Crystal structure of a binuclear nickel(II) complex constructed of 1H-imidazo[4,5-f][1,10]phenanthroline and doubly deprotonated benzene-1,3,5-tri­carb­oxy­lic acid

The title complex, [Ni2(C9H4O6)2(C13H8N4)2(H2O)4]·2H2O, bis-(μ-5-carb-oxy-benzene-1,3-di-carboxyl-ato-κ(2) O (1):O (1'))bis-[di-aqua(1H-imidazo[4,5-f][1,10]phenanthroline-κ(2) N (7),N (8))nickel(II)] di-hydrate, was obtained under solvothermal conditions by the reaction of benzene-1,3,5-tricarboxylic acid (H3BTC) with Ni(NO3)2 in the presence of 1H-imidazo[4,5-f][1,10]phenanthroline (IP). The crystal has triclinic (P-1) symmetry with a centrosymmetric binuclear nickel(II) cluster. The Ni(II) atom is coordinated by two N atoms from a chelating 1H-imidazo[4,5-f][1,10]phenanthroline ligand, two carboxyl-ate O atoms from two 5-carb-oxy-benzene-1,3-di-carboxyl-ate ligands and two water mol-ecules in a slightly distorted octa-hedral geometry. Two carboxyl-ate groups bridge two Ni(II) cations, forming the binuclear complex. Extensive N-H⋯O, O-H⋯O and O-H⋯N hydrogen bonding is present in the crystal structure, forming a three-dimensional supermolecular framework. Weak π-π stacking is observed between parallel HBTC(2-) and IP ring systems, the face-to-face separation being 3.695 (2) Å.