Bis{N-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]glycinato-κ3 O,N,O′}iron(II)

In the title compound, [Fe(C6H12NO5)2], the FeII ion lies on an inversion center and is coordinated by two N atoms and four O atoms from two tridentate N-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]glycine ligands, forming a slightly distorted octahedral coordination environment. In the crystal, O—H⋯O, O—H⋯N and weak C—H⋯O hydrogen bonds link molecules, forming a three-dimensional network.

In the title compound, [Fe(C 6 H 12 NO 5 ) 2 ], the Fe II ion lies on an inversion center and is coordinated by two N atoms and four O atoms from two tridentate N-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]glycine ligands, forming a slightly distorted octahedral coordination environment. In the crystal, O-HÁ Á ÁO, O-HÁ Á ÁN and weak C-HÁ Á ÁO hydrogen bonds link molecules, forming a three-dimensional network.

Comment
Tripodal alcohols have been used as poly-dentate ligands in combination with paramagnetic 3d transition metal ions leading to the formation of high nuclear clusters since the discovery of the phenomenon of single-molecule magnetism (Brechin, 2005;Murugesu et al., 2005;Pilawa et al., 1998). During our synthesis to form a poly-nuclear cluster using the N-[tris(hydroxymethyl)ethyl]glycine ligand the title compound was fortuitously obtained.
In the title molecule the Fe II ion is located on an inversion center (Fig. 1). The Fe II ion is in a slightly distorted  (Table 1) connect the molecules into a three-dimensional superamolecular architecture.

Refinement
Hydrogen atoms bonded to N and O atoms were located in a difference map and refined with distance restraints of O-H = 0.84 (2)   The molecular structure of the title compound showing 50% displacement ellipsoids. Unlabeled atoms are related by the symmetry operator (-x+1, -y+1, -z+1).

Crystal data
[Fe(C 6 H 12 NO 5 ) 2 ] M r = 412.18 Monoclinic, P2 1 /c Hall symbol: -P 2ybc a = 8.8198 (7) Å b = 9.0245 (7) Å c = 12.3533 (7)  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.46 e Å −3 Δρ min = −0.39 e Å −3 Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 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.