catena-Poly[[diaquadichloridomanganese(II)]-μ-1,1′-bis(1H-1,2,4-triazol-1-ylmethyl)ferrocene]

In the title complex, [FeMn(C8H8N3)2Cl2(H2O)2]n, the MnII atom, located on an inversion center, is octahedrally coordinated by two N atoms from two adjacent 1,1′-bis(1H-1,2,4-triazol-1-ylmethyl)ferrocene (btmf) ligands and two Cl atoms forming the equatorial plane, with the axial positions occupied by two O atoms of coordinated water molecules. The btmf ligands link adjoining MnII atoms into a zigzag chain along the a axis. The crystal structure is stabilized by intermolecular O—H⋯N hydrogen bonds, which link the chains, forming a two-dimensional layer parallel to (10); O—H⋯Cl interactions link the layers, forming a three-dimensional network.

In the title complex, [FeMn(C 8 H 8 N 3 ) 2 Cl 2 (H 2 O) 2 ] n , the Mn II atom, located on an inversion center, is octahedrally coordinated by two N atoms from two adjacent 1,1 0 -bis(1H-1,2,4-triazol-1-ylmethyl)ferrocene (btmf) ligands and two Cl atoms forming the equatorial plane, with the axial positions occupied by two O atoms of coordinated water molecules. The btmf ligands link adjoining Mn II atoms into a zigzag chain along the a axis. The crystal structure is stabilized by intermolecular O-HÁ Á ÁN hydrogen bonds, which link the chains, forming a two-dimensional layer parallel to (101); O-HÁ Á ÁCl interactions link the layers, forming a three-dimensional network.

Comment
It is well known that ferrocene complexes undergo reversible redox reactions (Li et al., 2003;Togni & Haltermann, 1998;Beer et al., 1992). Moreover, ferrocene-based bidentate ligands are excellent building blocks and used to metal-organic polymers and supramolecular architectures (Gao et al., 2006;He et al., 2008). Recently, we have been employed ferrocenecontaining ligand 1,1'-bis[(1H-1,2,4-triazol-1-yl)methyl]ferrocene(btmf) to construct Co(II) metal-organic polymer (Zhou et al., 2007). Following on from our research work on the coordination chemistry of ferrocene-based bidentate, we focused on the effect of metal ions on the metal-organic polymers. In this paper, we report here the synthesis and crystal structure of the title complex (I).
The Mn II and iron atoms are located on inversion center. Mn II is octahedrally coordinated by two N atoms from two adjacent btmf ligands and two Cl atoms forming the equatorial plane, whereas axial positions are occupied by two O atoms of coordinated water molecules. The distances of Mn-N, Mn-Cl and Mn-O bonds are within normal range. The torsion angle between ferrocene moiety and triazole motif is 62.4 (3)°, which is near to our reported Co II compound (Zhou et al., 2007). Each btmf molecular clips serve as bridge to link two adjacent Mn II centers into a 1D zigzag chain, as shown in Fig.   1. Comparison of {Co(btmf) 2 (CH 3 CH 2 OH)(H 2 O)] ClO 4 ) 2 .3(CH 3 CH 2 OH)} n (Zhou et al., 2007) and the title compound indicates that the metal ions may play critical role in modulating the resulting structure.
The structure is further stabilized by intermolecular O-H···N, O-H···Cl hydrogen bonds (Table. 1). The O-H···N hydrogen bonds links the chains forming a two dimensionnal layer parallel to the (1 0 -1) plane (Fig. 2) whereas the O-H···Cl interactions links these layers to form a thre dimensionnal network.

Refinement
The H atoms of btmf ligand were placed in geometrically idealized positions and constrained to ride on their parent atoms, with C-H distances in the range 0.93-0.98Å, with U iso (H)=1.2U eq (C). The H atoms of water molecules were located in a difference map and refined with restraints of O-H=0.83 (1)Å, and with U iso (H)=1.5U eq (O). The highest peak of residual density is located 1.94Å from C4 atom.

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