Ligand exchange reactions of NiCl2(PPh3)2 with O (S )⌒N⌒S ligands were studied. Oxidation products of O⌒N⌒S ligands have been characterized and their structures determined: 3-methyl-4H-benzo[b] [ 1,4]thiazin-2-yl-phenylmethanone / 2-methyl-benzo[d] [ 1,3]thiazole (mixed crystal); [2-iminoisopropyl-thiophenolato(2-)](triphenyl-phosphane)-nickel(II); 1 -phenyl-3-methyl-4-(benzoyl-thiobenzoylhydrazono)-pyrazol-5-thione; [ 1 -phenyl-3-methyl- 4-(benzoyl-thiobenzoylhydrazono)-pyrazol-5-thionato](triphenyl-phosphane)-nickel(II).