Poly[aqua[μ-N′-(carboxymethyl)ethylenediamine-N,N,N′-triacetato]neodymium(III)]

In the title complex, [Nd(C10H13N2O8)(H2O)]n, each NdIII ion is coordinated by six O atoms and two N atoms from one N′-(carboxymethyl)ethylenediamine-N,N,N′-triacetate (edta) ligand and one water molecule, displaying a bicapped trigonal-prismatic geometry. The edta ligands link the neodymium metal centres, forming polymeric chains running along the a axis of the unit cell. These chains are further assembled via intermolecular O—H⋯O hydrogen-bonding interactions into a three-dimensional supramolecular network.

In the title complex, [Nd(C 10 H 13 N 2 O 8 )(H 2 O)] n , each Nd III ion is coordinated by six O atoms and two N atoms from one N 0 -(carboxymethyl)ethylenediamine-N,N,N 0 -triacetate (edta) ligand and one water molecule, displaying a bicapped trigonal-prismatic geometry. The edta ligands link the neodymium metal centres, forming polymeric chains running along the a axis of the unit cell. These chains are further assembled via intermolecular O-HÁ Á ÁO hydrogen-bonding interactions into a three-dimensional supramolecular network.

S1. Comment
Molecular self-assembly of supramolecular architectures has received much attention during recent decades (Zeng et al., 2007;Moulton & Zaworotko, 2001). The structures and properties of such systems depend on the coordination and geometric preferences of both the central metal ions and the bridging building blocks, as well as the influence of weaker non-covalent interactions, such as hydrogen bonds and π-π stacking interactions. Recently, we obtained the title coordination polymer, which was synthesized under hydrothermal conditions. As illustrated in Fig. 1, each Nd III centre is in a bicapped trigonal prismatic geometry, defined by six oxygen and two nitrogen atoms from one ethylene-diamine tetraacetate(edta) ligand and one water molecule. The Nd III ions are linked by edta ligands to form an infinite polymeric chain in the a axis direction (Fig.2), and the adjacent Nd···Nd separations are 4.253 (4) and 6.642 (5) Å, respectively. O-H···O hydrogen bonding (Table 1), involving carboxylate groups of edta ligands and the coordinating water molecules, assemble neighbouring chains to form a three-dimensional supramolecular network motif.

S2. Experimental
A mixture of Nd 2 O 3 (0.168 g; 0.5 mmol), ethylene-diamine tetraacetic acid (0.292 g; 1 mmol), water (10 ml) in the presence of HNO 3 (0.1 mmol) was stirred vigorously for 20 min and then sealed in a Teflon-lined stainless-steel autoclave (15 ml, capacity). The autoclave was heated to and maintained at 433 K for 3 days, and then cooled to room temperature at 5 K h -1 to obtain the colorless block crystals.

S3. Refinement
Water H atoms were tentatively located in difference Fourier maps and were refined with distance restraints of O-H = 0.84 Å and H···H = 1.35 Å, and with U iso (H) = 1.5 U eq (O), and then were treated in riding mode. Carbon-bound H and the carboxylate H4 atoms were placed at calculated positions and were treated as riding on the parent atoms with C-H = 0.97 Å, O4-H4: 0.82 and U iso (H) = 1.2 U eq (parent).  The molecular structure showing the atomic-numbering scheme. Displacement ellipsoids drawn at the 30% probability level. Symmetry codes:

Figure 2
View of an infinite polymeric chain of the title complex.

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.