μ‐Acetato‐μ‐aqua‐μ‐hydroxido‐bis[(1,10‐phenanthroline)copper(II)] dinitrate monohydrate

The triply bridged title dinuclear copper(II) compound, Cu₂(C₂H₃O₂)(OH)(C₁₂H₈N₂)₂(H₂O)](NO₃)₂·H₂O, (I), consists of a Cu₂(μ₂‐CH₃COO)(μ₂‐OH)(phen)₂(μ₂‐OH₂)]²⁺ cation (phen is 1,10‐phenanthroline), two uncoordinated nitrate anions and one water molecule. The title cation contains a distorted square‐pyramidal arrangement around each metal centre with a CuN₂O₃ chromophore. In the dinuclear unit, both Cu^II ions are linked through a hydroxide bridge and a triatomic bridging carboxylate group, and at the axial positions through a water molecule. The phenanthroline groups in neighbouring dinuclear units interdigitate along the 010] direction, generating several π–π contacts which give rise to planar arrays parallel to (001). These are in turn connected by hydrogen bonds involving the aqua and hydroxide groups as donors with the nitrate anions as acceptors. Comparisons are made with isostructural compounds having similar cationic units but different counter‐ions; the role of hydrogen bonding in the overall three‐dimensional structure and its ultimate effect on the cell dimensions are discussed.