rac-2-Iodo-3,4-dihydronaphthalen-1(2H)-one

In the title compound, C10H9IO, the asymmetric unit contains two molecules, in which the iodo-bearing six-membered rings adopt envelope conformations [displacements of the flap atoms = 0.419 (3) and 0.431 (3) Å]. In both molecules, the I atoms are disordered over two set of sites in 0.54 (4):0.46 (4) and 0.71 (3):0.29 (3) ratios. In the crystal, the packing features a weak C—H⋯π interaction.

In the title compound, C 10 H 9 IO, the asymmetric unit contains two molecules, in which the iodo-bearing six-membered rings adopt envelope conformations [displacements of the flap atoms = 0.419 (3) and 0.431 (3) Å ]. In both molecules, the I atoms are disordered over two set of sites in 0.54 (4):0.46 (4) and 0.71 (3):0.29 (3) ratios. In the crystal, the packing features a weak C-HÁ Á Á interaction.

D-HÁ
Cg3 is the centroid of the C11-C16 ring.
The asymmetric unit of title compound consists of two individual molecules which are clearly racemate. In the molecule having (S)-configuration, the I-atom containing ring A (C1/C6/C7-C10) is twisted with maximum puckering amplitude Q T = 0.431 (3) Å, whereas in (R)-configuration the puckering parameter is Q T = 0.419 (3) Å. In two molecules the groups of benzene rings along with two adjacent C-atoms, C (C1-C6/C7/C10) and D (C11-C16/C17/C20) are planar with maximum r. m. s. deviations of 0.0114 and 0.0280 Å respectively, from the respective mean square planes. The dihedral angle between C/D is 66.83 (7) Å. In the first molecule the I-atom is disordered over two set of sites having occupancy ratio of 0.54 (4):0.46 (4). Similarly in the other molecule the I-atom is disordered over two set of sites having occupancy ratio of 0.71 (3):0.29 (3). The molecules are stabilized due to C-H···π interactions (Table 1).

Experimental
A solution of I 2 (7.75 g, 30.5 mmol) in CHCl 3 was added as drops to a solution of 1-tetralone (2.198 g, 15.2 mmol) in acetic acid (9.156 g, 0.1526 mol) and refluxed for 28 h. The H 2 O (30 ml) was added for partitioning. The reaction mixture was extracted with CHCl 3 (3 × 15 ml). The combined organic layer was concentrated in vacuo, the crude was dissolved in ethyl acetate, washed with 5% Na 2 S 2 O 3 (2 × 15 ml), dried over anhydrous Na 2 SO 4 , filtered, boiled with charcoal, concentrated under reduce pressure and allowed for crystallization, which afforded colourless prisms (89%) of (I).

Refinement
The other H-atoms were positioned geometrically (C-H = 0.93-0.98 Å) and refined as riding with U iso (H) = 1.2U eq (C). Fig. 1. View of (I) with the I atoms having greater occupancies. The displacement ellipsoids are drawn at the 30% probability level.