Crystal structure of di-μ-benzato-κ4 O:O′-bis­[aqua­(benzato-κO)(benzato-κ2 O,O′)(2,2′:6′,2′′-terpyridine-κ3 N,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 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 mol-ecules per dinuclear complex. Within the dimer, the water bound to each Eu(3+) ion participates in intra-molecular hydrogen bonding with a coordinating benzoate. Additionally, the carb-oxy-lic acid group on the benzoic acid participates in inter-molecular hydrogen bonding with a benzoate ligand bound to the dimer complex.