problem 9.75

[Sara Varadharajulu]

what is the difference between cis and trans isomers?

[Sally Nason - 1K]

For cis compounds there are 12 different orientations but for trans compounds there are only 3 different orientations. Therefore, the cis form will have higher residual energy (use Boltzmann entropy calculations).

[Cassandra Mullen 1E]

Just to add on, the 12 orientations/3 orientations come from the octahedral shape (6 directions for the ligands), which is the same for both the cis and trans isomers. In the trans isomer, the ligands are across from each other, and in the cis isomer, the ligands are next to each other. Rotating the cis isomer results in more positions, so the cis isomer has higher residual entropy.