Syntheses, Crystal Structures And Characterization Of The Complexes Of Copper(II) With 3-Methyl-4-Aryl-5-(2-Pyridyl)-1,2,4-Triazole

1,2,4-Triazoles have gained considerable attention in recent years. Because they can form complexes with transition-metal ions, and some of them exhibit spin crossover behaviour, which can be used potentially to molecular electronic devices. In order to synthesize and research the novel complexes of transition-metal ions with 1,2,4-triazoles, the complexes of copper(II) ion with 3-methyl-4-aryl-5-(2-pyridyl)-1,2,4-triazoles have been synthesized and characterized, and their crystal structures were determined by X-ray analysis. The thesis is composed of the following three sections:Part I. Two novel 1,2,4-triazoles of 3-methyl-4-phenyl-5-(2-pyridyl)-1,2,4-triazole(L1) and 3-methyl-4-p-methoxylphenyl-5-(2-pyridyl)-1,2,4-triazole(L2) were synthesized by several -step reactions fromα-picoline, and were confirmed by IR,1H-NMR and MS spectra.Part II. The complexes of [CuL₂²Cl₂]·3 13 H₂O and [CuL₂² Sal₂]·2CH₃OH have been prepared, and the crystal structures of L2·2H₂O,[CuL₂²Cl₂]·3 13 H₂O and [CuL₂² Sal₂]·2CH₃OH were determined by X-ray analysis. The crystal structure of L2·2H₂O shows that the three aryl rings of 1,2,4-triazole ring,pyridine ring and benzene ring in L2 do not share a common plane. The central Cu(II) ions of [CuL₂²Cl₂]·3 13 H₂O and [CuL₂² Sal₂]·2CH₃OH have centrosymmetric and distorted trtragonal-octahedral geometries with CuN2N2′Cl2 and CuN2N2′O2, respectively.Part III. The ESR spectra at low temperature,electronic absorption spectra in thin solution and thermal gravimetric analysis of [CuL₂²Cl₂]·3 13 H₂O and [CuL₂² Sal₂]·2CH₃OH were measured. As the central Cu(II) ions of the two complexes are anisotropic, they give three g-values ESR spectra. The g-values of [CuL₂²Cl₂]·3 13 H₂O are g1=2.2182 with A‖=176G,g2=2.0629,g3=2.0139. And those of [CuL₂² Sal₂]·2CH₃OH are g1=2.1839 with A‖=172G ,g2=2.0632,g3=2.0139. Thermal gravimetric analysis shows that as temperature rises, the two complexes first lose their crystal water and crystal methanol, respectively, and then decompose gradually at higher temperature.