Phosphide Oxides RE2AuP2O (RE = La, Ce, Pr, Nd): Synthesis, Structure, Chemical Bonding, Magnetism, and 31P and 139La Solid State NMR

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• 作者：Timo Bartsch ; Thomas Wiegand ; Jinjun Ren ; Hellmut Eckert ; Dirk Johrendt ; Oliver Niehaus ; Matthias Eul ; Rainer P枚ttgen
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：February 18, 2013
• 年：2013
• 卷：52
• 期：4
• 页码：2094-2102
• 全文大小：431K
• 年卷期：v.52,no.4(February 18, 2013)
• ISSN：1520-510X

文摘

Polycrystalline samples of the phosphide oxides RE₂AuP₂O (RE = La, Ce, Pr, Nd) were obtained from mixtures of the rare earth elements, binary rare earth oxides, gold powder, and red phosphorus in sealed silica tubes. Small single crystals were grown in NaCl/KCl fluxes. The samples were studied by powder X-ray diffraction, and the structures were refined from single crystal diffractometer data: La₂AuP₂O type, space group C2/m, a = 1515.2(4), b = 424.63(8), c = 999.2(2) pm, 尾 = 130.90(2)掳, wR2 = 0.0410, 1050 F² values for Ce₂AuP₂O, and a = 1503.6(4), b = 422.77(8), c = 993.0(2) pm, 尾 = 130.88(2)掳, wR2 = 0.0401, 1037 F² values for Pr₂AuP₂O, and a = 1501.87(5), b = 420.85(5), c = 990.3(3) pm, 尾 = 131.12(1)掳, wR2 = 0.0944, 1143 F² values for Nd₂AuP₂O with 38 variables per refinement. The structures are composed of [RE₂O]⁴⁺ polycationic chains of cis-edge-sharing ORE_4/2 tetrahedra and polyanionic strands [AuP₂]^{4鈥?/sup>, which contain gold in almost trigonal鈥損lanar phosphorus coordination by P3鈥?/sup> and P₂4鈥?/sup> entities. The isolated phosphorus atoms and the P₂ pairs in La₂AuP₂O could clearly be distinguished by 31P solid state NMR spectroscopy and assigned on the basis of a double quantum NMR technique. Also, the two crystallographically inequivalent La sites could be distinguished by static 139La NMR in conjunction with theoretical electric field gradient calculations. Temperature-dependent magnetic susceptibility measurements show diamagnetic behavior for La₂AuP₂O. Ce₂AuP₂O and Pr₂AuP₂O are Curie鈥揥eiss paramagnets with experimental magnetic moments of 2.35 and 3.48 渭_B per rare earth atom, respectively. Their solid state 31P MAS NMR spectra are strongly influenced by paramagnetic interactions. Ce₂AuP₂O orders antiferromagnetically at 13.1(5) K and shows a metamagnetic transition at 11.5 kOe. Pr₂AuP₂O orders ferromagnetically at 7.0 K.}