Novel three-dimensional coordination polymers of lanthanides with sulfate and oxydiacetic acid

Three three-dimensional coordination polymers, viz. poly[[diaqua-μ4-oxydiacetato-di-μ4-sulfato-dipraseodymium(III)] hemihydrate], [Pr2(C4H4O5)(SO4)2(H2O)2]·0.5H2O, (I), poly[[diaquadi-μ3-oxydiacetato-μ3-sulfato-dineodymium(III)] 1.32-hydrate], [Nd2(C4H4O5)2(SO4)(H2O)2]·1.32H2O, (II), and poly[[diaquadi-μ3-oxydiacetato-μ3-sulfato-disamarium(III)] 1.32-hydrate], [Sm2(C4H4O5)2(SO4)(H2O)2]·1.32H2O, (III), were obtained by hydrothermal reactions of the respective lanthanide oxides and ZnSO4 with oxydiacetic acid (odaH2). The Nd(3+) and Sm(3+) compounds form isomorphous crystal structures in which the lanthanide cations are nine-coordinate, having a tricapped trigonal prismatic coordination. The Pr(3+) compound has an entirely different crystal structure in which two types of coordination polyhedra are observed, viz. nine-coordinate (trigonal prism) and ten-coordinate (bicapped square antiprism). The sulfate anions show various coordination modes, one of which has only rarely been observed crystallographically to date.