Tetra­kis(1,10-phenanthroline)bis­(μ-pyridine-2,6-dicarboxyl­ato)(pyridine-2,6-di­carboxyl­ato)dicopper(II)terbium(III) nitrate tetra­hydrate

The asymmetric unit of the title compound, [Cu(2)Tb(C(7)H(3)NO(4))(3)(C(12)H(8)N(2))(4)]NO(3)·4H(2)O, consists of one-half of the C (2)-symmetric trinuclear coordination cation, one-half of the C (2)-symmetric nitrate anion and two water mol­ecules. In the coordination cation, the Cu(II) atom is coordinated by four N atoms from two 1,10-phenanthroline ligands and two O atoms from a bridging–chelating carboxyl­ate group of the pyridine-2,6-dicarboxyl­ate anion, completing a distorted N(4)O(2) octa­hedral coordination environment. The Tb(III) atom, located on a twofold rotation axis, is nine-coordinated by three tridentate pyridine-2,6-dicarboxyl­ate anions forming an N(3)O(6) donor set. The intra­molecular Cu⋯Tb distance of 5.0592 (11) Å indicates weak inter­actions between the Cu(II) and Tb(III) atoms. The coordination cations, nitrate anions and water mol­ecules are connected via O—H⋯O hydrogen bonds into layers parallel to the (001) plane. Moreover, there are extensive π–π stacking inter­actions [centroid–centroid distances = 4.332 (7) and 3.878 (5) Å] between the phenanthroline ligands and between phenanthroline and pyridine-2,6-dicarboxyl­ate ligands.