Poly[μ-aqua-bis(μ5-2,4-dichlorobenzoato)dipotassium]

In the title compound, [K2(C7H3Cl2O2)2(H2O)]n, the potassium salt of 2,4-dichlorobenzoic acid, the repeating unit in the polymeric structure consists of two identical irregular KO6Cl units related by twofold rotational symmetry, linked by a bridging water molecule lying on the twofold axis. The coordination polyhedron about the K+ ion comprises a carboxylate O atom and a Cl-atom donor from a bidentate chelate ligand interaction, four O-atom donors from a doubly bridging bidentate carboxylate O,O′-chelate interaction and the water molecule. A two-dimensional polymeric structure lying parallel to (100) is generated through a series of conjoined cyclic bridges between K+ ions and is stabilized by water–carboxylate O—H⋯O hydrogen-bonding interactions.

In the title compound, [K 2 (C 7 H 3 Cl 2 O 2 ) 2 (H 2 O)] n , the potassium salt of 2,4-dichlorobenzoic acid, the repeating unit in the polymeric structure consists of two identical irregular KO 6 Cl units related by twofold rotational symmetry, linked by a bridging water molecule lying on the twofold axis. The coordination polyhedron about the K + ion comprises a carboxylate O atom and a Cl-atom donor from a bidentate chelate ligand interaction, four O-atom donors from a doubly bridging bidentate carboxylate O,O 0 -chelate interaction and the water molecule. A two-dimensional polymeric structure lying parallel to (100) is generated through a series of conjoined cyclic bridges between K + ions and is stabilized by water-carboxylate O-HÁ Á ÁO hydrogen-bonding interactions.

Experimental
The title compound was synthesized by heating together for 10 minutes, 0.5 mmol of 2,4-dichlorobenzoic acid and 0.5 mmol of K 2 CO 3 in 15 ml of 10% ethanol-water at boiling temperature. Partial room temperature evaporation of the solution gave colourless crystal plates of the title complex from which a specimen was cleaved for the X-ray analysis.

Refinement
Carbon-bound hydrogen atoms were placed in calculated positions [C-H = 0.95 Å] and allowed to ride in the refinement, with U iso (H) = 1.2U eq (C). The hydrogen atom of the coordinating water molecule was located in a difference-Fourier synthesis but was subsequently allowed to ride, with U iso (H) = 1.5U eq (O).

Figure 1
The configuration and atom-numbering scheme for the coordination polyhedron of the title complex, with non-H atoms drawn as 40% probability displacement ellipsoids. The bridging water molecule (O1W) lies on a twofold rotation axis.
For symmetry codes, see: Table 1.

Poly[µ-aqua-bis(µ 5 -2,4-dichlorobenzoato)dipotassium]
Crystal data [K 2 (C 7  Special details Geometry. Bond lengths, 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 R-factors(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.