.
  The dipole has at least one resonance structure with positive and negative charges having a 1,3 relationship which can generally be denoted as , where a may be a carbon, oxygen or nitrogen, b may be nitrogen or oxygen, and c may be a carbon, oxygen or nitrogen.
  Known 1,3-dipoles are:
  * Azides ()
  * Ozone ()
  * Nitro compounds ()
  * Diazo compounds ()
  * Some oxides
  ** Azoxide compounds (RN(O)NR)
  ** Carbonyl oxides (Criegee zwitterions)
  ** Nitrile oxides ()
  ** Nitrous oxide ()
  ** Nitrones ()
  * Some imines:
  ** Azomethine imine
  ** Nitrilimines (, analogous to nitrile oxide)
  ** Carbonyl imines
  * Some ylides
  ** Azomethine ylide
  ** Nitrile ylide ()
  ** Carbonyl ylide
  ** Thiosulfines ()