AB-INITIO SCF INVESTIGATION OF THE INTRAMOLECULAR HYDROGEN-BONDING IN EPSILON-AMINOHEXANOIC ACID

Ab initio RHF results (geometry data and potential barriers) are reported for the 14 symmetry unique local minima in the potential energy surface of epsilon-aminohexanoic acid, which contain an intramolecular N...H-O hydrogen bond. Comparison of characteristic data with those of the homologs with fewer carbon atoms shows that delta-aminopentanoic acid forms the most stable hydrogen bonds. In contrast to these homologs, the -COOH group is not limited to anti-periplanar orientation in the H-bonded conformers of epsilon-aminohexanoic acid: In four such conformers, it occurs in ayn-clinal orientation. (C) 1994 John Wiley & Sons, Inc.