Difference Between Staggered and Eclipsed Conformation

Main Difference – Staggered vs Eclipsed Conformation

The term conformation describes different forms of projections of a molecule. In other words, it is the name given for different positions that a molecule can be bent into. The arrangement of atoms in a molecule has a great effect on the strain of the molecule. The stability of a molecule is high if it has a low strain conformation. Newman projections, which are commonly used in alkane stereochemistry, show the conformation of the molecule when looked through the C-C bond in the front-back direction. Staggered conformation and eclipsed conformation are two types of Newman projections that show the spatial arrangement of atoms. The main difference between staggered conformation and eclipsed conformation is that staggered conformation has a lower potential energy whereas eclipsed conformation has the maximum potential energy.

Key Areas Covered

1. What is Staggered Conformation
      – Definition, Structure, and Examples
2. What is Eclipsed Conformation
      – Definition, Structure, and Examples
3. What is the Difference Between Staggered and Eclipsed Conformation
      – Comparison of Key Differences

Key Terms: Alkanes, Dihedral Angle, Eclipsed Conformation, Ethane, Newman Projections, Potential Energy, Staggered Conformation, Strain

What is Staggered Conformation

Staggered conformation is the arrangement of atoms or groups of atoms in a molecule, resulting in a 60^o dihedral angle. This conformation gives the molecule a low strain because the atoms or groups of atoms are positioned in such a way that the repulsions between the bond electron pairs are minimized. There are even spaces between atoms in the staggered conformation so that the repulsion between atoms is minimized. Therefore, it is the most stable conformation. This indicates that the molecules in their staggered conformation have a low potential energy when compared to other possible conformations.

Figure 1: Staggered
Conformation of Ethane

The above image shows the staggered conformation of ethane. Staggered conformation is the most stable among other possible conformations for ethane. That is due to the minimized repulsion between bond electron pairs of the C-H bonds.

What is Eclipsed Conformation

Eclipsed conformation is the arrangement of atoms or groups of atoms in a molecule resulting, in a 0^o dihedral angle. Therefore, the stability of this conformation is very low. Since there are no spaces between the atoms or groups of atoms in the eclipsed conformation, there is a high repulsion between the bond electron pairs. Thus, eclipsed conformation is less stable. In this arrangement, the strain between atoms is very high. Since this conformation is unstable, it indicates that this molecule has a high potential energy.

Figure 2: Eclipsed Conformation of Ethane

The above image shows a sketch of the eclipsed conformation of ethane. However, it is not the actual structure. The actual structure shows only three atoms since other three atoms are covered to the front three atoms.

Difference Between Staggered and Eclipsed Conformation

Definition

Staggered Conformation: Staggered conformation is the arrangement of atoms or groups of atoms in a molecule resulting in a 60^o dihedral angle.

Eclipsed Conformation: Eclipsed conformation is the arrangement of atoms or groups of atoms in a molecule resulting in a 0^o dihedral angle.

Potential Energy

Staggered Conformation: Staggered conformation has a lower potential energy.

Eclipsed Conformation:  Eclipsed conformation has the maximum potential energy.

Strain

Staggered Conformation: Staggered conformation is a low strain structure.

Eclipsed Conformation: Eclipsed conformation is a high strain structure.

Stability

Staggered Conformation: The stability of staggered conformation is high.

Eclipsed Conformation: The stability of eclipsed conformation is low.

Conclusion

Staggered conformation and eclipse conformation are two major forms of Newman projection. These structures give the structure of a molecule when looked through the carbon backbone from front-back direction. The main difference between staggered conformation and eclipsed conformation is that staggered conformation has a lower potential energy whereas eclipsed conformation has the maximum potential energy.

References:

1. “Staggered conformation.” Wikipedia, Wikimedia Foundation, 13 Aug. 2017, Available here. Accessed 25 Aug. 2017.
2. “Conformations of alkanes.” Conformations of alkanes | UW-Madison Department of Chemistry, Available here. Accessed 25 Aug. 2017.

Image Courtesy:

1. “Staggered and eclipsed” By Dissolution – Own work (CC BY-SA 3.0) via Commons Wikimedia