Crystal structure of tetrakis(isonicotinamide-κN)bis(thiocyanato-κN)cobalt(II)–isonicotinamide–ethanol (1/2/1)

The crystal structure of the title compound consists of discrete octahedral cobalt(II) complexes that are linked by a variety of hydrogen-bonding interactions into a three-dimensional network.


Chemical context
There is an increasing interest in compounds showing cooperative magnetic properties, such as ferromagnetism, antiferromagnetism and metamagnetism or a slow relaxation of the magnetization, indicative of single-molecule or singlechain magnetism Ma et al., 2009;Palion-Gazda et al., 2015;Nä ther et al., 2013). In this context we have reported on a number of one-dimensional cobalt(II) thiocyanate coordination compounds with different N-donor coligands that show slow relaxations of the magnetization which in some compounds can be traced back to the behaviour of single-chain magnets (SCM) (Wö hlert et al., 2014;Werner et al., 2014Werner et al., , 2015a. In the course of our systematic investigation of these materials, we became interested in the monodentate ligand isonicotinamide, which can coordinate with the N atom to the Co II atoms, forming the desired onedimensional compounds. However, instead of the expected chain compound, a discrete complex with additional solvate molecules of composition [Co(NCS) 2 (C 6 H 6 N 2 O) 4 ]Á2C 6 H 6 -N 2 OÁC 2 H 5 OH was obtained in the current study and characterized by single-crystal X-ray diffraction.

Figure 2
Crystal structure of the title compound in a view along the a axis. channels, the isonicotinamide solvent molecules are embedded whereas the smaller channels are occupied by the disordered ethanol molecules (Figs. 2 and 3). The solvent molecules are linked by O-HÁ Á ÁO, N-HÁ Á ÁO and N-HÁ Á ÁN hydrogen-bonding interactions to the the isonicotinamide ligands that form the channels. Weak C-HÁ Á ÁO and C-HÁ Á ÁS interactions are also observed, consolidating the packing of the crystal structure.

Database survey
In the Cambridge Structure Database (Version 5.37, last update 2015; Groom et al., 2016) only five structures of coordination compounds with isonicotinamide and thiocyanate as ligands are reported: two clathrates of nickel coordination polymers, in which the metal atoms are connected into chains by -1,3-bridging thiocyanate ligands of which one contains 9,10-anthraquinone and the other pyrene as clathrate molecules (Sekiya et al., 2009). Furthermore, a one-dimensional cadmium 9,10-dichloroanthracene-clathrate with bridging -1,3-thiocyanate ligands between the metal atoms is reported (Sekiya & Nishikiori, 2005), as well as a three-dimensional network consisting of cadmium cations with -1,3-bridging thiocyanate ligands (Yang et al., 2001), and finally one Cu coordination polymer in which Cu-NCS sheets are observed (Ðaković et al., 2010). In this context we have reported recently on a Zn complex in which the Zn cations are tetrahedrally coordinated by two terminal N-bonded thiocyanate anions and two isonicotinamide ligands (Neumann et al., 2016).

Synthesis and crystallization
Cobalt(II) thiocyanate and isonicotinamide were obtained from Alfa Aesar and were used without further purification. Single crystals suitable for structure analysis were obtained by the reaction of 26.3 mg Co(NCS) 2 (0.15 mmol) with 73.3 mg isonicotinamide (0.6 mmol) in ethanol (1.5 ml) after being allowed to stand for a few days at room temperature.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. The C-H, O-H and N-H hydrogen atoms were located in a difference map but were positioned with idealized geometry (methyl and O-H hydrogen atoms were allowed to rotate but not to tip) and were refined with U iso (H) = 1.2U eq (C,N) (1.5 for methyl and O-H hydrogen atoms) using a riding model with C-H = 0.95 Å for aromatic, C-H = 0.98 Å for methyl, N-H = 0.88 Å and O-H = 0.84 Å , respectively. The ethanol molecule was found to be disordered over two sets of sites and was refined with fixed occupation factors of 0.6 and 0.4, respectively.

Figure 3
Crystal structure of the title compound in a view along the b axis. Intermolecular hydrogen bonding is shown as dashed lines and the second orientation of the disordered ethanol molecule is omitted for clarity.

Computing details
Data collection: X-AREA (Stoe, 2008); cell refinement: X-AREA (Stoe, 2008); data reduction: X-AREA (Stoe, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: XP in SHELXTL (Sheldrick, 2008) and DIAMOND (Brandenburg, 1999); software used to prepare material for publication: 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.