CONFORMATIONAL ANALYSIS OF 2-FORMYL-1-METHYLPYRIDINIUM OXIME CATION BY EXTENDED HUCKEL MOLECULAR-ORBITAL CALCULATIONS.
Technical rept., Feb 65-Aug 66,
EDGEWOOD ARSENAL MD
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A theoretical, quantum-mechanical study of 2-pyridine aldoxime methiodide 2-PAMI was undertaken to delineate the pharmacologically active stereochemical state of the cation of the oxime. Twelve conformers of 2-PAMI were geometrically defined and were subjected to extended Huckel molecular-orbital quantum-mechanical calculation. A newly defined parameter, molecular total overlap population MTOP, was described and was shown to reflect stability and, in this study, to predict expected geometry. By analyzing total energy and MTOP, the least-stable isomeric pairs were N1T- and N3T- the most-stable planar isomeric pair was N3S, with N1S a close second the most stable of all conformers was the aldoxime out-of-plane OOP quartet. For any rotational state, the syn- oxime configuration was more stable than its respective anti- analog for any non-sterically hindered aldoxime-ring rotational and oxime configurational state, the proton anti- configurational state was more stable than its proton syn- analog. Although the exact expected geometry was not predictable from the three aldoxime-ring bond lengths chosen by using total energy alone, the MTOPs clearly indicated that maximal stability should occur between 1.40A and 1.55A for planar conformers and very close to 1.55A for OOP conformers. Author
- Organic Chemistry
- Chemical, Biological and Radiological Warfare