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 (C 7 H 7 NO 2 ) and 2-methoxybenzamide (C 8 H 9 NO 2) 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.