Crystal structure of a zigzag CoII coordination polymer: catena-poly[[dichloridobis(methanol-κO)cobalt(II)]-μ-bis(pyridin-3-ylmethyl)sulfane-κ2 N:N′]

In the title compound, each CoII ion is coordinated by two pyridine N atoms from two individual dipyridyl ligands, two methanol O atoms and two chloride anions in an elongated octahedral geometry. Each dipyridyl ligand links two CoII ions, forming infinite zigzag chains.

Reaction of bis(pyridin-3-ylmethyl)sulfane (L) with cobalt(II) chloride in methanol led to the formation of the title coordination polymer, [CoCl 2 (C 12 H 12 N 2 S)(CH 3 OH) 2 ] n , in which the Co II cation lies on a crystallographic inversion centre and the S atom of the L ligand lies on a twofold rotation axis. Each Co II ion is coordinated by two pyridine N atoms from two bridging L ligands, two O atoms from methanol molecules and two chloride anions, all inversion-related. The complex unit has an elongated octahedral geometry, in which N 2 O 2 donor atoms occupy the equatorial positions and two chloride anions occupy the axial positions. Each L ligand links two Co II ions, forming an infinite zigzag chain propagating along the c-axis direction and further stabilized by O-HÁ Á ÁCl hydrogen bonds between the methanol molecules and the chloride anions. Adjacent chains in the structure are connected by intermolecular C-HÁ Á ÁCl hydrogen bonds, resulting in the formation of a three-dimensional supramolecular architecture.

Chemical context
Up to now, large numbers of metal-organic coordination polymers with intriguing topologies and attractive properties have been constructed in which dipyridyl-type molecules functioning as bridging ligands have mainly been used (Leong & Vittal, 2011;Wang et al., 2012;Liu et al., 2011). Our group has also investigated several metal-organic coordination polymers with interesting topologies using such dipyridyl-type ligands (Moon et al., 2011(Moon et al., , 2016Lee et al., 2015;Ju et al., 2014;Im et al., 2017). In an extension of our research in this area, the title compound was prepared by the reaction of cobalt(II) chloride with bis(pyridin-3-ylmethyl)sulfane, C 12 H 12 N 2 S, (L) as a flexible dipyridyl-type ligand [synthesized according to a literature procedure (Park et al., 2010;Lee et al., 2012)]. Our group has previously reported the crystal structure of a looped-chain Co II coordination polymer obtained through the reaction of cobalt(II) nitrate with L ( Moon et al., 2017). In this article, we describe the crystal structure of the title compound, [Co(L)(CH 3 OH) 2 Cl 2 ] n , with L = (pyridin-3-ylmethyl)sulfane, which adopts a one-dimensional zigzag topology.

Structural commentary
As shown in Figs. 1 and 2, the molecular structure of the title compound is generated by the combination of inversion and twofold rotation symmetries. Each Co II cation lies on a crystallographic inversion centre, and the twofold rotation axis passes through the S atom of the L ligand. Therefore, the asymmetric unit comprises one half of a Co II cation, one half of an L ligand, one chloride anion and one methanol molecule. The coordination geometry of the Co II ion is elongated octahedral with the four equatorial positions being occupied by two pyridine N atoms from the two symmetry-related L ligands and two O atoms from two symmetry-related methanol molecules, and the two axial positions being occupied by two chlorido ligands (Fig. 1). Selected bond lengths and angles around the Co1 atom are listed in Table 1. The coordination geometry of the title compound is similar to that (Huang et al., 2008).
Each L ligand bridges two Co II ions into an infinite zigzag chain propagating along the c-axis direction (Fig. 2). The separation between the Co II ions through a L ligand in the chain is 6.0595 (11) Å . The flexible thioether segment [C5-C6-S1-C6 iv -C5 iv ; symmetry code: (iv) Àx + 1, y, Àz À 1 2 ] of the L ligand shows a bent arrangement induced by a gauchegauche configuration with a torsion angle of 74.4 (3) for the C5-C6-S1-C6 iv and C6-S1-C6 iv -C5 iv units. This conformation of the L ligand is similar to those in a cyclic dimer-type silver(I) BF 4 complex, [Ag(L)] 2 Á2BF 4 (Seo et al., 2003), and a staircase-type copper(I) iodide coordination polymer, [(CuI) 2 (L)] n (Hanton et al., 2006). The zigzag topology of the chain may be induced by this conformation of the L ligand.

Figure 1
A view of molecular structure of the title compound, showing the geometry around the Co II centre and the atom-numbering scheme [symmetry codes: (iii) Àx + 1, Ày, Àz; (iv) Àx + 1, y, Àz À 1 2 ]. Displacement ellipsoids are drawn at the 50% probability level. H atoms are shown as small spheres of arbitrary radius.

Synthesis and crystallization
The L ligand was synthesized according to a literature method (Park et al., 2010;Lee et al., 2012). Crystals of the title compound were obtained by slow evaporation of a methanol solution of the L ligand with CoCl 2 Á6H 2 O in an 1:1 molar ratio.

Figure 3
The three-dimensional supramolecular network formed through intermolecular C-HÁ Á ÁCl hydrogen bonds (sky-blue dashed lines) between the chains. H atoms not involved in intermolecular interactions have been omitted for clarity.

catena-Poly[[dichloridobis(methanol-κO)cobalt(II)]-µ-bis(pyridin-3-ylmethyl)sulfane-κ 2 N:N′]
Crystal data 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.
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )