A nickel(II) fumarate complex with o-phenanthroline

In the dinuclear and centrosymmetric title complex, fumarato-bis[aquabis(1,10-phenanthroline)nickel(II)] fumarate hexadecahydrate, [Ni-2(C4H2O4)(C12H8N2)(4)(H2O)(2)]-(C4H2O4).16H(2)O or [Ni-2(phen)(4)L(H2O)(2)]L.16H(2)O, where phen = 1,10-phenanthroline and L2- = fumarate, the nickel(II) canon is six-coordinated by two O atoms, one from a water molecule and the other from one end of a bridging L2- anion, and four N atoms from two bidentate phen ligands. Each of the two independent L2- anions is located about an inversion centre. Interestingly, one L2- anion is bridging and the other acts as a counter-ion. The [Ni-2(phen)(4)L(H2O)(2)](2+) cations, water molecules and L2- anions are connected through complex hydrogen-bonding interactions to form a three-dimensional structure.