> See also: > - [[Chair Conformations]] # Chemical Bond Rotations Molecular Conformations Some molecules are constantly changing shape due to **free rotation** ## Newman Projections A **Newman projection** is a drawing of a molecule's conformation from the perspective of "looking down" a specific bond - The represented bond is drawn looking down the bond axis - The *front* atom is implied at the intersection of the groups attached to it (excluding the *back* atom) - The *back* atom is drawn as a circle with the groups attached to it, excluding the *front* atom - The bond between the *front* and *back* atom is implied (sometimes a dot at the center) ![[Newman Projection Example.png|300]] **Free rotation** can only occur in single ($\sigma$) bonds - Due to the layout of $\pi$ bond orbitals (within double and triple bonds), they are not capable of rotating without breaking. --- **Dihedral/torsional angles** are the angles between the two different planes of atoms bonded to the A *staggered* conformation will have $60\degree$ dihedral angles between the *closest* atoms An *eclipsed* conformation has $0\degree$ dihedral angles between the *closest* atoms - Often drawn slightly skewed for the sake of visibility