2,3-Dihydro-1H-cyclopenta[b]naphthalen-1-ol

In the title compound, C13H12O, the cyclopentene ring fused with the naphthalene group adopts an envelope conformation. The cyclopentene torsion angle, with the fusion bond at the centre, has a magnitude of 1.16 (16)°. In the crystal, neighbouring molecules are connected through O—H⋯O hydrogen bonds into an R 4 4(8) ring motif. The crystal packing also features weak π–π stacking interactions [centroid–centroid distance = 3.8981 (8) Å] and C—H⋯π interactions.

In the title compound, C 13 H 12 O, the cyclopentene ring fused with the naphthalene group adopts an envelope conformation. The cyclopentene torsion angle, with the fusion bond at the centre, has a magnitude of 1. 16 (16) . In the crystal, neighbouring molecules are connected through O-HÁ Á ÁO hydrogen bonds into an R 4 4 (8) ring motif. The crystal packing also features weakstacking interactions [centroidcentroid distance = 3.8981 (8) Å ] and C-HÁ Á Á interactions.
Data collection: CrysAlis PRO (Agilent, 2011); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999) and PLATON (Spek, 2009 (Carpino & Lin, 1990). Two signal groups, aliphatic and aromatic were observed in 1 H-NMR spectra. The H2 and H3 protons exhibited a AA′BB′ splitting pattern. H1 appeared at lower magnetic field than the 2,3 H atoms. This is due to the electronegativity of oxygen atom attached to C-1. The signal observed at δ 5.39 as a broad singlet could be attributed to OH group. Moreover a thirteen line 13 C-NMR spectrum supports the proposed structure.
The exact configuration of the molecule was established by X-ray diffraction.

Refinement
The H atom of the hydroxyl group was located in a difference Fourier map and refined freely. Carbon-bound H-atoms were placed in calculated positions and refined with constrained C-H bond lengths of 0.93 Å for aromatic, 0.97 Å for methylene and 0.98 Å for methine H atoms, and U iso (H) = 1.2 U eq (C) allowing them to ride on the parent C atom. The (6 6 0), (-6 12 0) and (-2 6 0) reflections were omitted owing to bad disagreement.

Figure 1
The title molecule with the atom numbering scheme. Displacement ellipsoids for non-H atoms are drawn at the 30% probability level.  The packing and hydrogen bonding of the title compound, viewing down the c axis. H atoms not involved in hydrogen bonding have been omitted. Special details Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses 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 observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs 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.