Abstract Five new unsymmetrical Schiff bases containing NNOS coordination sphere and their Ni (II) complexes, NiL X (where X= 1–5, and L 1= methyl-2-{N-[2-(acetone) triflourolidynenitrilo] ethyl} amino-1-cyclopentenedithi-ocarboxylate, L 2= methyl-2-{N-[2- (acetone) ethylidyneni-trilo] ethyl} amino-1-cyclopentenedithiocarboxylate, L 3= methyl-2-{N- [2-(acetone) phenylidy-nenitrilo] ethyl} amino-1-cyclopentenedithiocarboxylate, L 4= ...