Synthesis and Characterization of [(OH)TeNb5O18]6‿/sup> in Water Solution, Comparison with [Nb6O19]8‿/sup>

详细信息    查看全文

• 作者：Pavel A. Abramov ; Tatiana P. Zemerova ; Nikolay K. Moroz ; Nikolay B. Kompankov ; Artem A. Zhdanov ; Alfiya R. Tsygankova ; Cristian Vicent ; Maxim N. Sokolov
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：February 15, 2016
• 年：2016
• 卷：55
• 期：4
• 页码：1381-1389
• 全文大小：477K
• ISSN：1520-510X

文摘

Reaction of [Nb₆O₁₉]^8– with H₆TeO₆ in water gives telluropentaniobate [(OH)TeNb₅O₁₈]^6– (1) as single product, which was isolated as Na⁺ and mixed Na⁺/K⁺ salts. Crystal structures were determined for Na₆[(OH)TeNb₅O₁₈]·15H₂O (Na₆-1) and K₆Na[Nb_5.5{Te(OH)}_0.5O_18.5]·26H₂O (K₆Na-1). Formation of 1 was monitored with electrospray ionization mass spectrometry (ESI-MS) and ¹²⁵Te NMR techniques. Capillary electrophoresis was used to calculate electrophoretic mobilities and radii of the anionic species in solutions of [(OH)TeNb₅O₁₈]^6– and [Nb₆O₁₉]^8– in borate buffer. No condensation or degradation products were detected. Reactions of 1 with {Cp*Rh}²⁺ sources gives 1:1 and 2:1 hybrid polyoxometalate, which are present in solution as a mixture of isomers, as detected by ¹²⁵Te NMR. The isomerism is related to various possibilities of coordination of {Cp*Rh}²⁺ to different {M₃O₃} faces, relative to the unique Te atom. According to ESI-MS experiments in water and methanol, rapid redistribution of the organometallic fragments between the 1:1 and 2:1 complexes takes place. The 1:1 complexes are more stable in water, while 2:1 complexes dominate in methanol. X-ray structural analysis of the crystals isolated from 2:1 reaction mixture allowed identification of Na₃[{Cp*Rh}₂TeNb₅O₁₉]·24H₂O (Cp*₂Rh₂-1) with two {Cp*Rh}²⁺ fragments capping the opposing faces of the Lindqvist anion.