Redetermination of [Pr(NO₃)₃(H₂O)₄]·2H₂O.

The structure of the title compound, tetra-aqua-tris-(nitrato-κ²O,O')praseodymium(III) dihydrate, was redetermined. The structure models derived from the previous determinations [Rumanova et al. (1964 ▶). Kristallografiya, 9, 642-654; Fuller & Jacobson (1976 ▶). Cryst. Struct. Commun.5, 349-352] were confirmed, but now with all H atoms unambiguously located, revealing a complex O-H⋯O hydrogen-bonding network, extending throughout the whole structure. In the title compound, the coordination environment of the Pr(III) atom can best be described as a distorted bicapped square anti-prism defined by three bidentate nitrate anions and four water mol-ecules. Additionally, two lattice water mol-ecules are observed in the crystal packing. The title compound is isotypic with several other lanthanide-containing nitrate analogues.