trans-Tetraaquabis[bis(pyridin-3-yl)methanone-κN]manganese(II) bis(perchlorate)

In the title complex, [Mn(C11H8N2O)2(H2O)4](ClO4)2, the Mn2+ ion is located on an inversion center with the slightly distorted N2O4 octahedral coordination sphere comprising N-atom donors from two monodentate trans-related bis(pyridin-3-yl)methanone ligands and four water ligands. The two perchlorate anions are linked to the mononuclear complex molecule through water O—H⋯O hydrogen bonds while inter-complex water O—H⋯N(pyridine) interactions form an infinite chain structure extending along the b axis. The perchlorate anions also function as inter-unit links through water O—H⋯O hydrogen bonds which, together with water O—H⋯O(carbonyl) interactions, give a three-dimensional framework structure.

In the title complex, [Mn(C 11 H 8 N 2 O) 2 (H 2 O) 4 ](ClO 4 ) 2 , the Mn 2+ ion is located on an inversion center with the slightly distorted N 2 O 4 octahedral coordination sphere comprising Natom donors from two monodentate trans-related bis(pyridin-3-yl)methanone ligands and four water ligands. The two perchlorate anions are linked to the mononuclear complex molecule through water O-HÁ Á ÁO hydrogen bonds while inter-complex water O-HÁ Á ÁN(pyridine) interactions form an infinite chain structure extending along the b axis. The perchlorate anions also function as inter-unit links through water O-HÁ Á ÁO hydrogen bonds which, together with water O-HÁ Á ÁO(carbonyl) interactions, give a three-dimensional framework structure.

Comment
The coordination chemistry of the pyridyl ketone derivatives has attracted much attention due to the angular-shaped C(sp 2 )-CO-C(sp 2 ) moiety and the rotatable C-C σ bonds to the pyridyl groups (Huang et al., 2003;. Recently, we reported the zigzag chain structure of the zinc(II) complex with bis(pyridin-3-yl)methanone (Zhang, 2011). Herein, we report the structure of a new mononuclear complex of this ligand with manganese(II), the title complex [Mn (C 11 H 12 In this complex, the Mn 2+ ion is located on an inversion center with the slightly distorted N 2 O 4 octahedral coordination sphere comprising N-atom donors from two monodentate trans-related bis(pyridine-3-yl)methanone ligands and four water ligands ( Fig. 1). This is significantly different from that found in the polymeric complex [(CuL 2 )(ClO 4 ) 2 ] n [L = bis(pyridin-3-yl)methanone], in which the N 4 O 2 distorted octahedral Cu 2+ center is surrounded by four equatorial pyridyl N-atom donors and two axially related perchlorate O-atoms . In the present structure, the two perchlorate anions are linked to the mononuclear complex moiety through water O2W-H···O4 hydrogen bonds (Table 1) while inter-complex water O1W-H···N1(pyridyl) interactions form an infinite chain structure extending along the b axis (Fig. 2). The perchlorate anions also function as inter-unit links through water O2W-H···O4/O5 hydrogen bonds which with water O1W-H··· O1(carbonyl) interactions give a three-dimensional framework structure.

Experimental
Bis(pyridin-3-yl)methanone was prepared according to the previously reported procedure . The title complex was synthesized by reacting the ligand (19 mg, 0.1 mmol) with Mn(ClO 4 ) 2 . 6H 2 O (36 mg, 0.1 mmol) in 5 ml of methanol followed by the addition of 1 ml of deionized water. The clear solution obtained was stirred at room temperature for three hours, filtered and the filtrate left to slowly evaporate at room temperature. The block-like crystals were deposited after about three weeks (22.9 mg, 66% yield based on the ligand).

Refinement
All H atoms were located in the difference electron density maps but were placed in idealized positions and allowed to ride on the carrier atoms, with C-H = 0.93 Å and with U iso (H) = 1.2U eq (C or 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq