Infrared and Raman studies on the rotational isomerism in 2-chloro-, 2-bromo-, and 2-iodo-2-methylbutanes

Abstract

A suggested assignment of the vibrational frequencies of the trans and gauche isomers of the 2-halogeno-2-methylbutanes has been carried out. The frequencies of most of the vibrational modes were independent of the conformation of the molecule. The relative energies of the rotational isomers are determined mainly by intramolecular steric repulsive and electrostatic attractive non-bonded forces. In the liquid phase, however, the energies of the trans isomers also depend on intermolecular forces.