Electrically neutral molecules carrying a positive and a negative charge in one of their major canonical descriptions. In most dipolar compounds the charges are delocalized; however the term is also applied to species where this is not the case. 1,2-Dipolar compounds have the opposite charges on adjacent atoms. The term 1,3-dipolar compounds is used for those in which a significant canonical resonance form can be represented by a separation of charge over three atoms (in connection with 1,3-dipolar cycloadditions). Subclasses of 1,3-dipolar compounds include:

1. Allyl type $\ce{X=Y^{+}-Z^{−}}$$\ce{<->}$$\ce{X^{−}-Y^{+}=Z}$$\ce{<->}$$\ce{X^{+}-Y-Z^{−}}$$\ce{<->}$$\ce{X^{−}=Y-Z^{+}}$ $(\ce{X, Z = C, N, or O; Y = N or O})$
   See: azo imides, azomethine imides, azomethine ylides, azoxy compounds, carbonyl imides, carbonyl oxides, carbonyl ylides, nitro compounds, nitrones
2. Propargyl type $\ce{X#N^{+}-Z^{−}}$$\ce{<->}$$\ce{X^{−}=N^{+}=Z}$$\ce{<->}$$\ce{X^{−}=N-Z^{+}}$$\ce{<->}$$\ce{X-N=Z}$ $(\ce{X = C or O, Z = C, N, or O})$
   See: azides, diazo compounds, nitrile imides, nitrile oxides, nitrile ylides, nitrilium betaines
3. Carbene type $\ce{X{:}-C=Z}$$\ce{<->}$$\ce{X^{+}=C-Z^{−}}$ $(\ce{X = C or N; Z = C, N, or O})$
   See: acyl carbenes, betaines, imidoyl carbenes, vinyl carbenes