N,N-Dimethylacetamide–4-iodobenzenesulfonic acid–water (1/1/1)

In the title compound, C6H5IO3S·C4H9NO·H2O, N,N-dimethylacetamide and 4-iodobenzenesulfonic acidmolecules are linked by an intramolecular C—H⋯O hydrogen bond. In the crystal structure, intermolecular O—H⋯O, O—H⋯I and C—H⋯O hydrogen bonds link the molecules.


Related literature
For a related structure, see: Wu et al. (2000). For bond-length data, see: Allen et al. (1987).

Comment
The crystal structure of the title compound with a comb-like structure illustrate the three different components linked by weak interactions based on hydrogen bonds. Furthermore, the hydrolysis mechanism of the innersalt, which was formed from 4-iodobenzenesulfonyl chloride and N,N-dimethylacetamide, was understood (Wu et al., 2000). Meanwhile, the complicated hydrolysate was finally confirmed. We report herein its crystal structure.
The asymmetric unit of the title compound contains N,N-dimethylacetamide, 4-iodobenzenesulfonic acid and water molecules ( Fig. 1), in which the bond lengths (Allen et al., 1987) and angles are within normal ranges. Ring A (C1-C6) is, of course, planar. The intramolecular C-H···O hydrogen bonds (Table 1)  In the crystal structure, intermolecular O-H···O, O-H···I and C-H···O hydrogen bonds link the molecules (Fig. 2), in which they may be effective in the stabilization of the structure. As can be seen from the packing diagram (Fig. 3), the molecules are stacked along the b axis. The comb-like structure depends on C-H···O hydrogen bonds. The 4-iodobenzenesulfonic acid molecules constitute the main chain and the N,N-dimethylacetamide molecules intermesh to each other as the branches.

Experimental
Addition of N,N-dimethylacetamide (1.8 ml, 0.02 mol) into 4-iodobenzenesulfonyl chloride (6.1 g, 0.02 mol) gave milkwhite solution of innersalt (Wu et al., 2000). The innersalt was dissolved in acetone (20 ml) and placed in moist chamber to crystallize. The crystals were obtained by evaporating solvent slowly at room temperature for about 40 d.

Refinement
Water H atoms were located in difference syntheses and refined as [O-H = 0.88 (9) Å and 0.94 (9)     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.