Draw the Newman projections of the 1R,2S and the 1R,2R (and 1S,2S)-stilbene

[Anita]

dibromides? Although free rotation is possible around the single bond connecting the chiral carbon atoms of the
stilbene dibromides, evidence from dipole-moment measurements indicates that the molecules tend to
exist predominately in the specific shape or conformation in which the two phenyl groups repel each
other and occupy positions as far apart as possible. Draw the Newman projections of the 1R,2S and
the 1R,2R (and 1S,2S)-stilbene dibromides. Which structure (conformer) is more stable? Why?