Complexes of copper(II) and nickel(II) with the new ligand N-[2-(3-ethyl-indole)]pyridoxaldimine. X-ray crystal structure of bis{N-[2-(3-ethyl-indole)]pyridoxaldiminate}nickel(II)

Abstract

The monoanionic bidentate ligand N-[2-(3-ethyl-indole)]pyridoxaldimine prepared by 1:1 Schiff-base condensation of 3-(2-amino-ethyl)indole (tryptamine, TPA) with [3-hydroxy-5-(hydroxy-methyl)-2-methyl-4-pyridinecarboxaldehyde] (pyridoxal, pyrdox) and three different copper complexes are reported. The nickel(II) compound with the same ligand is also studied. All complexes were characterized by IR, UVvis and 1H NMR spectra, magnetic measurements and thermoanalytical data. A single-crystal of the nickel complex was subjected to X-ray diffraction analysis. The coordination of the nickel(II) complex is trans planar (NiN 2O 2) with NiO and NiN bond lengths of 1.841(l) and 1.926(2) Å, respectively. The spectroscopic data for the copper(II) complexes suggest the same chromophore group (CuN 2O 2) with a trans configuration in the solid phase for all. Finally, the dehydration reaction Cu(pyrdoxTPA) 2· yH 2O(s) → Cu(pyrdoxTPA) 2(s) + yH 2O(g) for the two copper complexes is studied.