Origin of the gauche preference of n-propyl halides and related molecules investigated by ab initio MO calculations: Importance of the CH/n hydrogen bond

Ab initio MO calculations were carried out to investigate the conformational preference of n-propyl halides, isobutyl halides, sec-butyl halides, and n-butyl halides. It has been found in most cases that the conformer in which a methyl group is close to the halogen atom is favored.