Revisiting the Conformational Isomerism of Dihaloethanes: A Hybrid Computational and Experimental Laboratory for the Undergraduate Curriculum.

Abstract

The conformational isomerism of disubstituted ethanes is a well-known concept that is part of every chemistry curriculum. Due to the species' simplicity, studying the (free) energy difference between the gauche and anti isomers has been the testing ground of experimental and computational techniques, such as Raman and IR spectroscopy, quantum chemistry, and atomistic simulations. While students normally receive formal training in spectroscopic techniques during their early undergraduate years, computational methods often receive less attention. In this work, we revisit the conformational isomerism of 1,2-dichloroethane and 1,2-dibromoethane and design a hybrid computational and experimental laboratory for our undergraduate chemistry curriculum with a focus on introducing computational techniques as a complementary research tool to experimentation. We show how commonly available Raman spectrometers and atomistic simulations performed on desktop computers can be combined to study the conformational isomerism of disubstituted ethanes while discussing the advantages and limitations of the different approaches.