Synthesis, Physical Properties, and Theoretical Study of R16Mo21O56 Compounds (R = La, Ce, Pr, and Nd) Containing Bioctahedral Mo10 Clusters and Single Mo A

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• 作者：Philippe Gall ; Ré ; gis Gautier ; Jean-Franç ; ois Halet ; and Patrick Gougeon
• 刊名：Inorganic Chemistry
• 出版年：1999
• 出版时间：October 4, 1999
• 年：1999
• 卷：38
• 期：20
• 页码：4455 - 4461
• 全文大小：129K
• 年卷期：v.38,no.20(October 4, 1999)
• ISSN：1520-510X

文摘

Polycrystalline samples and single crystals of R₁₆Mo₂₁O₅₆ compounds (R = La, Ce, Pr, and Nd) were synthesizedby solid-state reactions at high temperature in sealed Mo crucibles. The structure of La₁₆Mo₂₁O₅₆ was determinedby single-crystal X-ray diffraction methods. It crystallizes in a monoclinic lattice, P2₁/c, with a = 13.532(2) Å,b = 13.464(1) Å, c = 13.447(1) Å, = 99.681(7), and Z = 2. It is isostructural to Ce₁₆Mo₂₁O₅₆ and Nd₁₆Mo₂₁O₅₆ previously reported. The R₁₆Mo₂₁O₅₆ compounds contain bioctahedral Mo₁₀ clusters and MoO₆octahedral units linked together via oxygen bridges. Magnetic susceptibility measurements indicate that the oxidationstate of the single Mo atoms is +4 and that of the Ce and Pr atoms is +3, affording 30 metallic valence electronsto the Mo₁₀ nonmagnetic clusters. Such an electron count per Mo₁₀ cluster is confirmed by molecular calculationsperformed on an isolated Mo₁₀ cluster unit. Resistivity measurements and extented Hückel tight-bindingcalculations show that the R₁₆Mo₂₁O₅₆ compounds are insulating materials.