Methyl 2-hydroxy-4-iodobenzoate

The title compound forms a sheet structure of dimers exhibiting intra- and intermolecular hydrogen bonds.

The structure of the title compound, C 8 H 7 IO 3 , at 90 K has monoclinic (P2 1 /c) symmetry.The extended structure is layered and displays intermolecular and intramolecular hydrogen bonding arising from the same OH group.
At 90 K the title compound displays monoclinic (P2 1 /c) symmetry with one molecule in the asymmetric unit (Fig. 1).Intermolecular hydrogen bonding interactions occur between the hydroxy groups of one molecule and the carbonyl oxygen atom of the methyl ester of an adjacent molecule to form a centrosymmetric dimeric pair (Table 1, Fig. 2) with H� � �O = 2.53 (4) A ˚.An O3-H3� � �O2 intramolecular hydrogen bond also exists with an H� � �O distance of 2.05 (4) A ˚.The C5� � �C8 [3.326 (3) A ˚] and O3� � �H1C (2.51A ˚) interactions provide the only short contacts between the stacks of offset (102) parallel sheets, which make up the crystal (Fig. 3).These sheets, in turn, contain the inversiongenerated hydrogen-bonded dimers (Fig. 2).The non-hydrogen atoms of the molecule are essentially coplanar with no displacement from the mean molecular plane greater than 0.132 A ˚(Fig. 4).

Figure 2
The dimer of title compound showing intra-and intermolecular hydrogen bonds depicted with blue dashed lines with corresponding O� � �H distances for each O-H� � �O interaction.

Figure 4
Packing diagram viewed along b-axis and parallel to (102).

Special details
Geometry.All esds (except the esd in the dihedral angle between two l.s.planes) are estimated using the full covariance matrix.The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry.An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s.planes.Refinement.The O-bound H atom was located in a difference map and its position was freely refined.The C-bound H atoms were geometrically placed (C-H = 0.95-0.98Å) and refined as riding atoms.

Figure 1 F
Figure 1The molecular structure of the title compound showing 50% displacement ellipsoids.The intramolecular hydrogen bond is indicated by a red dashed line.

Table 2
Experimental details.