Crystal structure of di-μ-benzato-κ(4) O:O′-bis­[aqua­(benzato-κO)(benzato-κ(2) O,O′)(2,2′:6′,2′′-terpyridine-κ(3) N,N′,N′′)europium(III)]–benzoic acid (1/2)

The title compound, [Eu(2)(C(7)H(5)O(2))(6)(C(15)H(11)N(3))(2)(H(2)O)(2)]·2C(7)H(6)O(2), is a co-crystalline compound containing a dinuclear Eu(III) coordination complex with inversion symmetry co-crystallized with benzoic acid in a 1:2 ratio. The Eu(3+) ions within the dimer are nine-coordinate, containing one tridentate terpyridine, one water, and four benzoate ions, two of which bridge the Eu(3+) ions. Of the four benzoate ligands coordinating to each Eu(3+) position, three distinct coordination modes [monodentate, bidentate–chelating, and bidentate–bridging (twice)] are observed. Within the crystal, there are two additional uncoordinating benzoic acid mol­ecules per dinuclear complex. Within the dimer, the water bound to each Eu(3+) ion participates in intra­molecular hydrogen bonding with a coordinating benzoate. Additionally, the carb­oxy­lic acid group on the benzoic acid participates in inter­molecular hydrogen bonding with a benzoate ligand bound to the dimer complex.