The chair conformation is the favored configuration, because in this conformation, the steric strain, eclipsing strain, and angle strain that are otherwise possible are minimized.
12.
Alkyne insertion occurs so that the large substituent on the alkyne avoids steric strain from the short developing carbon-carbon bond by interacting with the longer carbon-palladium bond.
13.
Van der Waals strain, or steric strain, occurs when atoms are forced to get closer than their tert-butyl groups take up much more space than methyl groups and often experience greater steric interactions.
14.
The reason is that this molecule is very unstable because its amide group has the amine lone pair and the carbonyl group not properly aligned, as may be expected for an amide, as a result of steric strain.
15.
An example of interactions within a molecule that would lead to steric strain, leading to a shift in equilibrium from boat to chair, is the interaction between the two methyl groups in " cis "-1, 4-dimethylcyclohexane.
16.
Along this same vein, allenyl vinyl ketones of the type studied extensively by Marcus Tius of the University of Hawaii show dramatic rate acceleration due to the removal of ?-hydrogens, obviating a large amount of steric strain in the s-cis conformer.
17.
The greater variation in the substituted ligand is attributed to the distortions necessary to relieve the steric strain imposed by neighbouring " tert "-butyl substituents; despite these variations, the data demonstrate that the substituted cyclopentadienyl is also ? 5-coordinated.
