HYDROGEN-BONDING IN 3-AZETIDINOL .2. ON THE PRESENCE OF INTERMOLECULAR AND INTRAMOLECULAR INTERACTIONS IN SOLUTION AND IN THE GAS-PHASE

Investigations of the hydrogen bonding of 3-azetidinol in the solid state by X-ray spectroscopy have been extended to solutions in CCl4 and water. Ab initio calculations ranging from the STO-3G to the 6-31G** level indicate that in addition to the non-associated form (A) a conformer with intramolecular hydrogen-bonding OH ··N (B) might occur in the approximate ratio 2:1. IR and 1H NMR spectroscopic studies on CCl4 solutions give evidence in support of this prediction. The IR spectra at low temperatures (-5°C) disclose the presence of an intermolecular hydrogen- bonded chain-stacking form (C) which has a strong affinity to water. Raman spectra in the R (ν) representation of an aqueous solution of 3-azetidinol in the range -400 to 400 cm-1 support the presence of C. A structure for is proposed based upon the X-ray results, involving stacking of the azetidinol rings and strong intermolecular hydrogen bonding necessitating the incorporation of water molecules. The proposal is supported by the ab initio results. © 1990.