Accession Number : AD0649312

Title :   CONFORMATIONAL ANALYSIS OF 2-FORMYL-1-METHYLPYRIDINIUM OXIME CATION BY EXTENDED HUCKEL MOLECULAR-ORBITAL CALCULATIONS.

Descriptive Note : Technical rept., Feb 65-Aug 66,

Corporate Author : EDGEWOOD ARSENAL MD

Personal Author(s) : Giordano,Wally P. ; Hamann,Jon ; Harkins,Jerry ; Kaufman,Joyce

Report Date : APR 1967

Pagination or Media Count : 27

Abstract : 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 MTOP's 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)

Descriptors :   (*DRUGS, *STEREOCHEMISTRY), (*PYRIDINES, STEREOCHEMISTRY), (*MOLECULAR ORBITALS, STEREOCHEMISTRY), OXIMES, IODIDES, MOLECULAR ISOMERISM, CHEMICAL BONDS, STABILITY, CRYSTALLOGRAPHY, MOLECULAR STRUCTURE, QUANTUM THEORY

Subject Categories : Pharmacology
      Organic Chemistry
      Chemical, Biological and Radiological Warfare

Distribution Statement : APPROVED FOR PUBLIC RELEASE