Radical ion

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IUPAC RECOMMENDATIONS 2013

K. K. Murray, R. K. Boyd, M. N. Eberlin, G. J. Langley, L. Li and Y. Naito, Pure Appl. Chem., 2013, 85, 1515-1609, 10.1351/PAC-REC-06-04-06.

Radical ion
radical ion

odd-electron ion

Cation or anion containing unpaired electrons in its ground state. An unpaired electron is denoted by a superscript dot following the superscript symbol for charge, such as for the molecular ion of a molecule M, that is, M+•. Radical ions with more than one charge and/or more than one unpaired electron are denoted using parentheses, for example, as M(2+)(2•).

Note 1:Unless the positions of the unpaired electron and charge can be associated with specific atoms, superscript charge designation should be placed before the superscript dot designation.
Note 2: The order of the unpaired electron and charge are reversed from that recommended for organic and inorganic chemistry in which the dot representing the unpaired electron precedes the symbol for the charge. This convention is widely used in the mass spectrometry field and has been in place for many decades, and is retained here for that reason.
Note 3: It is not recommended that the charge designation be placed directly above the centrally placed dot because of the difficulty of extending it to ions bearing more than one charge and/or more than one unpaired electron.
Related Term(s):
Reference(s):

IUPAC. Analytical Division. Compendium of Analytical Nomenclature (the “Orange Book”). Definitive Rules, 1979. Compiled by J. Inczédy, T. Lengyel, A. M. Ure. Blackwell Scientific Publications, Oxford (1997). On-line corrected version: http://www.iupac.org /publications/analytical compendium (2000).

IUPAC. Compendium of Chemical Terminology, 2nd ed. (the “Gold Book”). Compiled by A. D. McNaught and A.Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins.

Definitions of Terms Relating to Mass Spectrometry (IUPAC Recommendations 2013); DOI: 10.1351/PAC-REC-06-04-06 © IUPAC 2013.


Index of Terms

 




Orange Book

ORANGE BOOK DEFINITION

IUPAC. Analytical Division. Compendium of Analytical Nomenclature (the “Orange Book”). Definitive Rules, 1979.

Radical ion

This is an ion containing an unpaired electron, which is thus both an ion and a radical. In mass spectroscopy an unpaired electron is denoted by a superscript dot alongside the superscript symbol for charge, thus C2H6+• or SF6 -•. An alternative form (IUPAC Compendium of Chemical Terminology, 1987) used in inorganic and organic chemistry literature uses the symbolism as in X+. For species with more than one charge and/or more than one unpaired electron the styles XM(2+)(2•) or X(2•)(2+) are recommended.

IUPAC Orange Book Chapter 12
Index of Orange Book Terms


Gold Book

GOLD BOOK DEFINITION

IUPAC. Compendium of Chemical Terminology, 2nd ed. (the “Gold Book”). Compiled by A. D. McNaught and A.Wilkinson. Blackwell Scientific Publications, Oxford (1997).

Radical ion

A radical that carries an electric charge. A positively charged radical is called a ' radical cation ' (e.g. the benzene radical cation C6H6 •+ ); a negatively charged radical is called a ' radical anion ' (e.g. the benzene radical anion C2H6 •- or the benzophenone radical anion Ph2C-O•- - ). Commonly, but not necessarily, the odd electron and the charge are associated with the same atom. Unless the positions of unpaired spin and charge can be associated with specific atoms, superscript dot and charge designations should be placed in the order •+ or •- suggested by the name 'radical ion'. (e.g. C3H6•+ ).

Notes:

In the previous edition of this Compendium, it was recommended to place the charge designation directly above the centrally placed dot. However, this format is now discouraged because of the difficulty of extending it to ions bearing more than one charge, and/or more than one unpaired electron. In mass spectroscopic usage the symbol for the charge precedes the dot representing the unpaired electron.

IUPAC Gold Book
Index of Gold Book Terms