Synthesis, characterization and thermal studies of dinuclear adducts of diorganotin(IV) dichlorides with nickel(II) Schiff-base complexes in chloroform

The curious cases of tetrahydrosalen-type ligands interacting with Ni(II): structures and ligand-based oxidation reactions

This work centers around the nickel complexes derived from two tetrahydrosalen-type proligands: N,N'-bis(2-hydroxybenzyl)-o-phenylenediamine (H2salophan) and N,N'-bis(2-hydroxy-3-methylbenzyl)-o-phenylenediamine (H2salophan_Me). The reaction of H2salophan with Ni(OAc)2·4H2O generates a dinuclear complex Ni2(Hsalophan)2(OAc)2 or Na[Ni2(salophan)2(OAc)] when NaOH is added to assist ligand deprotonation. The reaction of H2salophan_Me with Ni(OAc)2·4H2O, however, yields a mononuclear complex Ni(Hsalophan_Me)2. Unlike the corresponding salen-type nickel complexes, these tetrahydrosalen-type complexes are paramagentic and air sensitive (in solution). Oxidation by O2 or peroxides results in dehydrogenation of the ligand backbone to form the salen-type complexes.

Four coordinate tin complexes: synthesis, characterization, thermodynamic and theoretical calculations

In this work, two new Sn(IV) complexes, [SnL(x)]Cl2 where (L(x))(2-) is the deprotonated form of 5-A-salabza-H2=N,N'-bis(salicylidene)-2-aminobenzylamine and A=5-OMe, 5-H, 5-NO2, 5-Br, were synthesized and fully characterized by UV-Vis, FT-IR, (1)H NMR, (13)C NMR, (119)Sn NMR spectroscopies, mass spectrometry and elemental analysis. The thermodynamic formation constants of the complexes were determined spectrophotometrically at 25 °C in acetonitrile. The trend of formation constants of the complexes are as: 5-OMe>5-H>5-NO2>5-Br and Ph2SnCl2>Me2SnCl2>n-Bu2SnCl2. DFT/B3LYP molecular orbital calculations were carried out for the 5-H substituent isomer, [SnL(2)](2+), in an attempt to explain the structure of complexes. The optimized resulting geometries, vibrational frequencies and the NMR resonances of the complexes are discussed.