An IR, NMR, dipole moment and X-ray study on intramolecular O–H ⋯ N hydrogen bonding in 8-hydroxy-N,N-dimethyl-1-naphthylamine

Abstract

The X-ray diffraction structure at 85 K and physico-chemical properties of 8-hydroxy-N,N-dimethyl-1-naphthylamine have been studied. Five crystallographically independent molecules, of which two are disordered, are contained in the centrosymmetric triclinic unit cell of dimensions: a= 10.307(9), b= 13.459(9), c= 19.183(9)Å, α= 93.98(6), β= 102.91(6), γ= 97.05(9)°, V= 2561(3)ų. For the non-disordered molecules the mean length of the intramolecular O–H ⋯ N hydrogen bond is 2.569(5)Å and the H atom position is described by the 0.90(3) and 1.72(3)Å mean distance for O–H and H ⋯ N, respectively. Two of the crystallographically independent molecules are joined by a weak, bifurcated O–H ⋯ O hydrogen bond with O ⋯ O distance of 2.878(2)Å. The studies of ¹H NMR, IR spectra and dipole moments indicate the presence of fairly strong O–H ⋯ N hydrogen bonding. The dipole moments and ¹H NMR data in cyclohexane, CCl₄, benzene and dioxane show weak association, particularly in cyclohexane and CCl₄. The results demonstrate that association leads to the formation of non-polar dimers. In dioxane a compeexation with the solvent molecules takes place without the breaking of intramolecular hydrogen bonds.