Crystal structure of the salt bis(triethanolamine-κ3 N,O,O′)cobalt(II) bis[2-(2-oxo-2,3-dihydro-1,3-benzothiazol-3-yl)acetate]

The reaction of 2-(2-oxo-2,3-dihydro-1,3-benzothiazol-3-yl)acetic acid (NBTA) and triethanolamine (TEA) with Co(NO3)2 results in the formation of the title complex. In the complex cation, the CoII ion is octahedrally coordinated by two N,O,O′-tridentate TEA molecules with a facial distribution and the N atoms in a trans arrangement.

The reaction of 2-(2-oxo-2,3-dihydro-1,3-benzothiazol-3-yl)acetic acid (NBTA) and triethanolamine (TEA) with Co(NO 3 ) 2 results in the formation of the title complex, [Co(C 6 H 15 NO 3 ) 2 ](C 9 H 6 NO 3 S) 2 , which is formed as a result of the association of bis(triethanolamine)cobalt(II) and 2-(2-oxo-2,3-dihydro-1,3benzothiazol-3-yl)acetate units. It crystallizes in the monoclinic centrosymmetric space group P2 1 /c, with the Co II ion situated on an inversion centre. In the complex cation, the Co II ion is octahedrally coordinated by two N,O,O 0tridentate TEA molecules with a facial distribution and the N atoms in a trans arrangement. Two ethanol groups of each TEA molecule form two fivemembered chelate rings around the Co II ion, while the third ethanol group does not coordinate to the metal. The free and coordinating hydroxy groups of the TEA molecules are involved in hydrogen bonding with the O atoms of NBTA anions, forming an infinite two-dimensional network extending parallel to the bc plane.

Structural commentary
The molecular structure of compound (I) is shown in Fig. 1. The structure consists of a complex cation and one 2-(2-oxo-2,3-dihydro-1,3-benzothiazol-3-yl)acetate anion. The asymmetric unit contains a half of the cationic moiety because the Co II ion is located on an inversion centre. The cation and anion are linked by an O6-H6Á Á ÁO2 hydrogen bond (Table 1). In the cationic complex, the Co II ion is coordinated by four oxygen and two nitrogen atoms of two ligands. The nitrogen atoms occupy trans positions of the coordination polyhedron. The Co-N bond lengths [2.151 (3) Å ] are equal as a result of symmetry, and the N-Co-N bond angle is 180 . The Co-O distances are 2.097 (2) Å and 2.101 (3) Å . One hydroxy group of each ethanol substituent is not involved in the coordination and is directed away from the coordination centre. The N-Co-O bond angles range from 81.60 (10) to 98.40 (10) and the O-Co-O angles are 89.79 (10) and 90.21 (10) . Thus, the coordination polyhedron of the central atom is a slightly distorted octahedron of the CoN 2 O 4 -type. The thiazoline ring (C1/C6/N1/C7/S1) and the bicyclic benzothiazole unit (N1/S1/ C1-C7) are close to planar, the largest deviations from the least-squares planes being 0.019 (2) and 0.028 (4) Å , respectively. The dihedral angle between the plane of the carboxylate group and the benzothiazole ring system is 85.6 (2) .

Supramolecular features
The crystal structure of (I) contains an intricate network of intermolecular O-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds ( In addition, there is weak hydrogen bond between the -CH 2 group and the non-coordinating hydroxy-O atoms of the TEA ligand, with a CÁ Á ÁO distance of 3.455 (6) Å . The above-mentioned hydrogen bonds give rise to R 4 4 (22) and C 4 4 (22) graph-set motifs. The crystal structure contains layers of hydrogen-bonded cations that are sandwiched between layers of hydrogen-bonded anions. Each layer extends in the bc plane. There is hydrogen bonding within and between these layers. These are arranged along [100] in the sequence ACAÁACAÁACA (where A = anion layer and C = cation layer; Fig The molecular structure of (I), showing the atom-labelling scheme. Unlabelled atoms are generated by the inversion centre. Table 1 Hydrogen-bond geometry (Å , ).  (6)  159 Symmetry codes: (i) x; y À 1; z; (ii) Àx þ 2; Ày þ 1; Àz þ 2; (iii) x; Ày þ 3 2 ; z À 1 2 ; (iv) x; Ày þ 1 2 ; z þ 1 2 .

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

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-blocks have been reported. Structures containing the bis(triethanolamine)cobalt(II) cation are described in the CSD entries with refcodes ASUGEA, IGALOR, WEPLIN.

Synthesis and crystallization
To an aqueous solution (2.5 ml) of Co(NO 3 ) 2 (0.091 g, 0.5 mmol) was added slowly an ethanol solution (5 ml

Refinement details
Crystal data, data collection and structure refinement details are summarized in Table 2 The crystal structure packing of (I). Hydrogen bonds are indicated by black dashed lines andstacking interactions by red dashed lines.  (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Bis(triethanolamine-κ 3 N,O,O′)cobalt(II) bis[2-(2-oxo-2,3-dihydro-1,3-benzothiazol-3-yl)acetate]
Crystal data 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.