Synthesis and crystal structure of the neodymium sulfate nitrate trihydrate Nd[SO4][NO3] • 3H2O

Pale violet single crystals of Nd[SO4][NO3] (.) 3H(2)O emerged in a reaction of neodymium nitrate (dissolved in concentrated nitric acid) with H2S which was thereby oxidized to sulfate anions. The title compound crystallizes monoclinically in space group P2(1/m) (a = 630.56(6), b = 692.34(6), c = 898.27(8) pm, beta = 93.305(7)degrees) with two formula units per unit cell. The Nd3+ cations are surrounded by nine oxygen atoms of three sulfate, one nitrate, and three water particles with both the [NO3](-) and one [SO4](2-) anion acting as bidentate chelating ligands which occupy common edges that are situated opposite to each other and form an elongated tetrahedron. The remaining three water molecules and two sulfate anions work just as terminal ligands building a corrugated five-membered ring as waist around this bisphenoid. These polyhedra about the Nd3+ cations are connected via the sulfate tetrahedra to rods along [010] which show a sawtooth-like shape caused by the nitrate triangles and two of the three water molecules attached to neodymium. The chains are packed according to a primitive rod packing with the [NO3](-) anions of one rod pointing towards the [SO4](2-) anions of the adjacent one and vice versa. They are connected to each other by hydrogen bridging bonds between the water molecules and mainly the nitrate triangles.