Synthesis And Structure Chemistry Of The Polyoxotungstates

Polyoxometalates have always attracted many interests because of not only its structural variety and diversity properties but also potential application in analytic science, biomedicine and catalysis. On the basis of molecular design and assembly, we try to introduce transition metals and organic molecular into the inorganic building block of polyoxometalates, and obtained classical and vacant polyoxotungstates with ordinary tungatate and trivacant precursor as starting material.In this thesis, we obtained nine polyoxotungstates on the basis of consultant of the literature home and abroad, and studied the relationship of structure and spectroscopy further, we also employed Gaussian 03 program to calculate some of the polyanions, and lay foundation for its application, the main work is as follows:1. Nine novel polyoxotungstates were obtained through thermal technique, X-Ray single crystal diffractometor technology was carried to determine those structure further. The nine compounds can be clarified to three types according to the polyanion:(1) Compounds 1,2 and 3 are classical Keggin structure and mono-substituted Keggin structure (2) Compounds 4-8 are the dipolymer of trivacant Keggin structure, their polyanions are [Mn2(H2O)6(WO2)2(SbW9O33)2]10- (Krebs type), [{KNa2(H2O)6][Cu(H2O)]3(SbW9O33)2]8- (Herve type), [Cd4(H2O)2(SiW9O34)2]12-(Weakley type), [SbW18O60]9- (Dawson-liketype) respectively (3) Compound 9 exhibits a novel polyanion in which a distorted Anderson structure with Sb as heteroatom bind to a four-membered copper cluster, and this type of polyanion have not reported before. Compound 1、2、 7、 8 are isolated structure, compound 3 and 5 are 1D infinite chain with sharing terminal oxygen and Na-H2O cluster separately; compound 6 and 9 are 2D layer structure linked by Na-H2O cluster and the complex of copper respectively; compound 4 is a 3D framework linked by five-membered Na-H2O cluster.2. We also carried out IR,2D-IR correlation spectra, UV-DRS, TGA, X-ray power diffraction and X-ray photoelectron spectroscopy to characterize some compounds. The IR spectra of nine compounds display obvious W-O characteristic vibration absorption; the thermal-perturbation 2D-IR correlation spectra show the skeleton response of polyanions, and magnetic-perturbation 2D-IR correlation spectra indicate the response of group which magnetic metal ion attached; the LMCT bands of O→W are also found in UV-DRS spectra; TGA indicate that the skeleton of polyanion is stable below 300℃；the XPS demonstrate that the Co is +2 in compound 1, Fe is+2 and +3 in compound 2, Cu is +2 in compound 5; compound 9 display a paramagnetic properties and has potential appliacation in magnetic material.3. In this thesis, we also employed Gaussian 03w program to calculate the polyanion [CoW12O40]6-, [FeW12O40]5- of compounds 1 and 2 and studied the bonding nature and reactive center, we obtained the single point energy, frontier orbital energy and Mulliken charge of polyanion system, the relationship of energy and structure was also discussed.