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 Eu^IIIcoordination 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.