cis-Dichloridobis(5,5′-dimethyl-2,2′-bipyridine)manganese(II) 2.5-hydrate

The metal site in the title compound [MnCl2(C12H12N2)2]·2.5H2O has a distorted octahedral geometry, coordinated by four N atoms of two 5,5′-dimethyl-2,2′-dipyridine ligands and two Cl atoms. Two and a half water molecules of hydration per complex unit are observed in the crystal structure. The compounds extend along the c axis with O—H⋯Cl, O—H⋯O, C—H⋯Cl and C—H⋯O hydrogen bonds and π–π interactions [centroid-centroid distance = 3.70 (2) Å] contributing substantially to the crystal packing. The Mn and one of the water O atoms, the latter being half-occupied, are located on special positions, in this case a rotation axis of order 2.

The molecular structure of the complex unit of the titlecompound [Mn(C 12 H 12 N 2 ) 2 Cl 2 ] × 2.5 H 2 O is shown in Figure 1.
The metal site is coordinated by four nitrogen atoms N1, N2, N1 i and N2 i of the ligand dmdpy and two chlorides Cl1 and Cl1 i adopting a distorted octahedral geometry as evidenced by the Mn-N1 distances (2.3111 (19) Å),  (2) Å) and Mn-Cl1 (2.4702 (6) Å). The Mn atom is located in a special position, which in this case is a rotation axis of order 2.
The compound crystallizes in the monoclinic system and its unit cell is shown in Figure 2. The compound [Mn(C 12 H 12 N 2 ) 2 Cl 2 ] × 2.5 H 2 O is a complex that stretches along the crystallographic c axis with the molecular entities being interconnected by weak hydrogen bonds (Desiraju, 1996;Calhorda, 2000) shown in Figure 2. These hydrogen bonds are formed by the interaction between oxygen atoms of water molecules O1 and O2 and the chlorine atom Cl1 which is coordinated to the metal. The distances O1-O2 and O1-Cl1 charge 2.951 (6) Å and 3.243 (3) Å, respectively. π-π interactions between aromatic rings of the nitrogen ligand dmdpy are also shown in Figure 2. These interactions contribute substantially to the crystal packing (Janiak, 2000). In this compound the centroid-centroid distance is 3.70 (2) Å, and there was a substantial overlap between the aromatic rings of the ligand dmdpy, being centroid-plane distance of 3.45 (1)Å and the horizontal displacement of 1.37 (2) Å.

Experimental
All chemicals were obtained commercially and used without further purification. The complex was synthesized by mixing of 0.38 mmol of dmdpy dissolved in ethanol and 0.38 mmol of MnCl 2 × 4 H 2 O dissolved in water. The mixture was placed under agitation for 40 h. After a few weeks, yellow single crystals suitable for the analysis of X-ray diffraction were obtained (yield: 39%).

Refinement
H atoms were positioned geometrically and refined using the riding model approximation with C-H = 0.95 Å, and U iso (H) was refined in group. H atoms of water molecule were located from electron density map, fixed in these positions and assigned the same isotropic displacement parameters for all H atoms. Fig. 1. Molecular structure of the complex unit of the title compound [Mn(C 12 H 12 N 2 ) 2 Cl 2 ] × 2.5 H 2 O. Water molecules were omitted for better visualization. Symmetry code: i (1 -x, y, 1/ 2 -z).  [Mn(C 12 H 12 N 2 ) 2 Cl 2 ] × 2.5 H 2 O (z = 4), hydrogen bonds chain extending along the c axis and π-π interactions between the rings aromatic ligand dmdpy are depicted as dashed lines.