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首页> 外文期刊>Bulletin of the Chemical Society of Japan >Fastener Effect on Uniaxial Chemical Pressure for One-Dimensional Spin-Crossover System, [Fe-II(NH2-trz)(3)](CnH2n+1SO3)(2)center dot xH(2)O: Magnetostructural Correlation and Ligand Field Analysis
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Fastener Effect on Uniaxial Chemical Pressure for One-Dimensional Spin-Crossover System, [Fe-II(NH2-trz)(3)](CnH2n+1SO3)(2)center dot xH(2)O: Magnetostructural Correlation and Ligand Field Analysis

机译：紧固件对单轴化学压力的一维旋转交叉系统，[Fe-II（NH2-TRZ）（3）]（CNH2N + 1SO3）（2）中央点XH（2）O：磁增生相关和配体场分析

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One-dimensional spin-crossover (SCO) polymers of formula [Fe-II(NH2-trz)(3)](CnH2n+1SO3)(2)center dot xH(2)O (trz: 4-substituted-1,2,4-triazole; n = 1-9) have been synthesized. They displayed hysteretic SCO transition around 280-350 K. The spin transition temperatures (T-1/2) in the heating and cooling processes increased, and the hysteresis width became narrower with increasing alkyl chain length (n). From the analysis of EXAFS, the nearest-neighbor Fe-Fe distance decreased with increasing n, and it had a close relationship with T-1/2. This is highly indicative of the increase of intrachain interaction of [Fe-II(NH2-trz)(3)] with n being attributed to the uniaxial chemical pressure effect induced by van der Waals force between alkyl chains, so-called "fastener effect." To elucidate the physicochemical effect on Tip, the ligand field and Racah parameter (B) were estimated by analysing the pre-edge region in Fe-K edge XANES spectra based on the ligand-field theory. B decreased with increasing n, which was closely consistent with the behavior of T-1/2 and Fe-57 Mossbauer isomer shift (IS). Judging from these results, a covalency between Fe-II 3d and ligand pi* orbital is enhanced by the fastener effect, leading to the expansion of the 3d orbital, i.e. the remarkable decrease of B and IS, which is the dominating factor on T-1/2 in our system.
机译：式[Fe-II（NH 2-TRZ）（3）]（CNH2N + 1SO3）（2）中心点XH（2）O（TRZ：4替代-1,2已经合成了4-三唑; n = 1-9）。它们显示在280-350克左右的滞后SCO转换。加热和冷却过程中的旋转过渡温度（T-1/2）增加，并且滞后宽度随着烷基链长度的增加而变窄（n）。根据EXAFS的分析，最近的邻居Fe-Fe距离随着N增加而降低，它与T-1/2有密切的关系。这对于[Fe-II（NH2-TRZ）（3）]的颈内相互作用的增加具有n致力于由烷基链之间的烷基链，所谓的“紧固件效应”致力于Unizial化学压力效应。“为了阐明对尖端的物理化学效果，通过基于配体场理论分析Fe-K边缘Xanes光谱中的预先边缘区域来估计配体场和Racah参数（B）。 B随着N的增加而下降，这与T-1/2和Fe-57莫斯巴尔异构体换档（是）的行为密切一致。从这些结果判断，通过紧固件效应增强了Fe-II 3D和配体Pi *轨道之间的共价，导致3D轨道的膨胀，即B的显着降低，是T-的主导因素1/2在我们的系统中。

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