The Dependence of 1J(C, H) and 3J(C, H) on a Nitrogen Lone-pair and Carbonyl Group. Application to Diazepam

  • Ruth Pachter
  • Philippus L Wessels
Keywords: (C, H) coupling constants, Nitrogen lone-pair, Carbonyl group, INDO-FPT calculations, Diazepam

Abstract

The relatively large difference in the directly bonded (C, H) coupling constants of the C(3) methylene group in diazepam can be attributed to the spatial relationship of the C(3)-H bonds and the C(2)=O group and N(4)-lone pair. INDO-FTP calculated 1J(C-3, H) values reveal a linear relationship with the C(2)-C(3)-N(4)-C(5) dihedral angle, a non-linear relationship with the C-H bond length and small negative change depending on the N(1)-C(2)-C(3)-N(4) dihedral angle. The INDO-FTP calculated 3J(C-5, H) values depend on the corresponding dihedral angle and the spatial relationships of the C=N double bond and the aryl group.

Key Words: (C, H) coupling constants, Nitrogen lone-pair, Carbonyl group, INDO-FPT calculations, Diazepam

South African Journal of Chemistry Vol.57 2004: 37-39
Section
Articles

eISSN: 0379-4350