(R)-2-Methylpiperazine-1,4-diium diaquatetrachloridoferrate(II)

In the title salt, (C5H14N2)[FeCl4(H2O)2], the FeII cation is coordinated by four Cl− anions and two water molecules in a distorted octahedral geometry. The piperazine ring adopts a normal chair conformation. Intermolecular N—H⋯Cl, N—H⋯(Cl,Cl) and O—H⋯Cl hydrogen bonding is present in the crystal structure.

In the title salt, (C 5 H 14 N 2 )[FeCl 4 (H 2 O) 2 ], the Fe II cation is coordinated by four Cl À anions and two water molecules in a distorted octahedral geometry. The piperazine ring adopts a normal chair conformation. Intermolecular N-HÁ Á ÁCl, N-HÁ Á Á(Cl,Cl) and O-HÁ Á ÁCl hydrogen bonding is present in the crystal structure.

Comment
Recently much attention has been devoted to hydrogen bonding networks in molecular salts containing metal-chlorido complexes (Brammer et al., 2001;Bremner & Harrison, 2003;Kefi & Nasr, 2005). The crystal structure of piperazinediium tetrachloridozincate(II) has been reported (Sutherland & Harrison, 2009). The construction of new members of this family is an important direction in the development of coordination chemistry. We report here the crystal structure of the title compound.
The crystal structure of the title compound (

Refinement
Water H atoms were located in a difference Fourier map and refined as riding their as found relative positions with U iso (H) = 1.5U eq (O). Other H atoms were placed in calculated positions with C-H = 0.9 or 0.98 and N-H = 0.90 Å, and refined using a riding model, with U iso (H) = 1.2U eq (C,N). Fig. 1. The asymmetric unit of the title compound with atom labels. Displacement ellipsoids were drawn at the 30% probability level Crystal data (C 5  supplementary materials sup-3

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 > σ(F 2 ) is used only for calculating Rfactors(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.