Molecular form in which substituents on two adjacent atoms are closest together
"Eclipsed" redirects here. For other uses, see Eclipse (disambiguation).
Main article: Alkane stereochemistry
Eclipsed conformation (image right in Newman projection)Staggered conformation
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 order to gain a deeper understanding of eclipsed conformations in organic chemistry, it is first important to understand how organic molecules are arranged around bonds, as well as how they move and rotate.
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.
and 28 Related for: Eclipsed conformation information
In chemistry an eclipsedconformation is a conformation in which two substituents X and Y on adjacent atoms A, B are in closest proximity, implying that...
eclipsedconformations with dihedral angles of 0°, 120°, and 240° are transition states between conformers. Note that the two eclipsedconformations have...
six conformations, three will be in a staggered conformation, while the other three will be in an eclipsedconformation. These six conformations can be...
the opposite of an eclipsedconformation, in which those substituents are as close to each other as possible. Such a conformation exists in any open chain...
two 1,3 diaxial interactions). This eclipsed position increases the steric strain on the cyclohexane conformation and the confirmation will shift towards...
is unrealistic, as a saccharide would never adopt this multiply eclipsedconformation. Nonetheless, the Fischer projection is a simple way of depicting...
two pi bonds and one delta bond. The [Re2Cl8]2− ion adopts an eclipsedconformation as shown at left. The delta bonding orbital is then formed by overlap...
single bond. Two limiting conformations are important: eclipsedconformation and staggered conformation. The staggered conformation is 12.6 kJ/mol (3.0 kcal/mol)...
ring to adopt a staggered conformation. For cyclohexene, however, the alkene is planar, equivalent to an eclipsedconformation at that bond. Diels-Alder...
transition state has staggered conformation with lower energy than a synperiplanar transition state which is in eclipsedconformation with higher energy. The...
as they showcase the structure of a molecule in the staggered or eclipsedconformation states. The wedge and dash notation will help to showcase the stereochemistry...
cyclopentadienyl rings are in a staggered conformation, those of ruthenocene crystallise with an eclipsedconformation. This difference is due to the larger...
conformation, thus causing all four cubic-diagonal directions to be equivalent; whereas in lonsdaleite the bonds between layers are in the eclipsed conformation...
staggered conformations of ethane were more stable than the eclipsedconformation. Wilson had proven that the energy barrier between any pair of eclipsed and...
Felkin argued that the Cram model suffered a major drawback: an eclipsedconformation in the transition state between the carbonyl substituent (the hydrogen...
conformational flexibility. Thus, the substituents of ring atoms exist in an eclipsedconformation in cyclopropanes and between gauche and eclipsed in...
octaphenylrhodocene shows a staggered conformation (similar to that of ferrocene, and in contrast to the eclipsedconformation of ruthenocene). The rhodium–centroid...
dithionate ion is like ethane, but two SO3 groups adopt an almost eclipsedconformation. The S—S bond length is about 2.15 Å; the S—O bonds are rather short...
"inside" addition produces a results in a staggered conformation, rather than the eclipsedconformation that results from the "outside" addition. The transition...
ring strain, the molecule also has torsional strain due to the eclipsedconformation of its hydrogen atoms. The C-H bonds in cyclopropane are stronger...
is likely facilitated by the eclipsedconformation of the phosphoryl groups when ATP is bound to PEPCK. Since the eclipsed formation is one that is high...
two cyclopentadienyl rings in an eclipsedconformation like ruthenocene and osmocene and not in a staggered conformation like ferrocene. Hassocene, which...
molecule has significant levels of torsional strain as a result of the eclipsedconformation along each edge of the structure. The molecule has perfect icosahedral...
would be eclipsed bonds. Therefore, to reduce torsional strain, cyclohexane adopts a three-dimensional structure known as the chair conformation, which...
reveal both eclipsed or staggered rotamers. For non-substituted metallocenes the energy difference between the staggered and eclipsedconformations is only...
ring planes is approximately 6.40 Å. The C5Me5 rings are in an eclipsedconformation with the methyl substituents bent slightly outward (away from the...
In the study of conformational isomerism, the gauche effect is an atypical situation where a gauche conformation (groups separated by a torsion angle of...
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