Design, Synthesis, Structure And Properties Of Acylamino Schiff Base And Asymmetrical Double Schiff Base Complexes

The molecular-based magnetic materials have shown spectacular advances over the past two decades, in which the study of heterometallic binuclear complexes has played an important and leading role. A number of heterometallic binuclear complexes have been synthesized and their magnetic properties have been investingated. It is well known that the magnetic interactions between two nonequivalent paramagnetic centers may lead to situations that cannot be encountered in species containing only one kind of center. A successful strategy in obtaining the desired spin topology is the "complex as ligand" approach. These anionic precursors are particularly suitable for designing heterometallic complexes and have played an important role in the development of molecular magnetism. Acylamino-Schiff bases containing phenol-oxygen groups and amido group are good versatile organic ligands, which can chelate as well as bridge metal ions to construct discrete and extended structures, further forming 1D, 2D or 3D structure polymers with infinitely extended chain structure. They should play an important for the study of magnetic property. In view of reasons above and from the standpoint of molecular design, we have designed and synthesized asymmetrical mononuclear,heterotrinuclear complexes and heterometal polymers of acylamino-Schiff bases containing phenol-oxygen groups and mononuclear ,heterotrinuclear complexes of asymmetrical double Schiff base. These compounds were characterized by single-crystal X-ray analysis and executed properties study. The main contents are described as following: (1) According to the principle of ester aminolysis, we have prepared the compound [N-(2-Hydroxybenzamido)-N'-(2-amino)ethane] by ethyl salicylate and ethylene- diamine mixed and refluxed at 110°C. Asymmetrical acylamino-Schiff base ligand H4L containing phenol-oxygen groups was also obtained by 3-Carboxylsalicylidene and N-(2-Hydroxybenzamido)-N'-(2-amino)ethane refluxed in ethanol. Further, we synthesized copper mononuclear complex(K₂CuL)and nickel mononuclear complex(K₂NiL) by the ligand H₄L and Copper(II) acetate monohydrate (or nickel(II) acetate tetrahydrate) refluxed in ethanol. These compounds were characterized and investingated by IR Spectra, elemental analyses and thermogravimetric analyses et al. A series of heterometal complexes have been designed and synthesized by copper mononuclear complex(K₂CuL)and d-transition metal ions M²⁺ self-assembly in methanol at room temperature and their UV-Vis spectra, IR spectra, thermal properties and magnetic Properties et al. have been studied. Their crystal structures have been determined by X-ray analysis. These heterometal complexes are 1D infinite chain-structure polymers, there are unnumber cyclic tetranuclear structure in every chain, the tetranuclear cyclic have two different sorts of structures, are arrayed alternately and constructed these long molecules chain. The variable magnetic properties of these polymers have been determined in the temperature range 5³00K, which indicate that the interaction between the metal ions is antiferromagnetical. The magnetic susceptibility was analyzed by eq derived from the approximate modal[1²] previously reported and obtained satisfactory result. When substituting copper mononuclear complex (K₂NiL) for nickel mononuclear complex (K₂CuL) above the reaction, a series of heterometal polymers are also obtained. Because square planar nickel complexes are of diamagnetism, their properties have been investingated except for magnetic properties, Their crystal structures have been determined by X-ray analysis, which they have approximate structure with the former. (2)Asymmetrical acylamino-Schiff base ligand H3CSe (figure(b)) containing phenol-oxygen groups was also obtained by 5-chlorosalicylaldehyde and N-(2-Hydroxybenzamido)-N'-(2-amino)ethane refluxed in ethanol. Further, we synthesized copper mononuclear complex(KCuCSe)by the ligand H₃CSe and Copper(II) acetate monohydrate refluxed in ethanol. Two sorts of cis-heterometal triunclear complex...