.3,5 - Pyrazole Dicarboxylic Acid Transition Metal Complexes, Synthesis, Structure And Characterization

With the development of the syntheses and researches in functional complexes, the researches in molecular materials with magnetic properties have developed rapidly. Search for good ligands is main direction to synthesize molecular magnets. In this thesis, four transition metal coordination polymers of 3,5-pyrazoledicarboxylic acid and alkali organic ligand (e.g pyridine (Py) or Ethylenediamine (en)) were prepared from water or methanol. The three transition metal coordination compounds of with N,N'-bis(salicylidene)-2,6-pyridinediamine(H₂L) were prepared from methanol.The basic-concepts, species, methods of syntheses and their applications are briefly summarized; H₃Dcp and symmetric bis-Schiff base are reviewed concisely.Four new transition metal coordination polymers [Ni₄(HDcp)₄(Py)₁₂]·2(Py)·5CH₃OH·3H₂O(1), [Cu(en)₂](HDcp)·CH₃OH·H₂O(2), [Ni(en)₃]₃(HDcp)₃·5H₂O(3) and [Co(en)₂(HDcp)]·5H₂O(4) with Py or en as control-ligand were synthesized and characterized by elemental analysis, IR spectra, thermogravimetry analysis and X-ray crystallography. The results show the coordination polymer 1 revealed a unique "open-box" molecule; Each Ni is six-coordinate distorted octahedral structure. For the coordination geometry of Ni, one HDcp^2- bonds the metal through its carboxylate oxygen O and its adjacent pyrazole nitrogen N, and another HDcp^2- bonds the metal through its carboxylate oxygen O, and pyridine molecule bonds the metal through its N. H₃Dcp do not bond with metal in the complexes 2 and 3, and it is in structure as anion HDcp^2-. Ligand en bonds the metal through its N. Cu²⁺ is four-coordinate in complex 2, Ni²⁺ is six-coordinate in complex 3. H₃Dcp and en bonds with metal in the complex 4, the HDcp^2- bonds the metal through its carboxylate oxygen O and its adjacent pyrazole nitrogen N, and the en bonds the metal through its N.A series of homotetranucleus complexes (H₂Dcp)₅(H₃Dcp)_0.7ErCo·10H₂O, (H₂Dcp)₅(H₃Dcp)₄ GdCo·20H₂O, (H₂Dcp)₂(HDcp)FeMn·6H₂O have been synthesized by the assembly reaction of rare earth nitrate and transition metal nitrate, and control pH with nitric acid. Complexes [Co(H₂Dcp)₂(H₂O)₂]·H₂O and (H₂Dcp)₂(HDcp) FeMn·6H₂O were obtained.The three transition metal complexes of (Cu, Ni and Co) with N,N'-bis(salicylidene)-2,6-pyridinediamine(H₂L) were prepared from methanol. The complexes have been characterized by elemental analysis and thermogravimetry analysis. Compositions of these complexes were confirmed to be CuL·5H₂O, NiL·5H₂O, CoL·2H₂O. IR spectra and UV spectra of the complexes are described. The results show two phenolic oxygen and two imino nitrogen atoms of H₂L coordinate to M(Ⅱ) ions. The cyclic voltametric behavior of the complexes is also reported.