Crystal structure of triaquapotassium 3-carboxy-4-hydroxybenzenesulfonate, K(H2O)3(C7H5SO6)

Abstract

Source of materialTo solution of 5-sulfosalicylic acid dihydrate (0.2865 g, 1.1 mmol), potassium hydroxide solid (0.0730 g, 1.3 mmol) was added. After the sample was stirred for 1 h at 323 K, the solution was filtered. Colorless crystals of the title compound were obtained after the filtered left at room temperature for several days. DiscussionCurrently, the assembly of multidentate ligands with transition metal [1,2] is of great interest due to their great use in constructing two-and three-dimensional polymers with functional properties, such as catalysis [3,4], optical material [5], and gas adsorbents [6]. Although some works have touched with these study [7,8], they mostly recur on the use of transition metal to form such complicated structures. In the present study, potassium has been utilized to construct a three-dimensional polymer structure with the multifunctional ligand 5-sulfosalicylic acid, which has three coordination groups, COH, CO 2H, and CSO3H. Additionally, potassium coordination polymers with even cores are often found in zeolite materials [9]. The crystal structure analysis of the title compound revealed that SO 3 H group is deprotonated, the OH and CO 2 H groups are protonated. The sulfonate group of the 3-carboxy-4-hydroxybenzenesulfonate ion binds to three different potassium ions with the oxygen atoms O1, O1 #1, O2 and the carboxylic group binds to a fourth K + ion through the O6 oxygen atom (#1: x+1,y+1,z). The potassium ions are eight-coordinated by three sulfonate oxygen atoms from three different H 2 Ssal groups, one carboxylic oxygen atom of another H2Ssal group and four water molecules. K + ions are bridged by the two m 2 -O1 atoms of the SO 3 groups and two m 2 -O8 water atoms to form two four-membered rings (K 2 O 2 ). Additionally, the H 2Ssal is connected by O2 to another K + ion (#2: x,y1,z), while the O6 atom of the carboxylic group is linked to a further K + ion (#3: x+2,y+1,z). The equivalent operations #1 and #3 produce chains of K + ions, which are interlinked by a double bridge formed by the O1 atoms and water molecules O8 (O8 #3 ). A polymeric structure is formed by the KO interactions. The K···K intrachain distances are 4.3771 (8)