Spectrochemical Properties and Solvatochromism of Tetradentate Schiff Base Complex with Nickel: Calculations and Experiments

Abstract

The nickel(II) complex with a tetradentate Schiff base ligand obtained by condensation of 1,3-propanediamine with salicylaldehyde (H2salpn) was studied in a variety of solvents at room temperature. The product, that is, the N′,N′′-propylenebis(salicylaldiminato)nickel(II) ([Ni(salpn)]) complex, is brown in color in the solid state. The properties of the ligand and complex were characterized by elemental analysis, solubility in common solvents, molar conductivities, and ultraviolet (UV) and visible (Vis) spectroscopy. The [Ni(salpn)] complex is easily soluble in common solvents such as chloroform, methanol, ethanol, dimethyl formamide, dimethyl sulfoxide, acetonitrile, dioxane, acetone, 2-propanol, and toluene—a necessary condition for observing solvatochromism. The molar conductivity values, equal to 0.0 S mol-1 cm2 in these solvents, point to a typical non-electrolyte behavior for this complex. Spectroscopic measurements were used to confirm the square-planar geometry of the species in solution and to determine the coordination properties of the donor atoms and their bonding abilities (CFM/AOM parameters), as well as trichromaticity coordinate calculations. The results obtained show that the interactions of the metal with the donors depend on the polarity of the solvent.