Bis(3-acetylpyridine-κN)bis(methanol-κO)bis(thiocyanato-κN)nickel(II)

In the crystal structure of the title compound, [Ni(NCS)2(C7H7NO)2(CH3OH)2], the Ni2+ cations are coordinated by two thiocyanate anions, two 3-acetylpyridine ligands and two methanol molecules within slightly distorted NiN4O2 octahedra. The asymmetric unit consists of one Ni2+ cation, which is located on a center of inversion, as well as one thiocyanate anion, one 3-acetylpyridine ligand and one methanol molecule in general positions. The discrete complexes are linked by two pairs of O—H⋯O hydrogen bonds between the hydroxy H atom and the acetyl O atom into chains along the b axis.


Related literature
For general background information including details on thermal decomposition reactions and magnetic properties of the precursor and -1,3 bridging compounds, see: Nä ther & Greve (2003); Boeckmann & Nä ther (2010Wö hlert et al. (2011). For a description of the Cambridge Structural Database, see: Allen (2002).

Comment
The structure of the title compound was prepared within a project on the synthesis of transition metal coordination polymers containing µ-1,3 bridging thiocyanato anions and neutral N-donor co-ligands by thermal decomposition of suitable precursor compounds with N-terminal bonded anions (Boeckmann & Näther, 2010Wöhlert et al., 2011).
In the preparation of a precursor compound using 3-acetylpyridine as co-ligand crystals of the title compound were obtained and characterized by single crystal x-Ray diffraction.
In the crystal structure the Nickel(II) cations are coordinated by four nitrogen atoms of two terminal N-bonded thiocyanato anions and two terminal bonded 3-acetylpyridine coligands as well as two methanol molecules, all of the related by symmetry into discrete complexes (Fig. 1). The coordination polyhedron of the Ni cations can be described as a slightly distorted octahedra with the Ni cation located on a centre of inversion (Table 1).
The discrete complexes are linked by two pairs of O-H···O hydrogen bonds between the hydroxy H atom and the acetyl O atom into chains, which are elongated in the direction of the crystallographic b axis ( Fig. 2 and Table 2). It must be noted that according to a search in the CCDC database (ConQuest Ver.1.14.2012) (Allen, 2002) coordination compounds based on metal thiocyanates and 3-acetylpyridine are unknown.

Experimental
Nickel thiocyanate and 3-acetylpyridine were purchased from Alfa Aesar. The title compound was prepared by the reaction of 174.9 mg Ni(NCS) 2 (1.00 mmol) and 27.3 µL 3-acetylpyridine (0.25 mmol) in 2 mL methanol at RT in a closed 3 ml snap cap vial. After three days colourless blocks of the title compound were obtained.

Refinement
The C-H H atoms were positioned with idealized geometry and were refined isotropically with U eq (H) = 1.2 U eq (C) for aromatic H atoms (1.5 for methyl H atoms) using a riding model with C-H = 0.95 Å (aromatic) and with C-H = 0.98 Å (methyl). The O-H H atom was located in a difference map, its bond lengths set to ideal values of 0.84 Å and afterwards they were refined using a riding model with U~eq~(H) = 1.5 U~eq~(O)

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. 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 > 2sigma(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.