Shylin Sergii I, Kucheriv Olesia I, Shova Sergiu, Ksenofontov Vadim, Tremel Wolfgang, Gural'skiy Il'ya A
Department of Chemistry, Taras Shevchenko National University of Kyiv, Volodymyrska 64, 01601 Kyiv, Ukraine.
Ångström Laboratory, Department of Chemistry, Uppsala University, P.O. Box 523, 75120 Uppsala, Sweden.
Inorg Chem. 2020 May 4;59(9):6541-6549. doi: 10.1021/acs.inorgchem.0c00627. Epub 2020 Apr 17.
Hofmann-like cyanometalates constitute a large class of spin-crossover iron(II) complexes with variable switching properties. However, it is not yet clearly understood how the temperature and cooperativity of a spin transition are influenced by their structure. In this paper, we report the synthesis and crystal structures of the metal-organic coordination polymers {Fe(Mepz)[Au(CN)]} () and {Fe(Mepz)[Ag(CN)]} (), where Mepz = 2-methylpyrazine, along with characterization of their spin-state behavior by variable-temperature SQUID magnetometry and Mössbauer spectroscopy. The compounds are built of cyanoheterometallic layers, which are pillared by the bridging Mepz ligands in but separated in . The complex exhibits an incomplete stepped spin transition as a function of the temperature with = 170 K and = 308 K for the two subsequent steps. In contrast, the complex attains the high-spin state over the whole temperature range. In the crystal structure of , weak interlayer contacts (Ag-π, Me-π, and Ag-N) are found that may be responsible for an unusual axial elongation of the FeN polyhedra. We propose that this structural distortion contributes to the trapping of iron in its high-spin state.
类霍夫曼氰基金属酸盐构成了一大类具有可变开关特性的自旋交叉铁（II）配合物。然而，自旋转变的温度和协同性如何受其结构影响，目前尚不清楚。在本文中，我们报道了金属有机配位聚合物{Fe(Mepz)[Au(CN)]}（）和{Fe(Mepz)[Ag(CN)]}（）的合成及晶体结构，其中Mepz = 2 - 甲基吡嗪，同时通过变温超导量子干涉仪磁力测定法和穆斯堡尔谱对它们的自旋态行为进行了表征。这些化合物由氰基异金属层构成，在中由桥连的Mepz配体支撑成柱状，但在中是分离的。配合物随温度呈现不完全的阶梯状自旋转变，两个后续步骤的分别为170 K和308 K。相比之下，配合物在整个温度范围内都处于高自旋态。在的晶体结构中，发现了弱的层间接触（Ag - π、Me - π和Ag - N），这可能是FeN多面体异常轴向伸长的原因。我们认为这种结构畸变有助于将铁捕获在其高自旋态。
