Diaquabis­(2,5-dihydroxy­benzoato-κO)bis­(1,10-phenanthroline-κ²N,N′)strontium(II) bis­(1,10-phenanthroline) tetra­hydrate

The title compound, [Sr(C₇H₅O₄)₂(C₁₂H₈N₂)₂(H₂O)₂]·2C₁₂H₈N₂·4H₂O, consists of an Sr^II complex, uncoordinated phenanthroline (phen) mol­ecules and solvent water mol­ecules. The Sr^II ion is located on a twofold axis and is coordinated by two phen ligands, two dihydroxy­benzoate anions and two water mol­ecules in a distorted tetra­gonal anti­prismatic geometry. Partially overlapped arrangements exist between parallel coordinated and parallel uncoordinated phen rings; the face-to-face separations between the former (coordinated) and the latter (uncoordinated) rings are 3.436 (13) and 3.550 (14) Å, respectively. This difference suggests the effect of metal coordination on π–π stacking between phen rings.