| The main work is comprised three chapters in this thesis:1: A novel hybrid compound, [HDMA]6[Cu(DMF)4(GeWi2O4o)2]-2DMF, has been synthesized from H4GeW12O40nH2O, CuCl2 and N, N-dimethylformamide (DMF) and characterized by elemental analyses, UV and IR spectra. X-ray structure analysis shows that it belongs to monoclinic system, space group P21/c, a=13.586(3) A, b=20.015(4) A, c=20.524(4) , =104.88(3), V=5394.1(19) 3, Dc= 4.070g/cm3 , Z=2. The molecular structure of the [{Cu(DMF)4}(GeW 12040)2]6- anion consists of two anionic Keggin GeW12O404- units which are each coordinated through a bridging O atoms, O(1), to the central Cu atom of the Cu (DMF) 42+ cation. The TG analysis of the title compound shows two steps for loss of weight, at 526.2 C represents the decomposition of heteropolyanion GeW12O404-. The data indicate the stability of the GeW12O404- anion is stronger in the title compound than that in the acid.2: A new compound [Yb(DMSO)7][HSiMo12O40] has been synthesized from H4SiMo12O40nH2O, YbCl3 and DMSO and characterized by elemental analysis, IR spectra and single crystal X-ray diffraction. X-ray structure analysis shows that it belongs to monoclinic system, space group P21/c, with M=6616.2090 gmol-1, a=13.586(3) A, b=20.015(4) A, c=20.524(4) A, /M04.88(3), V=5394.1 ( 19) 3, Dc= 4.070g/cm3 , Z=2, F(000)=5810. The crystal structure indicate [Yb(DMSO)7]3+ as a distorted pentagonal bipyramid cation combined to the [SiMo12O40]4- anion by static electric force.3: This chapter is the main work of the paper. A new series of complexes constructed from coordinated Ln 3+ unit and heteropolyanion [SiMo12O40]4- have been synthesized and we give this serial of compounds necessary determinations such as elemental analysis, IR spectra and single crystal X-ray diffraction. X-ray structure analysis shows that they all belong to monoclinic system, space group P2i/c, withAll crystal structures indicate that the coordinated ions combine to the [SiMo12O4o]4- anion by static electric force. In order to obtain some useful system about the affect in structure and characterizations of lanthanide contracts, ESR, TG-DTA and CV are employed in these systematic studies of their properties.(1) The IR spectra of the series complexes are similar. There are four characteristic asymmetric vibration peaks for herteropolyanions with Keggin structure. Comparing the IR spectra of compounds with those of -H4SiMo 12040, all the vibration peaks have red-shifted and blue-shifted to a different extent. The results indicate that the polyanions of these compounds still maintain basic Keggin structures, but are distorted due to the influence of coordination effect.(2) An important feature of the lanthanide elements is the occurrence of the lanthanide contraction, which is well confirmed by the following fact: firstly, thecoordination numbers are decreased from 8 to 7 with the increasing atomic number; secondly, as we expected for a decrease of Ln-O average bond distances (A) of these complexes, according to the increase in the ionic radii (A); finally, the considerable change in size of the Ln3+ ion means that homologous compounds of Lanthanides with appreciably different radii may differ in structure.(3) All the ESR spectra of the seven compounds show a shaped signal, which is the typical signal of molybdenum(V) at 110 K and is assigned to the intervalence charge transfer IVCT band of SiMo12O404-. In Gd3+ compound, some other Gd3+ signals could be observed due to the special character of Gd3+,(4) Through determinations of CV, their electrochemical properties are studied. We find that each of them has nice electrochemical properties and reversible redox properties, and the polyanion is the reaction active center.(5) The results of thermal properties of this series compounds indicate the stability of the SiMo12O404- anion is stronger in the title compound than that in the acid and represent a particular tendency. |
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