Synthesis and properties of nickel(ii) diiminodithiolate and diiminodisulfide N2S2-type complexes. New complexes with non-innocent ligands
摘要:
The following two groups of nickel(II) diiminodithiolate and diiminodisulfide N2S2-complexes were synthesized for the first time: (1) complexes with complete pi conjugation between all four donor centers, viz., compounds with non-innocent ligands, and (2) complexes containing a short conjugation system involving only two imino groups of the ligand. The complexes were studied by H-1 NMR, ESR, and UV spectroscopy, mass spectrometry, and electrochemistry. Solutions of glyoxal bis(2-mercaptoanil)nickel(II) in DMF showed an ESR signal, which decreased with time, the processes being accompanied by an analogous change in the intensity of the absorption band at 931 nm. The electrochemical properties of this complex also change with time. The results of studies demonstrated that compounds with non-innocent ligands of this type were initially generated as classical diiminodithiolate structures, which were transformed into the ortho-iminothioserniquitionate biradicals and then into oligomeric complexes both in solution (fast transformation) and in the solid state (slow transformation). Oligomeric structures of these compounds are stable for a long period of time.