Torsional strain occurs when atoms separated by three bonds are placed in an eclipsed conformation instead of the more stable staggered conformation.
12.
It had been accepted as early as the 1930s that the staggered conformations of ethane were more stable than the eclipsed conformation.
13.
The analysis of the curves determined that the staggered conformation had no connection to the amount of electrostatic repulsions within the molecule.
14.
The staggered conformation is more stable by 12.5 mol than the eclipsed conformation, which is the energy maximum for ethane.
15.
In contrast to ferrocene, wherein the cyclopentadienyl rings are in a staggered conformation, those of ruthenocene crystallise with an eclipsed conformation.
16.
These results demonstrate that Coulombic forces do not explain the favored staggered conformations, despite the fact that central bond stretching decreases electrostatic interactions.
17.
In the staggered conformation, one C-H sigma bonding orbital donates electron density to the antibonding orbital of the other C-H bond.
18.
The crystal structure of octaphenylrhodocene shows a staggered conformation ( similar to that of ferrocene, and in contrast to the eclipsed conformation of ruthenocene ).
19.
As far back as 1890 1891, chemists suggested that ethane molecules preferred the staggered conformation with the two ends of the molecule askew from each other.
20.
Wilson had proven that the energy barrier between any pair of eclipsed and staggered conformations is approximately 3 kcal / mol, and the generally accepted rationale for this was the unfavorable steric interactions between hydrogen atoms.
