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)Å3. 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.