Crystal structure of di-μ-benzato-κ4O:O′-bis­[aqua­(benzato-κO)(benzato-κ2O,O′)(2,2′:6′,2′′-terpyridine-κ3N,N′,N′′)europium(III)]–benzoic acid (1/2)

The title compound, [Eu2(C7H5O2)6(C15H11N3)2(H2O)2]·2C7H6O2, is a co-crystalline compound containing a dinuclear EuIII coordination complex with inversion symmetry co-crystallized with benzoic acid in a 1:2 ratio. The Eu3+ ions within the dimer are nine-coordinate, containing one tridentate terpyridine, one water, and four benzoate ions, two of which bridge the Eu3+ ions. Of the four benzoate ligands coordinating to each Eu3+ 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 Eu3+ 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.