Structural Effects in Amides. Crystal and Molecular Structures of Phosphoric and Carboxylic Anilides

Article abstract of DOI:10.1021/jo00133a016

Crystal and molecular structures of three N-aryl carboxylic amides (RCONHAr) and three dimethyl N-arylphosphoramidates (MeO)2P(O)NHAr were determined and are discussed together with those of related systems described in the literature.Carboxylic amides exist in the trans configuration of the CO and NH groups, and both the N-aryl and C-aryl (for R = Ar) rings are considerably twisted with respect to the amide plane.Phosphoramidates prefer the cis orientation of the PO and NH groups, with the N-aryl group bisecting the MeO-P-OMe angle.Substituents in the N-aryl group have a weak effect on structural parameters of both amide functions.For the phosphoramidates a linear free-energy relationship between the intramolecular P=O...H-N hydrogen bonding and the acidity of the ArNH3⁺ ions has been obtained.