【作者】 李云高；

【导师】 许林；

【作者基本信息】 东北师范大学 ， 无机化学， 2010， 硕士

【摘要】 本论文采用缺位的多金属氧酸盐作为前驱体,在常温水溶液中,通过对反应过程中溶液的pH值、温度、配体、抗衡阳离子和配料比的摸索,成功地合成了5个新型的稀土离子修饰的多金属氧酸盐。通过单晶X-射线衍射分析了化合物的结构,利用元素分析、红外、热重、紫外对其进行了表征,并对化合物在2-300K范围内的磁学性质进行了研究。1.以双缺位Keggin型多酸阴离子[γ-GeW₁₀O₃₆]^8-作为前驱体,成功地合成了两例新型的稀土取代的多金属氧酸盐: Na₁₂[Dy₄(α-GeW₁₀O₃₈)₂（H₂O）₆]·36H₂O （1） Na₁₂[Er₄(α-GeW₁₀O₃₈)₂（H₂O）₆]·29H₂O （2）化合物1和2属于同构的无机化合物。在该类化合物中,四个稀土离子位于两个多酸阴离子[α（1,4）-GeW₁₀O₃₈]^12-之间。同时,每个稀土位于缺位与五个氧原子相连,在这五个氧原子中,有四个来自于WO₆八面体,另外一个来自于GeO₄四面体。这类化合物是首例四个稀土离子位于两个双缺位的锗钨酸阴离子之间,而形成的二聚体稀土多金属氧酸盐。2.以三缺位Keggin型多酸阴离子[α-GeW₉O₃₄]^10-作为起始原料,通过调节溶液合适的pH值,成功地得到了一例1:2夹心型结构的多金属氧酸盐: （C₄H₉NO）(C₄H₁₀NO)₁₃[(GeW₁₁O₃₉)₂Nd]·9H₂O （3）3.以单缺位Keggin型多酸阴离子[α-BW₁₁O₃₉]^9–作为基本建筑块,在缓冲溶液中与稀土离子的配位组装,成功地得到了两例经典夹心结构的稀土多金属氧酸盐: Na₂（C₃H₅N₂）₁₂H[(BW₁₁O₃₉)₂Pr]·7H₂O （4） K₂Na₆[N（CH₃）₄]₃H₄[(BW₁₁O₃₉)₂Dy]·23H₂O （5）在该类化合物中,两个单缺位Keggin型多酸阴离子[α-BW₁₁O₃₉]^9–分别作为四齿配体,利用缺位的四个端氧与镨离子配位,形成夹心型的结构。同时,在化合物4中,两个相邻的夹心型阴离子[(BW₁₁O₃₉)₂Pr]^15-,通过[Na₂（C₃H₅N₂）₂]⁴⁺单位的连接在ab平面形成二维层状结构。更多还原

【Abstract】 Based on vacant POMs as precursor, we explored the process of reaction condition, which includes pH in aqueous solution, temperature, ligand, counterion and ratio of mixture, and successfully synthesized five new lanthanide polyoxometalates （LnPOMs） at room temperature in aqueous solution. We analyzed the structures of these compounds through single X-ray diffraction, and characterized them via elemental analysis, IR, TG and UV. Magnetic properties of these new compounds were studied in the range from 2 to 300K.1. Two new lanthanide polyoxometalates based on [γ-GeW₁₀O₃₆]^8- were successfully synthesized: Na₁₂[Dy₄(α-GeW₁₀O₃₈)₂（H₂O）₆]·36H₂O （1） Na₁₂[Er₄(α-GeW₁₀O₃₈)₂（H₂O）₆]·29H₂O （2） Compound 1 is isomorphous with 2. In these two compounds, four lanthanide ions were located in the central belt between two [α（1,4）-GeW₁₀O₃₈]^12- units. Meanwhile, each lanthanide ion resides in the vacant site of the [α（1,4）-GeW₁₀O₃₈]^12- fragment through bonding to five oxygen atoms, four of which are from the WO6 octahedra, while the other one is from central GeO₄ tetrahedron group. Compounds 1 and 2 are the first two examples of LnPOMs dimeric polyoxoanions accommodating four Ln³⁺ ions between two dilacunary Keggin-type polyanion units.2. On the basis of trivacant Keggin-type polyoxoaion [α-GeW₉O₃₄]^10-, a new 1:2 type structure of sandwich LnPOMs was isolated by adjusting proper pH of the reaction solution: （C₄H₉NO）(C₄H₁₀NO)₁₃[(GeW₁₁O₃₉)₂Nd]·9H₂O （3）3. On the basis of monovacant Keggin-type polyoxoaion [α-BW₁₁O₃₉]^9–, two classical structures of sandwich-type LnPOMs were synthesized in sodium acetate buffer solution: Na₂（C₃H₅N₂）₁₂H[(BW₁₁O₃₉)₂Pr]·7H₂O （4） K₂Na₆[N（CH₃）₄]₃H₄[(BW₁₁O₃₉)₂Dy]·23H₂O （5） In these two compounds, the polyanions [(BW₁₁O₃₉)₂Ln]^15- （Ln = Pr, Dy） are classic sandwich-type structure, where the Ln³⁺ ion is sandwiched by two monolacanary polyanions [α-BW₁₁O₃₉]^9–. Meanwhile, each monolacunary polyanion [α-BW₁₁O₃₉]^9– acts as an effective tetradentate coordinating with the Pr atom center through four unsaturated oxygen atoms. Furthermore, adjacent sandwich-type polyanions [(BW₁₁O₃₉)₂Pr]^15- of compound 4 are linked by [Na₂（C₃H₅N₂）₂]⁴⁺ units through O-Na-O bridges into a 2D layer parallel to the ab plane.更多还原