The preparation and physical and chemical properties of a square planar Ni(II) complex [Ni(C11H11NOS)](2) containing a Schiff base ligand derived from 2,4-pentanedione and 2-aminobenzenthiol are reported. This Schiff base ligand has three potential donor atoms. The dinegative ligand of 2-(2-mercaptophenyl)imino-4-pentanone coordinates to Ni(II) as a three dentate ligand. The structure was elucidated on the basis of spectroscopic data (IR, NMR and MS) and elemental analyses. The crystal and molecular structure were also obtained by X-ray single crystal diffraction method. The structure is best described as containing two planar Ni(II) centers in NOS2 coordination environments that share an edge formed by two bridging thiolates. (C) 2002 Elsevier Science B.V. All rights reserved.