Bis[mu-2-{bis(2-pyridylethyl)amino}phenolato]bis[aquanickel(II)] dinitrate tetrahydrate

The title complex, [Ni-2(L-O-)(H2O)(2)](NO3)(2).4H(2)O, where L-O- is bis{2-[bis(2-pyridyl)ethyl]amino}phenol (C20H20N3O), is dimeric with each Ni2+ ion coordinated by two bridging phenolate O atoms and three N atoms of the N3O-tetradentate ligand anion L-O-. A molecule of water on each metal completes the octahedral geometry. Crystallographic inversion symmetry is present at the center of the Ni2O2 plane of the dimeric unit.