Thermal Decomposition of New Mononuclear NiII Complexes with ONNO Type Reduced Schiff Bases and Pseudo Halogens

Mononuclear nickel(II) complexes were prepared by reaction of the three ONNO type reduced Schiff bases bis-N,N′-(2-hydroxybenzyl)-1,3-propanediamine (LHH2), bis-N,N′-(2-hydroxybenzyl)-2,2′-dimethyl-1,3-propanediamine (LDMHH2), and bis-N,N′-[1-(2-hydroxyphenyl)ethyl]-1,3-propanediamine (LACHH2) with NiII ions in the presence of pseudo halides (OCN–, SCN– and N3–). The complexes were characterized with the use of elemental analyses, IR spectroscopy, and thermal analyses. The molecular structure of one of the complexes was obtained by single-crystal X-ray diffraction. The obtained complexes are mononuclear, and a pseudo halide molecule is attached. One of the oxygen atoms of the ligand is in phenolate and the other was in phenol form. According to the thermogravimetry results, it was thought that the pseudo halide thermally detaches from the structure as hydropseudo halide. In azide-containing complexes an endothermic reaction was observed although the azide group usually decomposes with an exothermic reaction.