Aqua(2,2′-diamino-4,4′-bi-1,3-thiazole-κ2 N 3,N 3′)(thiodiacetato-κ3 O,S,O′)nickel(II) monohydrate

In the title compound, [Ni(C4H4O4S)(C6H6N4S2)(H2O)]·H2O, the NiII cation assumes a distorted octahedral coordination geometry formed by a diaminobithiazole (DABT) ligand, a thiodiacetate (TDA) dianion and a coordinated water molecule. The tridentate TDA chelates to the Ni cation in a facial configuration, and both chelating rings display the envelope conformations. The two thiazole rings of the DABT ligand are twisted with respect to each other, making a dihedral angle of 9.96 (9)°. Extensive O—H⋯O, N—H⋯O and weak C—H⋯O hydrogen bonding is present in the crystal structure.


Comment
Transition metal complexes of DABT have shown potential application in some fields, such as the effective inhibitors of DNA synthesis of the tumor cells (Waring, 1981;Fisher et al., 1985). As part of a series of investigations of metal complexes of DABT, the title Ni II complex, (I), was prepared in the laboratory and its X-ray structure is reported here.
The molecular structure of the title compound is shown in Fig. 1. The complex has a distorted octahedral coordination geometry formed by one of DABT, one of TDA and one of coordinated water.
The tridentate TDA chelates to Ni II atom in an envelope configuration. Two carboxyl groups of TDA monodentately coordinate to the Ni II atom. Uncoordinated carboxyl oxygen atoms O22 and O24 are hydrogen bonded to the hydrogen atoms of coordinated water of the neighboring complex molecule, as shown in Fig. 2 and Table 1. Othervize, coordinated carboxyl oxygen atom O1 is hydrogen bonded to the hydrogen atoms of lattice watter molecule of the neighboring complex molecule and within complex respectively. The atom O22 and O24 hydrogen bonnded to amino group of DABT of neighboring complex and lattice water within complex respectively.
The DABT chelates to the Ni II atom with a near coplanar configuration, the angle of two thiazole rings being 9.96 (11)°.

Experimental
The DABT was prepared according to the literature (Erlenmeyer, 1948). An aqueous solution (20 ml) containing DABT (1 mmol) and NiCl 2 (1 mmol) was mixed with an aqueous solution (10 ml) of thiodiacetic acid (1 mmol) and NaOH (2 mmol). The mixture was refluxed for 5 h. The solution was filtered after cooling to room temperature. Green single crystals were obtained from the filtrate after 7 d.

Refinement
H atoms on carbon atoms were placed in calculated positions, with C-H distances = 0.93 Å (thiazole ring), and were included in the final cycles of refinement in riding mode with U iso (H) = 1.2U eq (C). Amino H atoms and water H atoms were located in a difference Fourier map and included in the structure factor calculations with fixed positional, and U iso (H) = 1.2U eq (N) and 1.5U eq (O). Fig. 1. The molecular structure of (I) with 30% probability displacement ellipsoids, dashed lines showing hydrogen bonding. Ni II complex molecules.