Poly[diaquabis­(μ(4)-fumarato-κ(4) O (1):O (1′):O (4):O (4′))(μ(4)-fumarato-κ(6) O (1):O (1),O (1′):O (4):O (4),O (4′))(μ(2)-fumaric acid-κ(2) O (1):O (4))dipraseodymium(III)]

The title complex, [Pr(2)(C(4)H(2)O(4))(3)(C(4)H(4)O(4))(H(2)O)(2)](n), was synthesized by reaction of praseodymium(III) nitrate hexa­hydrate with fumaric acid in a water–ethanol (4:1) solution. The asymmetric unit comprises a Pr(3+) cation, one and a half fumarate dianions (L (2−)), one half-mol­ecule of fumaric acid (H(2)L) and one coordinated water mol­ecule. The carboxyl­ate groups of the fumarate dianion and fumaric acid exhibit different coordination modes. In one fumarate dianion, two carboxyl­ate groups are chelating with two Pr(3+) cations, and the other two O atoms each coordinate a Pr(3+) cation. Each O atom of the second fumarate dianion binds to a different Pr(3+) cation. The fumaric acid employs one O atom at each end to bridge two Pr(3+) cations. The Pr(3+) cation is coordinated in a distorted tricapped trigonal–prismatic environment by eight O atoms of fumarate dianion or fumaric acid ligands and one water O atom. The PrO(9) coordination polyhedra are edge-shared through one carboxyl­ate O atom and two carboxyl­ate groups, generating infinite praseodymium–oxygen chains, which are further connected by the ligands into a three-dimensional framework. The crystal structure is stabilized by O—H⋯O hydrogen-bond inter­actions between the coordin­ated water mol­ecule and the carboxyl­ate O atoms.