Wassermann K, Pope M T
Department of Chemistry, Box 571227, Georgetown University, Washington, DC 20057-1227, USA.
Inorg Chem. 2001 Jun 4;40(12):2763-8. doi: 10.1021/ic001233u.
Several new large polyoxotungstates have been synthesized by reaction of lanthanide cations with the well-known "As(4)W(40)" anion, (B-alpha-AsO(3)W(9)O(30))(4)(WO(2))(4) (1). The heteropolyanions (H(2)O)(11)Ln(III)(Ln(III)(2)OH)(B-alpha-AsO(3)W(9)O(30))(4)(WO(2))(4)(-) (Ln = Ce, Nd, Sm, Gd) (2-4) (Ln(3)As(4)W(40)) and M(m)()(H(2)O)(10)(Ln(III)(2)OH)(2)(B-alpha-AsO(3)W(9)O(30))(4)(WO(2))(4) (Ln = La, Ce, Gd and M = Ba, K, none) (5-7) (Ln(4)As(4)W(40)) have been isolated as alkali metal and ammonium salts, respectively, and characterized by single-crystal X-ray analysis, elemental analysis, and IR and (183)W-NMR spectroscopy. The X-ray analyses revealed interanionic W-O-Ln bonds between adjacent Ln(x)()As(4)W(40) units forming a "dimer" for x = 3 and chains for x = 4. Upon dissolving in water these bonds hydrolyze and the monomeric species form. The straightforward syntheses which require the use of concentrated NaCl solutions (1-4 M) and the addition of stoichiometric amounts of Ba(2+) or K(+) reemphasize the importance of the presence of appropriate countercations for the assembly of large polyoxometalate structures.
通过镧系阳离子与著名的“As(4)W(40)”阴离子(B-α-AsO(3)W(9)O(30))(4)(WO(2))(4)(1)反应，合成了几种新型的大尺寸多金属氧酸盐。杂多阴离子(H(2)O)(11)Ln(III)(Ln(III)(2)OH)(B-α-AsO(3)W(9)O(30))(4)(WO(2))(4)(Ln = Ce、Nd、Sm、Gd)(2 - 4)(Ln(3)As(4)W(40))和[M(m)()(H(2)O)(10)(Ln(III)(2)OH)(2)(B-α-AsO(3)W(9)O(30))(4)(WO(2))(4)]((18 - m)(-))(Ln = La、Ce、Gd且M = Ba、K，无)(5 - 7)(Ln(4)As(4)W(40))分别作为碱金属盐和铵盐被分离出来，并通过单晶X射线分析、元素分析以及红外光谱和(183)W - NMR光谱进行了表征。X射线分析揭示了相邻Ln(x)()As(4)W(40)单元之间的阴离子间W - O - Ln键，当x = 3时形成“二聚体”，x = 4时形成链状结构。这些键在溶解于水时会水解并形成单体物种。需要使用浓NaCl溶液(1 - 4 M)并添加化学计量的Ba(2+)或K(+)的直接合成方法再次强调了适当抗衡阳离子对于大尺寸多金属氧酸盐结构组装的重要性。
