A theoretical study about factors affecting conformational stabiltiy order of glyoxime

摘要

In this study, stable conformers and the effects determining conformational stability of the glyoxime (GO) molecule are inspected. Semiemprical PM3 method is used for conformer distribution. Geometry optimizations are performed by MP2/6-311++G(d,p) level of theory. We obtained twenty stable conformers for the title compound; however conformer 1 is (approximately 17 kcal/mol) more stable than conformer 20. Calculated geometry parameters for the most stable conformer are consistent with experimental results. Long range electrostatic, conjugation, and hydrogen bonding effects are found responsible for stability order of GO. Four conformers which can be determined experimentally are isolated theoretically. Thermodynamic and geometrical parameters of these isomers are given first time in this study. Calculated relative energies of these conformers are very close to each other. For this reason, isolation of these conformers is very difficult for experimentalists. The chemical reactivities of GO conformers were investigated by HOMO-LUMO energy gaps.