Back مكسوف Arabic Conformation éclipsée French 重なり形配座 Japanese Geëclipseerde conformatie Dutch Eklipsna konformacija Serbo-Croatian Zaclonená konformácia Slovak Eklipsna konformacija Serbian Eclipsed Swedish
(image right in Newman projection)
In chemistry an eclipsed conformation is a conformation in which two substituents X and Y on adjacent atoms A, B are in closest proximity, implying that the torsion angle X–A–B–Y is 0°.[1] Such a conformation can exist in any open chain, single chemical bond connecting two sp3-hybridised atoms, and it is normally a conformational energy maximum. This maximum is often explained by steric hindrance, but its origins sometimes actually lie in hyperconjugation (as when the eclipsing interaction is of two hydrogen atoms).
In the example of ethane, two methyl groups are connected with a carbon-carbon sigma bond, just as one might connect two Lego pieces through a single "stud" and "tube". With this image in mind, if the methyl groups are rotated around the bond, they will remain connected; however, the shape will change. This leads to multiple possible three-dimensional arrangements, known as conformations, conformational isomers (conformers), or sometimes rotational isomers (rotamers).[2]
- ^ Eliel, Ernest L.; Wilen, Samuel H. (1994). Stereochemistry of Organic Compounds. Wiley. p. 1197. ISBN 978-0-471-01670-0.
- ^ Ashenhurst, James (February 28, 2020). "Staggered vs Eclipsed Conformations of Ethane". Mastering Organic Chemistry. Retrieved November 15, 2022.