Bassil Bassem S, Dickman Michael H, von der Kammer Bernd, Kortz Ulrich
School of Engineering and Science, International University Bremen, P.O. Box 750 561, 28725 Bremen, Germany.
Inorg Chem. 2007 Apr 2;46(7):2452-8. doi: 10.1021/ic061737d. Epub 2007 Mar 1.
We have synthesized and structurally characterized the monolanthanide-containing polyanions [Ln(beta2-SiW11O39)2]13- (Ln = La (1), Ce (2), Sm (3), Eu (4), Gd (5), Tb (6), Yb (7), Lu (8)). Synthesis was accomplished by reaction of the respective lanthanide ion with the monolacunary Keggin-type precursor [beta2-SiW11O39]8- in a 1:2 molar ratio in 1 M KCl medium at pH 5. Polyanions 1-8 were isolated as potassium salts and then characterized by IR, single-crystal X-ray diffraction, and elemental as well as thermogravimetric analysis. The structures of 1-8 are composed of an eight-coordinated Ln3+ center sandwiched by two chiral (beta2-SiW11O39) units. Large Ln3+ ions appear to favor an (R,R) (or (S,S)) configuration (point group C2) of the Keggin units, with an increasing amount of (R,S) (or (S,R)) configuration (point group C1) found in the solid state as the Ln3+ ion decreases in size. This trend is also supported by solution 183W NMR results for the diamagnetic La3+ and Lu3+ derivatives.
我们合成并通过结构表征了含单镧系元素的聚阴离子[Ln(β2-SiW11O39)2]13-（Ln = La (1)、Ce (2)、Sm (3)、Eu (4)、Gd (5)、Tb (6)、Yb (7)、Lu (8)）。合成是通过在pH为5的1 M KCl介质中，使相应的镧系离子与单缺位的Keggin型前体[β2-SiW11O39]8-以1:2的摩尔比反应来完成的。聚阴离子1 - 8以钾盐形式分离出来，然后通过红外光谱、单晶X射线衍射、元素分析以及热重分析进行表征。1 - 8的结构由一个八配位的Ln3+中心夹在两个手性(β2-SiW11O39)单元之间组成。大的Ln3+离子似乎有利于Keggin单元的(R,R)（或(S,S)）构型（点群C2），随着Ln3+离子尺寸减小，在固态中发现(R,S)（或(S,R)）构型（点群C1）的量增加。抗磁性的La3+和Lu3+衍生物的溶液183W NMR结果也支持了这一趋势。
