Potassium 2-iodobenzenesulfonate monohydrate

In the crystal structure of the title compound, K+·C6H4IO3S−·H2O, the potasium cation is 2.693 (3)–2.933 (3) Å from the sulfonate and water O atoms (including symmetry-related atoms) and forms a two-dimensional sheet-like structure in the bc plane, with the iodobenzene rings protruding above and below. The water molecule of crystallization is hydrogen-bonded to sulfonate O atoms within this two-dimensional arrangement. Symmetry-related iodobenzene rings are arranged perpendicular to one another with the I atom ca 4.1 Å from the centroid of the neighbouring benzene ring. In the crystal structure, these two-dimensional sheet-like supramolecular structures are arranged parallel to one another, stacked along the a-axis direction, with the benzene rings interdigitated.

In the crystal structure of the title compound, K + ÁC 6 H 4 IO 3 S À Á-H 2 O, the potasium cation is 2.693 (3)-2.933 (3) Å from the sulfonate and water O atoms (including symmetry-related atoms) and forms a two-dimensional sheet-like structure in the bc plane, with the iodobenzene rings protruding above and below. The water molecule of crystallization is hydrogenbonded to sulfonate O atoms within this two-dimensional arrangement. Symmetry-related iodobenzene rings are arranged perpendicular to one another with the I atom ca 4.1 Å from the centroid of the neighbouring benzene ring. In the crystal structure, these two-dimensional sheet-like supramolecular structures are arranged parallel to one another, stacked along the a-axis direction, with the benzene rings interdigitated.
Symmetry related iodobenzene rings are arranged perpendicular to one another, with the iodine atom ca 4.1 Å from the centroid of the neighbouring benzene ring (Fig. 3). The water molecule of crystallization is hydrogen bonded to sulfonate O-atoms (one normal interaction to atom O1, and one rather long interaction to atom O3), within this two-dimensional arrangement (Table 1).
In the crystal structure these 2-D sheet-like supermolecular structures are arranged parallel to one another up the a direction, with the benzene rings interdigited (Fig. 3).

Experimental
The title compound was prepared following the method used by Chau & Kice (1977), and suitable crystals for X-ray analysis were obtained from the reaction mixture.

Refinement
The water H-atoms were located from a difference Fourier map and initially refined with distance restraints [O-H = 0.88 (2) Å and H···H = 1.45 (2) Å, with U iso (H) = 1.5U eq (O)]. In the final rounds of refinement they were held fixed. The C-bond H-atoms were included in calculated positions and treated as riding atoms: C-H = 0.93 Å with U iso (H) = 1.2U eq (C). The highest residual density peak, of 1.43 e Å -2 , is ca 0.84 Å from the Iodine atom.

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 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. O1-S1-O2 113.6 (2) C3-C4-H4 120.00 O1-S1-O3 111.9 (2) C5-C4-H4 120.00 O1-S1-C1 106.95 (18) C4-C5-H5 120.00 K1 xi -S1-O1 58.66 (14) C6-C5-H5 120.00