Synthesis, characterization and crystal structure studies of nickel(II) complexes with NO donor schiff base ligands

Four complexes of the type [Ni(N-substituted-salicydenaminato) ₂], with bidentate Schiff base ligands (L¹-L⁴), have been synthesized. The complexes were characterized by IR and elemental analysis methods. The solid state structures of three complexes (1-3) were determined by X-ray crystallography. The complexes show mononuclear, four-coordinate, slightly distorted square-planar trans-Ni(N₂O ₂) geometry. The angles around the Ni center deviate slightly from 90° indicating a rectangular distortion. The chelating N-Ni-O angles are larger than 90° whereas the non-chelating N-Ni-O angles are smaller than 90°. The crystallograpic studies indicate that any steric/electronic effects due to CH₃ and Br moieties have had no significant impact on the coordination sphere.