Abu-Hussen Azza A A, Linert Wolfgang
Chemistry Department, Ain Shams University, Women Faculty for Arts, Science and Education, Heliopolice, Cairo, Egypt.
Spectrochim Acta A Mol Biomol Spectrosc. 2009 Sep 15;74(1):214-23. doi: 10.1016/j.saa.2009.06.023. Epub 2009 Jun 16.
Complexes of two series of Schiff base ligands, H(2)L(a) and H(2)L(b) derived from the reaction of 2,6-diacetyl pyridine with semicarbazide, H(2)L(a) and thiosemicarbazide, H(2)L(b), with the metal ions, Co(II), Ni(II), Cu(II), VO(IV) and UO(2)(VI) have been prepared. The ligands are characterized by elemental analysis, IR, UV-vis and (1)H NMR. The structures of the complexes are investigated with the IR, UV-vis, X-band ESR spectra, (1)H NMR and thermal gravimetric analysis as well as conductivity and magnetic moment measurements. The IR-spectra reveal the presence of variable modes of chelation for the investigated ligands. A variety of binuclear or mononuclear complexes were obtained with the two ligands in tri-, tetra or pentadentate forms. The bonding sites are the pyridine nitrogen, two azomethine nitrogen atoms and ketonic oxygen in case of H(2)L(a) or sulphur atoms in case of H(2)L(b). The Coats-Redfern equation has been used to calculate the kinetic and thermodynamic parameters for the different thermal decomposition steps of some complexes. Cyclic voltammograms of Co(II) and Ni(II) show quasi-reversible peaks. The redox properties and the nature of the electro-active species of the complexes have been characterized.
已经制备了由2,6 - 二乙酰吡啶与氨基脲反应衍生的H₂L(a)和与硫代氨基脲反应衍生的H₂L(b)这两个系列席夫碱配体与金属离子Co(II)、Ni(II)、Cu(II)、VO(IV)和UO₂(VI)形成的配合物。通过元素分析、红外光谱、紫外可见光谱和¹H核磁共振对配体进行了表征。利用红外光谱、紫外可见光谱、X波段电子顺磁共振光谱、¹H核磁共振以及热重分析以及电导率和磁矩测量对配合物的结构进行了研究。红外光谱揭示了所研究配体存在多种螯合模式。用这两种配体以三齿、四齿或五齿形式获得了多种双核或单核配合物。对于H₂L(a)，键合位点是吡啶氮、两个甲亚胺氮原子和酮氧；对于H₂L(b)，键合位点是硫原子。科茨 - 雷德芬方程已用于计算一些配合物不同热分解步骤的动力学和热力学参数。Co(II)和Ni(II)的循环伏安图显示出准可逆峰。对配合物的氧化还原性质和电活性物种的性质进行了表征。
