Magnetic Properties of Novel Dendrimeric Spin Crossover Iron(III) Complex.
Magnetic Properties of Novel Dendrimeric Spin Crossover Iron(III) Complex.
复制标题
新型树枝状自旋交叉铁(III)络合物的磁性。
DOI：
10.1016/j.ica.2015.10.024
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发表时间：
2016
影响因子：
2.8
通讯作者：
A.
中科院分区：
文献类型：
--
作者：
Domracheva;N.;Vorobeva;V.;Pyataev;A.;Tamura;R.;Suzuki;K.;Gruzdev;M.;Chervonova;U.;Kolker;A.
新型树枝状自旋交叉Fe（III）配合物[Fe（L）2]+ PF 6-（L= 3，5-di）的合成和磁性研究首次用磁化率法研究了3，4，5-三（十四烷氧基）苯甲酰基-4-氧基水杨醛-N′-乙基-N-乙二胺，宽温度范围（2-300 K）的电子顺磁共振（EPR）和穆斯堡尔谱。EPR研究表明，该化合物是磁性不均匀的，由两个磁性亚晶格组成，在160 K以上有约25%的Fe（III）分子发生部分自旋交叉（S= 5/2惠1/2），在10 K以下发生反铁磁（AF）有序.高自旋（HS，S= 5/2）Fe（III）中心与弱扭曲的八面体环境最有可能形成链层。由低自旋（LS，S= 1/2）中心和具有强烈畸变八面体环境的HS中心形成的二聚体分子可能位于层之间并且参与自旋交叉。EPR已经显示了在高温（70-300 K）范围内AF动态自旋团簇的存在，这在短时间尺度（10 - 10 s）内是可见的，并且不能在静态磁测量中记录。穆斯堡尔谱表明，在顺磁状态下的化合物的四极偶极子与平均异构体位移为0.35毫米/秒和分裂0.72毫米/秒对应的HS Fe（III）中心。在60 K以下，谱图显示出磁性超精细结构的出现，其弛豫性质证明了材料中小团簇的集体自旋翻转。穆斯堡尔谱学证实了在5 K下Fe（III）树枝状复合物中AF有序的存在。
The synthesis and magnetic properties of novel dendrimeric spin crossover Fe (III) complex of formula [Fe (L) 2]+ PF 6−, where L= 3, 5-di (3, 4, 5-tris (tetradecyloxy) benzoyloxy) benzoyl-4-oxy-salicylidene-N′-ethyl-N-ethylenediamine have been studied for the first time by magnetic susceptibility, Electron Paramagnetic Resonance (EPR) and Mössbauer spectroscopy in the wide (2–300 K) temperature range. EPR showed that the compound is magnetically inhomogeneous, consists of two magnetic sub-lattices, displays a partial spin crossover (S= 5/2⇔ 1/2) of∼ 25% of the Fe (III) molecules above 160 K and undergoes the antiferromagnetic (AF) ordering below 10 K. High-spin (HS, S= 5/2) Fe (III) centers with weakly distorted octahedral environment most probably form chains in layers. The dimeric molecules, formed from low-spin (LS, S= 1/2) centers and HS centers with strongly distorted octahedral environment are likely located between the layers and are involved in the spin crossover. EPR has shown the presence of AF dynamical spin clusters in the high temperature (70–300 K) range, which are visible in the short time scale (10− 10 s) and could not be registered in the static magnetic measurements. Mössbauer spectra demonstrated in a paramagnetic state of the compound a quadrupole doublet with average isomer shift of 0.35 mm/s and splitting 0.72 mm/s corresponding to HS Fe (III) centers. Below 60 K, the spectra displayed the appearance of magnetic hyperfine structure, whose relaxation nature testifies the collective spin flips of small clusters in the material. Mössbauer spectroscopy confirmed the existence of AF ordering in the Fe (III) dendrimeric complex at 5 K.