Crystal structure of the salt bis(triethanolamine-κ4 N,O,O′,O′′)cadmium bis[2-(2-oxo-2,3-dihydro-1,3-benzothiazol-3-yl)acetate]

The complex cation of the title salt, [Cd(C6H15NO3)2](C9H6NO3S)2, has a CdII atom coordinated in a bicapped trigonal–prismatic fashion by two tetradentate triethanolamine (TEA) ligands. The supramolecular interactions between cations and anions lead to a two-dimensional network structure parallel to (001).


Chemical context
Triethanolamine (TEA) is a potential ligand for the incorporation of metals into metal-ion-containing supramolecular frameworks, and many compounds constructed from TEA have been reported in the last decade (Haukka et al., 2005;Topcu et al., 2001;Ucar et al., 2004). TEA is also used as a corrosion inhibitor in metal-cutting fluids, as a curing agent for epoxy and rubber polymers, adhesives, antistatic agents or as a pharmaceutical intermediate and an ointment emulsifier. However, TEA has no specific physiological effects (Beyer et al., 1983;Knaak et al., 1997), with exception of its low antibacterial action. Benzothiazoles are bicyclic ring systems and their derivatives have been studied and found to have various chemical reactivities and biological activities. For example, benzothiazole is a precursor for rubber accelerators, a component of cyanine dyes, is used as a slimicide in the paper and pulp industry, or in the production of certain fungicides, herbicides, pharmaceuticals (Bellavia et al., 2000;Seo et al., 2000), anti-allergic (Musser et al., 1984), antitumor (Yoshida et al., 2005) or anti-diabetic (Pattan et al., 2005) substances.

Supramolecular features
In the crystal structure of (I), classical intermolecular O-HÁ Á ÁO hydrogen bonds are observed (Table 1) which link the complex cations and NBTA À anions into a chain structure extending parallel to [110], whereby each cation is surrounded by four NBTA À anions. The H atoms of all hydroxyl groups of the TEA ligands form a hydrogen bond with a carboxylate O atom of the NBTA À ions. In addition, there is weak hydrogen bond between one -CH 2 group and the O1 atom of the NBTA anion, with a CÁ Á ÁO distance of 3.282 (6)Å (Table 1). The above-mentioned hydrogen bonds give rise to R 2 2 (8), R 2 4 (12) and R 4 4 (16) graph-set motifs (Fig. 2). The NBTA À anion layers are not linked by hydrogen bonds, but there are mutualstacking interactions between benzene rings (centroid Cg1) and thiazoline rings (centroid Cg2) of adjacent inversionrelated molecules [Cg1Á Á ÁCg2 (2 À x, Ày, 1 À z) = 3.604 (2) Å ] (Fig. 3). Together, these supramolecular interactions generate a double-layer polymeric network parallel to (001).

Figure 2
Part of the crystal structure with hydrogen bonds shown as dashed lines. For clarity, H atoms not involved in hydrogen bonding are omitted.

Database survey
A survey of the Cambridge Structural Database (CSD; Groom & Allen, 2014) showed that coordination complexes of TEA with many metals including those of the s-, d-, p-, and f-block elements have been reported. Structures containing the [Cd(TEA) 2 ] 2+ cation are deposited in the CSD with reference codes EYIPAD, MEVQIN and YOVBIU.

Synthesis and crystallization
To an aqueous solution (2.5 ml) of Cd(CH 3 OO) 2 (0.103 g, 0.5 mmol) was slowly added an ethanolic solution (5 ml

Refinement details
Crystal data, data collection and structure refinement details are summarized in Table 2. The hydroxyl H atoms of the TEA ligands were located in a difference-Fourier map and were refined with soft O-H distance restraints of 0.87 Å . The Cbound hydrogen atoms were placed in calculated positions and refined as riding atoms with C-H = 0.93 and 0.97 Å for aromatic and methylene hydrogen atoms, respectively, and with U iso (H) = 1.2U eq (C).   (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008) and Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Bis(triethanolamine-κ 4 N,O,O′,O′′)cadmium bis[2-(2-oxo-2,3-dihydro-1,3-benzothiazol-3-yl)acetate]
Crystal data  (13) Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. 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.