Dipolar compound

{{Image frame|width=280|content=[R-\overset{\oplus}N{\equiv}\overset{\ominus}C{:} <-> R-\ddot{N}=C{:}]|caption=Example of a dipolar compound, represented by a resonance structure (isocyanide)}}

In organic chemistry, a dipolar compound or simply dipole is an electrically neutral molecule carrying a positive and a negative charge in at least one canonical description. In most dipolar compounds the charges are delocalized.{{GoldBookRef|title=dipolar compounds|file=D01753}}

Unlike salts, dipolar compounds have charges on separate atoms, not on positive and negative ions that make up the compound. Dipolar compounds exhibit a dipole moment.

Dipolar compounds can be represented by a resonance structure. Contributing structures containing charged atoms are denoted as zwitterions.

Braida et al.: [https://www.ncbi.nlm.nih.gov/pubmed/20481497 A clear correlation between the diradical character of 1,3-dipoles and their reactivity toward ethylene or acetylene.]; J. Am. Chem. Soc.; 2010 Jun 9;132(22):7631-7

Hartmann and Heuschmann: [http://onlinelibrary.wiley.com/doi/10.1002/anie.198912671/abstract Isolation of a Zwitterion in a Diels–Alder Reaction with Inverse Electron Demand]; Angewandte Chemie; september 1989; Volume 28, Issue 9, pages 1267–1268

{{cite journal|last1=MacHiguchi|first1=Takahisa|last2=Okamoto|first2=Junko|last3=Takachi|first3=Junpei|last4=Hasegawa|first4=Toshio|last5=Yamabe|first5=Shinichi|last6=Minato|first6=Tsutomu|title=Exclusive Formation of α-Methyleneoxetanes in Ketene−Alkene Cycloadditions. Evidence for Intervention of Both an α-Methyleneoxetane and the Subsequent 1,4-Zwitterion|journal=Journal of the American Chemical Society|volume=125|issue=47|pages=14446–8|year=2003|pmid=14624592|doi=10.1021/ja030191g|bibcode=2003JAChS.12514446M }}

Preferred IUPAC Names: [http://old.iupac.org/reports/provisional/abstract04/BB-prs310305/Chapter7.pdf "CHAPTER 7: RADICALS, IONS, AND RELATED SPECIES"], September 2004, pp. 56-70

Rolf Huisgen (IUPAC): [http://www.iupac.org/publications/pac/52/10/2283/pdf/ Cycloaddition mechanism and the solvent dependence of rate]; Pure Appl. Chem.; 1980, Vol.52, pp.2283—2302.

Some dipolar compounds can have an uncharged canonical form.