| Schiff base and its transition metal complexes have significant antiviral and antibacterial activities. In particular unsymmetrical Schiff base complexes have attracted considerable interest within recent years because of their specific structures and properties. In addition, molecular magnetism and heteropolymetallic complexes are active fields of research encompassing chemistry, physics, biology and material science. The magnetism of heteropolymetallic complexes containing multiatomic bridges has received considerable attention, and much work has been devoted to studying the magnetism of polynuclear Schiff base complexes containing-phenolic oxygens as bridges. But a successful strategy leading to unique heteropolymetallic complexes or one-, two-, and three-dimensional (1D, 2D, 3D) systems is the way of metal cations linking to stable coordination compounds containing potential bridging blocks, i.e. the "complex as ligand" approach.In view of reasons above and from the standpoint of molecular design, we attempt to design and synthesize symmetrical and unsymmetrical mononuclear, binuclear and heterotrinuclear double Schiff base complexes through complex as ligand. These compounds were characterized by single-crystal X-ray analysis and executed properties study. The main contents are described as following:(1) The homobinuclear complex Cu2(fsa)2en(H2O) 5H2O, where (fsa)2en is the binucleating ligand derived from the schiff baseN,N'-bis(3-carboxylsalidene)enediamine, was obtained sellassembly. Its crystal structure has been determined by X-ray analysis. The crystal is orthohombic system, space group Pbca, a = 16.086(3)A, b = 13.363(3)A, c = 20.650(4)A, B = 90.0° , Z = 8, R1 = 0.0483, wR2=0.0968 The structure is made of binuclear units, in which two copper atoms are bridged by two phenolic oxygen atoms. The " inside "copper atomCu2 is in a planar coordination site of [N2O2], and it deviates from the mean plane by 0.144A. The "outside" copper atom Cul is in a distorted pyramid site of [O5], but it is pulled out of the equatorial plane by 0.238 A.Two symmetrical double Schiff bsase heterobinuclear complexes : CuVOTSMeOH and NiFe(TS)Cl 2.5H2O, where TS = N,N'-bis(3-carboxylsalidene)trimethylenediamine, were synthesized and characterized by elemental analysis, molar conductivity, thermal analysis, IR and UV-visible spectra. The electrochemical properties of two compounds were examined by cyclic voltammetry in DMSO. The results show that the coordination of the second metal ion has increased the electrochemical stability of the inner ion. The temperature dependence of the magnetic susceptibility of Cu(II)-VO(II) over the range 4-300K gave the exchange integral of J=-1.6312cm-1,which indicates that in the heterobinuclear complex the interaction between the internal Cu2+ ion and the outer VO2+ ion is weak anti ferromagnetic.(2) Using metal ions as template, we have obtained two kinds of new unsymmetrical double Schiff base Cu(II) mononuclear complexes: HCuLe and HCuLt, where H3Le=N-3-carboxylsalicylidene-N'-salicylaldehyde-1,2-diaminoethane and H3Lt= N-3-carboxylsalicylidene-N'-salicylaldehyde-l, 3- diaminopropyl. They have been characterized by means of elemental analysis, IR and UV-visible spectra, thermogravity analysis. The crystal structure of HCuLe. has been determined. The crystal is monolinic system, space group Cc, a = 25.326(5)A, b = 8.8861(18)A, c = 13.738(3)A, B = 96.95(3)° , Z = 4, R1 = 0.0520. The molecular structure of thiscomplex is dimeric and has extended phenolic oxygen-bridged structure consisting of one square-pyramidal copper(II) and one square-planar copper(II) ions.(3) Using mononuclear complex HCuLe as building blocks,' we have synthesized four heterotrinuclear complexes Cu(II)-M(II)-Cu(II), where M= Co2+, Ni2+, Zn2+, Mg2+.They have been characterized by means of elemental analysis, IR, electronic spectra. The crystal structures of these heterotrinucler complexes were determined b...
|
PDF Full Text Request