Synthesis and characterization of Mn(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes of heptadentate asymmetrical tripodal Schiff base

Bis(2-aminoethyl)(3-aminopropyl)amine, 2-pyridinecarboxaldehyde and a number of metal ions were used to prepare metal complexes of tripodal Schiff base ligand (L-322). The resulting complexes, [M(L-322)](ClO4)(2) [M = Mn(II), Ni(II), Cu(II), Zn(II) and Cd(II)]; L-322 = N[CH2CH2CH2N=CH(C5H4N)][CH2CH2N=CH (C5R4N)](2), were characterized by microanalysis and IR spectra in all cases and by H-1 NMR Spectra in the case of Zn(II) and Cd(II) complexes. In the H-1 NMR spectrum of the cadmium complex the signals of imine protons having two clear satellite peaks ((3)J = 44.41-47.64 Hz) with rarely observed intensities in the ratio 1 : 6 : 1 due to coupling with neighbouring Cd-111/113. The ab initio studies on [Zn(L-322)](2+) and [Cd(L-322)](2+) complexes were also reported. The results show that the most bonding interaction between the metal ion and the bridging tertiary nitrogen atom of ligand occurs in the Cd(II) complex.