cis-Triaqua[1,1′-(propane-1,3-diyl)bis(pyridin-1-ium-4-carboxylato)-κO]bis(thiocyanato-κN)manganese(II) dihydrate

In the title compound, [Mn(NCS)2(C15H14N2O4)(H2O)3]·2H2O, the metal ion is octahedrally coordinated by three water molecules, one carboxylate O atom from a 1,1′-(propane-1,3-diyl)bis(pyridinium-4-carboxylate) ligand and two N atoms from two thiocyanate anions in cis positions, forming a mononuclear complex molecule. In the crystal, molecules are connected into a three-dimensional architecture through O—H⋯O hydrogen bonds involving water molecules and carboxylate groups.


Comment
The double betaine 1,3-bis(pyridinium-4-carboxylato)propane is a neutral dicarboxylate ligand. In recent years, an increasing number of coordination compounds with this ligand have been reported (Jiang et al., 2006;Li et al., 2007;Wu et al., 2006;Zhang et al., 2002). The structure of the title compound consists of the mononuclear complex molecules [Mn(C 15 O 4 N 2 H 14 )(NCS) 2 (H 2 O) 3 ] and lattice water molecules. The metal ion adopts an octahedral coordination geometry completed by three water molecules (O5, O6 and O7), a carboxylato O atom (O1) from the betaine ligand, and two N atoms (N1 and N2) from two thiocyanato anions in cis position (Fig. 1). There is a lot of intermolecular O-H···O hydrogen bonds involving the carboxylate groups and water molecules. The O5 water molecule forms two hydrogen bonds with uncoordinated carboxylate oxygen atoms (O3) from different complex molecules, the O6 water molecule contributes its hydrogen atoms to two lattice water molecules (O8 and O9), and the O6 water molecule forms two hydrogen bonds with the coordinated O1 atom and a lattice water molecule (O8). The lattice water molecules are fourcoordinated: they accept hydrogen atoms from coordinated water molecules and contribute their hydrogen atoms to carboxylate oxygen atoms (O4 and O2) or water molecules. These hydrogen bonds lead to a three-dimensional architecture (Fig. 2). In addition, there is a short S···S contact [S1···S2(1 -x, 1 -y, 1 -z), 3.625 (1) Å] between the thiocyanato ions from neighboring complex molecules.

Experimental
The preparation of the compound: 1,3-bis(pyridinium-4-carboxylato)propane (0.029 g, 0.10 mmol) and Potassium thiocyanate (0.039 g, 0.40 mmol) dissolved in ethanol (3 ml) and water (5 ml) were added into the ethanol solution of manganese(II) dichloride hexahydrate (0.040 g, 0.2 mmol),and the resulting light yellow solution was stirred for several minutes, filtered. The filtrate was kept at room temprature, and a few days later,light yellow single crystals suitable for Xray diffraction was obtained.

Refinement
All hydrogen atoms attached to carbon atoms were placed geometrically at calculated positions and refined using the riding model with secondary C-H = 0.97 Å and aromatic C-H = 0.93 Å and with U iso (H) = 1.2U eq (C). H atoms bonded to O atoms have been refined isotropically with U iso (H) = 1.5U eq (O). In the two non-coordinating water molecules the O-H distances were restrained to 0.85 (2)Å and the H···H distances to 1.38 (2)Å.

Figure 1
The structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen atoms are omitted.

Figure 2
View of the intermolecular interactions in the title compound. Hydrogen bonds and S···S contacts are drawn with dashed lines. Hydrogen atoms attached to C atoms are omitted.

cis-Triaqua[1,1′-(propane-1,3-diyl)bis(pyridin-1-ium-4-carboxylato)-κO]bis(thiocyanato-κN)manganese(II)
dihydrate Crystal data 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 > σ(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