Influence of exchange interactions on molecular conformation: stability of the gauche conformer of n-propylhalides

✍ Scribed by E. Lombardi; G. Tarantini

• Publisher: Elsevier Science
• Year: 1978
• Tongue: English
• Weight: 659 KB
• Volume: 59
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(78)89097-6

✦ Synopsis

The infhrence of exchange interactions on molecular conformations is ihustrated by considering their role in stabilizing the gauche conformation of the npropylhalides. The conformational energy is c&Mated as a sum of exchange Interactions for ciusters of non-bonded atoms. The exchange component is evaluated in fust order of perturbation theory, in the approximation of one "effective" electron per non-bonded atom, plus a three-atom indirect exchange ("superexchange*') contribution invol-vg the core electrons of a heavy (halogen) atom in the molecule. It is shown that the greater stability of the gauche form may be due to the three-atom indirect exchange interactions associated to the triplet formed by the halogen atom, the carbon atom belonging to both axes of internal rotation and that hydrogen Rhich is facing the halogen atom. We fmd satisfactory agreement between calculated and experimental results_