Hydrogen Bonding in the Gas-Phase: The Molecular Structures of 2-Hydroxybenzamide (C₇H₇NO₂) and 2-Methoxybenzamide (C₈H₉NO₂), Obtained by Gas-Phase Electron Diffraction and Theoretical Calculations

Abstract

The structures of 2-hydroxybenzamide (C7H7NO2) and 2-methoxybenzamide (C8H9NO2) have been determined in the gas-phase by electron diffraction using results from quantum chemical calculations to inform restraints used on the structural parameters. Theoretical methods (HF and MP2/6-311+G(d,p)) predict four stable conformers for both 2-hydroxybenzamide and 2-methoxybenzamide. For both compounds, evidence for intramolecular hydrogen bonding is presented. In 2-hydroxybenzamide, the observed hydrogen bonded fragment is between the hydroxyl and carbonyl groups, while in 2-methoxybenzamide, the hydrogen bonded fragment is between one of the hydrogen atoms of the amide group and the methoxy oxygen atom.