Synthesis, Characterization And Property Study Of Transition Metal Complexes Of Pyrazolone Hydrazine And Hydrazone

The design, synthesis and relative properties of functional coordination compounds are focus in the field of coordination chemistry. A more rational approach to predetermined molecular architectures uses polyfunctional ligands, with well designed and judiciously positioned donor pockets arranged so that binuclear or polynuclear complexes can be observed. Therefore the multidentate ligand is a critical factor in this operation. 4-acyl-pyrazolone derivatives are broadly used in many fields in the society, especially in biological, clinical and analytical applications. On the other hand, compounds containing salicylidene hydrazone or hydrazine and its complexes also possess biological activity and its phenoxy is capable of chelate and bridge properties. So we expect the formation of polyfunctional ligands and polynuclear metal complexes using the combination of 4-acyl pyrazolones and salicylidene hydrazone or hydrazine. In order to further enrich and extend the studies on the functional complexes, such as predetermination of molecular architectures and the properties of the binuclear or multinuclear complexes, six novel acylpyrazolone derivatives and their transition metal complexes have been synthesized and characterized. The formation and probability of binuclear or polynuclear complexes have been investigated by X-ray diffraction analyses of the complexes. Meanwhile, it has been discussed the probability and rule of the formation of dimensional structure mixed-ligand complexes with pyridine as the second ligand. The paper consists of five parts.In the first part, a novel acylpyrazolone derivations N-(1,3-diphenyl-4-benzylacetyl- pyrazolone-5)-salicylidene hydrazone (DPPaP-SAH) and its transition metal complexes have been synthesized and characterized by elemental analyses, TG-DTA, IR spectra, molar conductance and single crystal X-ray diffractions. Furthermore, thermal and electrochemical properties of the ligand and its transition metal complexes have been studied. It has been estimated that a structure conformation of the ligand DPPaP-SAH has been occurred during the formation of the complexes. The X-ray diffraction analysis of the complex shows that the structure of [Zn4(DPPAP-SAH)4] consists of four pentacoordinated Zn(Ⅱ) ions linked to three tetradentate ligands forming a macromolecular cyclic system. The coordination geometry around the five coordinate Zn(Ⅱ) ions is slightly distorted trigonal bipyramid. The deprotonated oxygens O2 serve as bifurcate bridges between the Zn(Ⅱ) ions forming tetra-μ-phenolatotetrazinc (Ⅱ) centers. While the X-ray diffraction analysis of dinuclear copper(Ⅱ) complex [Cu2(DPPaP-SAH)2]·0.5H2O shows that two Cu(Ⅱ) centers are bonded with two tetradentated ligands. The geometry around two Cu(Ⅱ) is slightly distorted square planar and there is no μ-phenoxo bridge in the complex. Several factors that can make unpredictable transition metal complexes assisted self-assembly have been discussed. In the second part, N-(1,3-diphenyl-4-benzal-pyrazolone-5)-salicylidene hydrazone (DPBP-SAH) and its transition metal complexes have been synthesized and characterized by elemental analyses, TG-DTA, IR spectra and single crystal X-ray diffractions. It has been observed that the different coordination modes and steric properties of the ligand, the chemical nature of the metal ions with their own coordination performances and the presence of other additional donor molecule are all the important factors that can induce the various metal complexes.In the third part, N-(1,3-diphenyl-4-acetyl-pyrazolone-5)-salicylidene hydrazone (DPAP-SAH) and its transition metal complexes have been synthesized and characterized by elemental analyses, TG-DTA and IR spectra. It has been suggested that the transition metal complexes of this kind of ligand are all binuclear or polynuclear, which confirm the hypothesis in the second part that a lower steric hindrance group introduced in the 4 position of the pyrazolone seem to induce the formation of the dinuclear or polynuclear complexes.In the fo...