Three unsymmetrical Schiff base ligands H2Ln(n=1,2 and 3) have been synthesized.H2L1 was prepared by reaction from 1∶1∶1 condensation of 1,2-ethanediamine,acetylacetone and salicylaldehyde.H2L2 was prepared by reaction from 1∶1∶1 condensation of acetylacetone,(1R,2R)-diaminocyclohexane and salicylaldehyde.H2L3 was prepared by reaction from 1∶1∶1 condensation of benzoylacetone,1,2-ethanediamine and salicylaldehyde.Three mononuclear complexes 1,2 and 3 were prepared by reaction of three Schiff base ligands(H2Ln) with nickelous acetate respectively.The compounds were characterized by 1H NMR,FTIR,elemental analysis and X-ray diffraction single crystal structure analysis.CCDC: 825874,1;825875,2;825876,3.