Three new Ni(II) complexes, [NiL(NO 2 )(H 2 O)] (1), [Ni 2 L 2 (PhCH 2 COO) 2 (H 2 O)] (2) and [Ni 2 L 2 (N(CN) 2 ) 2 (H 2 O)] (3), have been synthesized using a tridentate Schiff base ligand, 1-[(3-dimethylamino-propylimino)-methyl]-naphthalen-2-ol (HL) and the polyatomic monoanions NO 2 − , PhCH 2 COO − or N(CN) 2 − . All three complexes (1–3) have been characterized by spectral analysis and X-ray crystallography. Structural analyses reveal that complex 1 is mononuclear, in which the Ni(II) ion is in a distorted octahedral environment, coordinated by the deprotonated tridentate Schiff base (L), a chelating nitrite and one water molecule. The structures of both 2 and 3 consist of dinuclear octahedral Ni(II) units with crystallographic C 2 symmetry. In complex 2, two μ 2 -phenoxido and a water molecule bridge the two Ni(II) centers to make the complex a face sharing bioctahedron, whereas in 3 the Ni(II) atoms are bridged by two μ 1,5 -dicyanamide ligands. Variable temperature magnetic susceptibility measurements show the presence of ferromagnetic coupling in complex 2 with J=+26.20cm −1 and antiferromagnetic coupling in complex 3 with J=−1.90cm −1 .