Yellow single‐crystals of Na₂[Ir(OH)₆] were obtained by hydrothermal synthesis in 20 m sodium hydroxide solution at 473 K within 5 hours. X‐ray diffraction on a single‐crystal revealed the trigonal space group (no. 148) with lattice parameters a=582.76(3) pm and c=1399.30(8) pm at 100(1) K. Na₂[Ir(OH)₆] crystallizes in a hettotype of Mg(OH)₂ (brucite) and is isostructural to Na₂[Sn(OH)₆]. The oxygen atoms are arranged in a hexagonal close packing, Na⁺ and Ir⁴⁺ ions occupy the octahedral voids in every second layer in an ordered manner, the voids of the next layers remain empty. The hydroxidometalate layer can be seen as isolated [Ir(OH)₆]²⁻ octahedra, which are embedded in a honeycomb net of alkali metal cations. Temperature‐dependent magnetic measurements revealed paramagnetic behavior with an effective moment of 1.9 μ_B per iridium ion. The thermal decomposition of Na₂[Ir(OH)₆] in air starts at about 220 °C and results in pure Na₂IrO_3.

中文翻译：

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Na2 [Ir（OH）6]的水热合成，晶体结构和磁性及其脱水成Na2IrO3

Na ₂ [Ir（OH）₆ ]的黄色单晶是通过在20 m氢氧化钠溶液中于473 K在5小时内进行水热合成而获得的 。在单晶上的X射线衍射显示在100（1）K处晶格参数a = 582.76（3）pm和c = 1399.30（8）pm的三角空间群（148号）Na ₂ [Ir（OH ）₆ ]结晶为Mg（OH）₂（榴辉岩）的同型，并且与Na ₂ [Sn（OH）₆ ]同构。氧原子以六方密堆积Na ⁺和Ir ⁴⁺排列离子以有序的方式占据了第二层中的八面体空隙，下一层的空隙保持为空。羟基金属氧酸盐层可以看作是孤立的[Ir（OH）₆ ] ^2-八面体，埋在碱金属阳离子的蜂巢网中。温度依赖性磁测量显示与1.9μ的有效时刻顺磁性行为_乙每铱离子。Na ₂ [Ir（OH）₆ ]在空气中的热分解始于约220°C，并产生纯净的Na ₂ IrO _3。