Bis(μ-adamantane-1,3-dicarboxyl­ato-κ(4) O (1),O (1′):O (3),O (3′))bis­[aqua­(3-carboxy­adam­antane-1-carboxyl­ato-κO (1))(1,10-phen­an­throline-κ(2) N,N′)erbium(III)] dihydrate

The asymmetric unit of the binuclear centrosymmetric title compound, [Er(2)(C(12)H(14)O(4))(2)(C(12)H(15)O(4))(2)(C(12)H(8)N(2))(2)(H(2)O)(2)]·2H(2)O, contains one Er(III) atom, one coordinated water mol­ecule, one 1,10-phenanthroline (phen) ligand, two differently coordinated adamantane-1,3-dicarboxyl­ate (H(2)L) ligands and one lattice water mol­ecule. The Er(III) ion is eight-coordinated by four O atoms from bridging L (2−), one O atom from HL (−), one O atom from the coordinated water and two N atoms from a phen ligand. Extensive O—H⋯O hydrogen-bonding inter­actions result in the formation of chains which are further linked into a layer-like network by π–π stacking inter­actions centroid–centroid distance = 3.611 (3) Å] between adjacent phen ligands belonging to neighbouring chains. The carboxy group of the HL (−) ligand is equally disordered over two positions.