Spin‐crossover complexes form one of the biggest families of switchable compounds. Here we show a new way to obtain spin‐crossover materials by direct synthesis from metallic iron. Four complexes of Fe^II with 4‐R‐1,2,4‐triazoles have been synthesized by a direct metal oxidation: [Fe(NH₂trz)₃]SO₄, [Fe(NH₂trz)₃](BF₄)₂ and two polymorphs of [Fe(Htrz)₂(trz)]BF₄. Surprisingly high quality of PXRD pattern of [Fe(NH₂trz)₃]SO₄ allowed to perform Rietveld refinement and obtain reliable crystal structure of the latter. All compounds have been studied by magnetic susceptibility measurements, optical reflectivity, differential scanning calorimetry and Raman spectroscopy. Importantly, spin‐crossover characteristics of the complexes obtained by this unusual method are preserved, thus revealing a new effective approach of “direct synthesis” towards switchable coordination compounds.

中文翻译：

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自旋交叉配合物的直接合成：意外揭示的新铁三唑结构。

自旋交联复合物是最大的可切换化合物家族之一。在这里，我们展示了一种由金属铁直接合成获得自旋交联材料的新方法。通过直接金属氧化合成了Fe ^II与4-R-1,2,4-三唑的四种配合物：[Fe（NH ₂ trz）₃ ] SO ₄，[Fe（NH ₂ trz）₃ ]（BF ₄）₂和[Fe（Htrz）₂（trz）] BF _4的两个多晶型物。[Fe（NH ₂ trz）₃ ] SO ₄的PXRD图谱的质量令人惊讶允许进行Rietveld精炼并获得后者的可靠晶体结构。通过磁化率测量，光反射率，差示扫描量热法和拉曼光谱研究了所有化合物。重要的是，保留了通过这种不同寻常的方法获得的复合物的自旋交叉特性，从而揭示了一种新的有效的“直接合成”向可转换配位化合物的方法。