Crystal structure of bis(1,10-phenanthroline-κ2 N,N′)(1,3-thiazole-2-thiolato-κ2 S 2,N)nickel(II) hexafluoridophosphate 1,4-dioxane sesquisolvate

2-Mercaptothiazolate is generally used as a monodentate and bridging ligand. We report here the crystal structure of a new type of nickel(II) complex in which the 2-mercaptothiazolate ligand acts as a chelating and non-bridging ligand.


Chemical context
2-Mercaptothiazolate (tzS) has three types of atoms available for coordination, namely the thiazolyl N, the thiazolyl S, and the thiolate S atom. Hence the tzS ligand is able to show different coordination modes. The anionic tzS ligand and its protonated neutral form are generally used as bridging ligands [ 2 -tzS-(N, thiolate S)] or as monodentate ligands [(thiolate S)] (Raper et al., 1989(Raper et al., , 1990a whereas transition metal complexes with tzS in a bidentate coordination mode are rare (Raper et al., 1989), although a number of transition metal complexes with 2-mercaptobenzothiazolate as a bidentate ligand exist (Raper et al., 1990b;Ballester et al., 1994;Khan et al., 2010).

Structural commentary
The title salt consists of a complex cation [Ni(tzS)(phen) 2 ] + , one PF 6 À counter-anion, and 1.5 1,4-dioxane solvent mol-ecules of crystallization (one located about a centre of inversion), as shown in Fig. 1. The nickel(II) atom exhibits a considerably distorted octahedral N 5 S coordination environment, which is constructed from one bidentate tzS and two bidentate phen ligands whereby the tzS ligand chelates to the Ni II atom through the thiazolyl N and thiolate S atoms. Selected bond lengths and angles are gathered in Table 1. These values are very similar to that of related Ni complexes with bidentate 2-mercaptobenzothiazolate ligands (Raper et al., 1990b;Ballester et al., 1994;Khan et al., 2010). The narrow bite angle involving the tzS ligand (Table 1) is due to formation of a four-membered chelate ring. The averaged Ni-N(phen) distances and bite angles are 2.08 Å and 80.2 , which are typical values for Ni-phen complexes (Bouzaid et al., 2012).

Figure 1
The structures of the molecular entities in the title salt, shown with 50% probability displacement ellipsoids. [Symmetry code: (i) 1 À x, Ày, 1 À z.] (X = O, F) hydrogen-bonding interactions involving the PF 6 À counter-anion and 1,4-dioxane solvent molecules, which results in the formation of a sheet structure parallel to the ac plane ( Fig. 3, Table 2).

Synthesis and crystallization
The title compound was synthesized using [NiCl 2 (phen)], prepared by a literature protocol (Yakhvarov et al., 2007). A mixture of 2-mercaptothiazole (8.07 Â 10 À4 mol) and one equivalent of Et 3 N in methanol (10 ml) was added slowly to a solution of [NiCl 2 (phen)] (8.07 Â 10 À4 mol) in methanol (20 ml). After stirring overnight, the colour of the solution turned from blue to brown-yellow. 10 equivalents of NH 4 PF 6 were added to the solution, resulting in a pale-brown-yellow precipitate. The precipitate was filtered off and dried in vacuo.
The crude product containing excess NH 4 PF 6 was purified by recrystallization using 1,4-dioxane vapor diffusion into an acetonitrile solution of the crude product. The title complex was isolated as brown block-like crystals [yield 365 mg, 40.6% (based on Ni)].

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3. H atoms were placed in calculated positions and refined as riding, with phenyl C-H = 0.95 Å and methylene C-H = 0.99 Å , both with U iso (H) = 1.2U eq (C).  (Macrae et al., 2006) and Yadokari-XG (Kabuto et al., 2009;Wakita, 2001); software used to prepare material for publication: Yadokari-XG (Kabuto et al., 2009;Wakita, 2001), PLATON (Spek, 2009) and publCIF (Westrip, 2010). Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.