zwitterionic compounds/zwitterions

Also contains definition of: dipolar ions
Synonym: inner salts
Neutral compounds having formal unit electrical charges of opposite sign. Some chemists restrict the term to compounds with the charges on non-adjacent atoms. Sometimes referred to as inner salts, dipolar ions (a misnomer). E.g. H3N+CH2C(=O)O ammonioacetate (glycine), (CH3)3N+–O trimethylamine oxide.
See: betaines, dipolar compounds, ylides
PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1176 (
PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1375 (