Cupric Siliconiobate. Synthesis and Solid-State Studies of a Pseudosandwich-Type Heteropolyanion

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• 作者：Travis M. Anderson ; Todd M. Alam ; Mark A. Rodriguez ; Joel N. Bixler ; Wenqian Xu ; John B. Parise ; May Nyman
• 刊名：Inorganic Chemistry
• 出版年：2008
• 出版时间：September 1, 2008
• 年：2008
• 卷：47
• 期：17
• 页码：7834-7839
• 全文大小：211K
• 年卷期：v.47,no.17(September 1, 2008)
• ISSN：1520-510X

文摘

The Na⁺ and [Cu(en)₂(H₂O)₂]²⁺ (en = ethylenediamine) salt of a pseudosandwich-type heteropolyniobate forms upon prolonged heating of Cu(NO₃)₂ and hydrated Na₁₄[(SiOH)₂Si₂Nb₁₆O₅₄] in a mixed water−en solution. The structure [a = 14.992(2) Å, b = 25.426(4) Å, c = 30.046(4) Å, orthorhombic, Pnn2, R1 = 6.04%, based on 25869 unique reflections] consists of two [Na(SiOH)₂Si₂Nb₁₆O₅₄]¹³⁻ units linked by six sodium cations, and this sandwich is charge-balanced by five [Cu(en)₂(H₂O)₂]²⁺ complexes, seven protons, and three additional sodium atoms (all per a sandwich-type cluster). Diffuse-reflectance UV−vis indicates that there is a λ_max at 383 nm for the Cu^II d−d transition and the ²⁹Si MAS NMR spectrum has two peaks at −78.2 ppm (151 Hz) and −75.5 ppm (257 Hz) for the two pairs of symmetry-equivalent internal [SiO₄]^4– and external [SiO₃(OH)]³⁻ tetrahedra, respectively. Unlike tungsten-based sandwich-type complexes, the [Na(SiOH)₂Si₂Nb₁₆O₅₄]¹³⁻ units are linked exclusively by Na⁺ instead of one or more d-electron metals.