Coming Soon - Stereogenic unit edit
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A stereogenic unit (also known as a stereogenic element, stereoelement or stereogen), is group of connected atoms within a molecule that may be a source of stereoisomerism. A stereogenic unit is a more encompassing concept than the stereocenter.
The presence of a stereogenic unit enables a molecule to exhibit enantiomerism or diastereomerism, however the presence of a stereogenic unit does not necessarily imply chirality.
According to the IUPAC definition,[1] three basic types of stereogenic units are recognized for molecular entities involving atoms having not more than four substituents:
- A central atom surrounded by a group of distinguishable substituents (or ligands), such that the interchange of any two of the substituents leads to a stereoisomer.
- A chain of four non-coplanar atoms (or rigid groups) in a stable conformation, with restricted rotation such that (an imaginary or real) rotation about the central bond leads to a stereoisomer.
- A grouping of atoms consisting of a double bond and substituents which can exhibit cis-trans isomerism.
See also edit
References edit
- ^ 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. ISBN 0-9678550-9-8. http://goldbook.iupac.org/S05980.html.