Synthesis, Spectroscopic and Magnetic Studies of Cobalt(II), Nickel(II) and Copper(II) Complexes with 3′- and 5′-Methoxysalicylaldimine-3-Ethylene-1H-Indole. X-Ray Structure of BIS(1H-Indole-3-Ethylene-5′-Methoxysalicylaldimine)Copper(II)

Abstract

Two bidentate ligands and their cobalt(II), nickel(II) and copper(II) complexes are reported; these ligands were prepared by 1:1 Schiff base condensation of 3-(2-aminoethyl)indole (tryptamine, TPA) with salicylaldehyde derivatives. The structures of the compounds were assigned on the basis of IR, electronic, mass and ^tH NMR data. Bis(1H-indole-3-ethylene-5′-methoxysalicyIaldimine)copper(II), (C₃₆H3₄N₄O₄Cu), crystallized in monoclinic space group P2₁/c and was subjected to a single-crystal X-ray structure analysis. The structure was solved by direct and Fourier methods, refined by full-matrix least-squares, and converged to a R value of 0.038 for 1358 observed reflections. The coordination of the copper(II) complex is trans-planar (CuO₂N₂) with Cu-O and Cu-N bond lengths of 1.88(1) Å and 2.01(1) Å, respectively. The magnetic susceptibilities of the two copper complexes show normal magnetic behaviour in the range 79–279 K. The coordination of the two nickel complexes is trans-planar (NiO₂N₂) and both complexes are diamagnetic at room temperature (297 K). The spectroscopic and magnetic data for bis(lH-indole-3-ethylene-5′-methoxy-salicylaIdimine)cobalt(II) is consistent with an octahedral environment around the metal.

Key Words:

• Schiff base
• indole
• complexes
• X-ray structure
• first row