5-Amino-1-naphthol

In the title compound, C10H9NO, the amino and the hydroxy groups act both as a single donor and a single acceptor in hydrogen bonding. In the crystal, molecules are connected via chains of intermolecular ⋯N—H⋯O—H⋯ interactions, forming a two-dimensional polymeric structure resembling the hydrogen-bonded molecular assembly found in the crystal structure of naphthalene-1,5-diol. Within this layer, molecules related by a translation along the a axis are arranged into slipped stacks via π–π stacking interactions [interplanar distance = 3.450 (4) Å]. The amino N atom shows sp 3 hybridization and the two attached H atoms are located on the same side of the aromatic ring.

In the title compound, C 10 H 9 NO, the amino and the hydroxy groups act both as a single donor and a single acceptor in hydrogen bonding. In the crystal, molecules are connected via chains of intermolecular Á Á ÁN-HÁ Á ÁO-HÁ Á Á interactions, forming a two-dimensional polymeric structure resembling the hydrogen-bonded molecular assembly found in the crystal structure of naphthalene-1,5-diol. Within this layer, molecules related by a translation along the a axis are arranged into slipped stacks viastacking interactions [interplanar distance = 3.450 (4) Å ]. The amino N atom shows sp 3 hybridization and the two attached H atoms are located on the same side of the aromatic ring.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: SU2154).

5-Amino-1-naphthol
A. Czapik, A. Nitka and M. Gdaniec Comment Amino-hydroxy group recognition has been at the focus of crystal engineering since Ermer &Eling (1994) andHanessian et al. (1994) noticed the complementarity of hydroxy and amino groups as regards hydrogen-bond donors and acceptors.
Shortly after it was demonstrated with simple 1,2-and 1,3-aminophenols that molecular features, such as functional groups, do not necessarily result in a single manner of the molecular arrangement, and that strong N-H···O and O-H···N hydrogen bonding is frequently unable to exclude other factors from controlling the crystal packing (Allen et al., 1997;Dey et al. 2005). Here we report on the crystal structure of a simple aminonaphthol which, as regards the substitution pattern, can be considered as an analogue of 1,4-aminophenol.
The molecular structure of the title compound is shown in Fig. 1, and the geometrical parameters are available in the archived CIF. Whereas 1,4-aminophenol forms a tetrahedral network, via N-H···O and O-H···N hydrogen bonds (Ermer & Eling, 1994), in the title compound the molecules are connected via chains of ···N-H···O-H··· interactions to form a two-dimensional polymeric structure (Fig. 2, Table 1). The two-dimensional assembly of the molecules joined by hydrogen bonding resembles that formed by 1,5-dihydroxynaphthalene (Belskii et al., 1990). One amino H-atom is not involved in hydrogen bonding and does not take part in any other specific interactions.

Experimental
Single crystals of the commercially available 5-amino-1-naphthol (Aldrich) were obtained from chloroform solution by slow evaporation.

Refinement
In the absence of significant anomalous scattering effects, Friedel pairs were averaged. All H-atoms were located in electron-density difference maps. The H-atoms of the OH and NH groups were freely refined: O-H = 0.94 (3)     Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.