Poly[[tetra­aqua­di-μ₄-oxalato-μ₂-oxalato-dineo­dymium(III)] dihydrate]

The title compound, {[Nd₂(C₂O₄)₃(H₂O)₄]·2H₂O}_n, was synthesized hydro­thermally in the presence of bis­(carb­oxy­ethyl­germanium) sesquioxide. It is isostructural with the corresponding Pr compound [Yang et al. (2009). Acta Cryst. E65, m1152–m1153]. The Nd³⁺ cation is nine-coordinated and its coordination polyhedron can be described as a distorted tricapped trigonal prism. Two Nd³⁺ ions are connected by two O atoms from two oxalate ions to give a dinuclear Nd₂ unit. The unit is further linked to four others via four oxalate ions yielding a layerparallel to (0-11). The linkages between the layers by neighbouring oxalate anions lead to a three-dimensional framework with channels along the c axis. The coordinating and free water mol­ecules are located in the channels and make contact with each other and the host framework by weak O—H...O hydrogen bonds.