Syntheses, characterization and X-ray crystal structures of Ni(II) complexes of tridentate monocondensed and tetradentate dicondensed Schiff bases

Two octahedral complexes [Ni(HL1)2](ClO4)2 (1) and [Ni(HL2)2](ClO4)2 (2) and a square planar complex [Ni(HL3)]ClO4 (3) have been prepared, where [HL1 = 3-(2-amino-ethylimino)-butan-2-one oxime, HL2 = 3-(2-amino-propylimino)butan-2-one oxime] and H2L3 = 3-[2-(3-hydroxy-1-methyl-but-2-enylideneamino)-1-methyl-ethylimino]-butan-2-one oxime. All the complexes have been characterized by elemental analyses, spectral studies and room temperature magnetic moment measurements. The molecular structures of all three compounds were elucidated on the basis of X-ray crystallography; complexes 1 and 2 are seen to be the mer isomers.

The unsymmetrical tetradentate Schiff base ligands involving 1,2-diaminoethane or 1,2-diaminopropane with 2,4-pentanedione and diacetylmonoxime forms square planar complexes with Ni(II) whereas complexes of symmetrical ligands involving the same diamines and diacetylmonoxime cannot be prepared; instead the bis six-coordinate complex of the monocondensed tridentate Schiff bases were produced.Figure optionsDownload as PowerPoint slide