Synthesis of Mononuclear Metal Complexes with Some Tetradentate Schiff Base Ligands

Abstract

Abstract A series of Cu(II), Ni(II) and Co(II) complexes with N,N′-bis-[5-X-salicylidene]-2,2′-diaminodibenzyl [H2-XSalDDB (X[dbnd]H, CH3, Br)] have been prepared. The metal complexes were characterized on the basis of elemental analyses, electrical conductance, magnetic susceptibility, spectral and thermal studies. All of the complexes are non-electrolytes of 1:1 (M:L) stoichiometry. The room temperature magnetic susceptibility and electronic spectral data support a pseudo-tetrahedral geometry for the complexes. The IR spectra show that the Schiff bases function as tetradentate ligands coordinating through the ON-NO donor system. Substitution on the phenyl ring of the complexes produces a shift in the azomethine v(C[dbnd]N) stretching vibrational frequency which is related to Hammett's substituent parameter [sgrave]. The 1H NMR data reveal that all Schiff bases exist in the enol-iminic form. Various ESR parameters for the copper complexes have been calculated. The thermal curves of the chelates are single-stepped and indicate the absence of water molecules.