ion pair return

Also contains definitions of: external ion-pair return, hidden return, internal return
https://doi.org/10.1351/goldbook.I03233
The recombination of a pair of ions R+ and Z formed from @[email protected] of RZ. If the ions are paired as a @[email protected] and recombine without prior separation into a @[email protected] this is called 'internal ion-pair return':
I03233-1.png
It is a special case of 'primary @[email protected]'. If the ions are paired as a @[email protected] and form the covalent chemical species via a @[email protected], this is called 'external ion-pair return':
I03233-2.png
It is a special case of 'secondary @[email protected]'. When the covalent molecule RZ is reformed without direct evidence of prior partial @[email protected] or without other direct evidence of prior formation of a @[email protected], (e.g. without partial @[email protected] if the group R is suitably @[email protected]) the internal ion-pair return is sometimes called a 'hidden return'. External (@[email protected]) ion-pair return is to be distinguished from 'external (@[email protected]) ion return', the (reversible) process whereby dissociated ions are converted into loose ion pairs:
I03233-3.png
Source:
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1127 [Terms] [Paper]