亚砷钨杂多化合物的合成结构及性质研究

【作者】 刘斌；

【导师】 薛岗林；

【作者基本信息】 西北大学 ， 物理化学， 2003， 硕士

【摘要】 杂多化合物由于其组成和结构多样性，及其在催化、材料科学，环境保护及医学等领域所具有的潜在应用前景而引起人们的广泛兴趣，超大杂多化合物的设计合成及其结构性质研究一直是该领域具有挑战性的课题之一，引起许多领域科学家的关注。 本课题致力于亚砷钨酸盐超大杂多化合物的合成，结构及性质研究。由于As（Ⅲ）具有一对孤对电子，聚合只能形成不饱和的三缺位Keggin结构AsW₉O₃₃^9-。AsW₉O₃₃^9-单元可被过渡金属离子，稀土离子，有机锡等无机和有机集团桥连形成结构新颖的大聚离子。论文中合成了八类夹层型和环聚离子及其衍生物。其分子式如下： 结构研究表明，（Ⅰ）（Ⅱ）（Ⅲ）（Ⅳ）类化合物是由两个{α-B-AsW₉}单元形成的夹层型阴离子，夹层间存在1～3个M（L）²⁺或者VO³⁺，M是过渡金属离子，L是H₂O或者有机配体。环聚离子（Ⅴ）具有全新的结构，是由三个{WO（H₂O）}桥连三个我们新发现的{AsW₈O₃₁}单元构成，环聚离子具有D_3h对称性。环内是一大的空腔，被两个Na⁺所占据。聚阴离子（Ⅵ）的结构表明，大环配体[As₄W₄₀O₁₄₀]^28-内四个S2位分别被两个Na⁺和两个Ni²⁺所占据，第三个Ni²⁺与大环外的端基O_d，这是首例关于环外端基O_d配位的阴离子结构报道。聚阴离子（Ⅶ）的结构表明，大环配体[As4讯00140]zs’内的中心sl位被稀土离子占据，sl位提供四个od向稀土离子配位，两个s2位分别被两个Ni2+所占据，另外两个s2位附近存在两个氢键作用的NH4+。聚阴离子（姗）的结构表明，大环配体[A s4W40o;40〕28-内四个s2位分别被Ni2+，vo3+和两个Na+所占据。首次解析了Nag[C ew100361·34H20的晶体结构，并与其它稀土类夹心化合物作了比较。解析了耘困iw6O24残」·12珑0的晶体结构，补充了它的结构数据。 化合物均作了红外光谱，紫外一可见光谱和元素分析，对化合物（I）（W）（V）（珊）作了热失重分析，对化合物（I）（恤）作了磁性质研究，另外还对化合物（V）作了‘“3w NMR测试，对离子间的部分氢键作用作了讨论。更多还原

【Abstract】 Heterpolyoxometalates have received much attention due to their fascinating variety of structure and chemical composition, and potential applications in catalysis, materials science, environmental protection and medicine. The synthesis design, structure properties of novel large polyoxometalates and derivatives of known polyoxometalates are interesting and remain a challenge.This thesis is devoted to the topic of the synthesis and structural characterization of polytungstate ions containing arsenic (IE). The lone pair of electrons on the As (HI) inhibits formation of the classic Keggin structure. This open structure may be used to construct novel large species by linking with inorganic or organic groups, such as transition metal cations, lanthanide cations, PhSn3+ and so on. Altogether eight new type heterpolyoxometalates including sandwich type heteropolytungstate and big cyclic polyanion have been synthesized and characterized structurally. Their formulas are as follows:The results of the crystal structure analysis show that among the compounds (I)(II) (III) (IV), the structure of anion reveals a arrangement of two (a-B-AsW9)moieties enclosing one, two or three M(L)2+. The compound (V) consists of threenew (AsW8O31) subunits related through a C3 axis and joined up by three extra(WO(H2O))group. Each (WO(H2O)) joints two AsW8O31 subunits by sharing two cis oxygen atoms with each other, the polyanion [{WO(H2O)}3(AsW8O31)3]21- has approximately D3h symmetry. The compound (VI) shows that the four S2 sites of the big cyclic ligand [As4W40O140]28- are occupied by two Na+ and two Ni2+ respectively, the third Ni2+ locates outside the cyclic [As4W4oO140]28- and connects with one Od, its coordination number is six. the compounds (VII) show that show that the central site S1and two opposite S2 sites of the big cyclic ligand [As4W40O140]28- are occupied by one Ln3+ and two Ni2+ respectively, five molecular waters coordinate to Ln3+. The compounds (VIII) show that two opposite S2 sites of the big cyclic ligand [As4W40O140]28- are disorderly occupied by one VO3+ and one Ni(H2O)2+, and other two are occupied by two Na+ connected by a bridging water.Most of the compounds have been investigated with IR, UV-Vis spectra and element analysis. TG-DTG have also been recorded for the compounds (I) (IV) (V) and (VI). The magnetic properties of the compounds (I) and (VIII) have been studied. The compound (V) was also characterized by 183 W NMR. Finally, some of hydrogen-bond interaction are discussed.更多还原