After solid‐state reactions of the light lanthanoid metals, their oxides and fluorides as well as selenium in sealed tantalum ampoules with sodium chloride as a fluxing agent at 850 °C for 8 days needle‐shaped single crystals of Ln₃F₂Se₂TaO₄ (Ln = La – Nd) were obtained. They crystallize in the orthorhombic space group Pnma analogous to La₃F₂Se₂NbO₄ with a = 1133–1120 pm, b = 400–393 pm and c = 1812–1778 pm (Ln = La – Nd) for Z = 4 as the first known quinary lanthanoid(III) oxoselenotantalates(V) with fluoride and selenide anions. The three crystallographically different Ln³⁺ cations are all surrounded by nine anions (O^2–, F^– and Se^2–) each. Tantalum resides in an octahedral chalcogen coordination by forming trans‐vertex oxygen‐connected [TaO₅Se]^7– polyhedra, which build up chains ¹_∞{[TaO^V_2/2O^t_3/1Se^t_1/1]^5–} along [010]. The sites of the four crystallographically different oxygen atoms and the two distinct fluoride anions were established by bond‐valence calculations. One fluorine and three oxygen atoms are surrounded tetrahedrally by cations, while another fluoride and oxide anion exhibit just triangular non‐planar coordination spheres. The two independent Se^2– anions have five or six cationic neighbors.

中文翻译：

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关于成分为Ln3F2Se2TaO4（Ln = La – Nd）的镧系元素氟化硒硒代壬酸酯

在密封的钽安瓿瓶中，用氯化钠作为助熔剂，于850°C下将轻质镧系金属，其氧化物和氟化物以及硒进行固态反应，历经8天，形成Ln ₃ F ₂ Se ₂ TaO针状单晶_获得4（Ln = La – Nd）。它们在结晶的斜方晶系空间群晶Pnma类似的La ₃ ˚F ₂硒₂的NbO ₄与一个= 1133年至1120年时，b = 400-393 PM和C ^ = 1812至1778年时（LN = LA -钕），用于Ž= 4是第一个已知的含氟和硒化物阴离子的喹啉镧系（III）氧代壬酸酯（V）。三种晶体学上不同的Ln ³⁺阳离子均被9个阴离子（O ^2–，F ^–和Se ^2–）包围。钽驻留在八面体配位的硫属元素通过形成反式-点氧连接的[的TaO ₅硒] ^7-多面体，其堆积链¹ _∞ {[的TaO ^V _2/2 ö^吨_3/1硒^吨_1/1 ] ^5-}，沿[010]。通过键合价计算确定了四个晶体学上不同的氧原子和两个不同的氟阴离子的位点。一个氟和三个氧原子被阳离子四面体包围，而另一个氟和氧化物阴离子仅表现出三角形的非平面配位球。两个独立的Se ^2–阴离子具有五个或六个阳离子邻居。