Vibrational properties of 1D- and 3D polynuclear spin crossover Fe(II) urea-triazoles polymer chains and quantification of intrachain cooperativity
Vibrational properties of 1D- and 3D polynuclear spin crossover Fe(II) urea-triazoles polymer chains and quantification of intrachain cooperativity
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一维和三维多核自旋交叉 Fe(II) 脲三唑聚合物链的振动特性和链内协同性的量化
DOI：
10.1088/1361-648x/aba71d
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发表时间：
2020
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影响因子：
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通讯作者：
V. Schünemann
中科院分区：
文献类型：
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作者：
J. Wolny;Tim Hochdörffer;S. Sadashivaiah;H. Auerbach;K. Jenni;L. Scherthan;Ai‐Min Li;C. von Malotki;H. Wille;E. Rentschler;V. Schünemann
利用同步加速器核非弹性散射研究了Fe(II) 4-烷基-尿素三唑链的一维和三维自旋交叉铁中心的振动动力学。对于一维系统，用密度泛函理论方法对声子态的偏密度进行了建模。此外，还得到了与自旋相关的铁配体距离和振动模式。先前引入的分子内协同性参数H coop （Rackwitz et al ., Phys.）。化学。化学。[Fe(n-Prtrzu)3(tosylate)2]的- 31 kJ mol−1和[Fe(n-Prtrzu)3(BF4)2]的+27 kJ mol−1。H coop中符号的变化符合前者自旋转变的不完全性和渐进式特征，以及后者的急剧转变（Rentschler和von Malotki， Inorg）。化学。， 2008年法案，361,3646)。这种效应可以归因于聚合物链的第二配位球中的分子内相互作用网络，这取决于铁中心的自旋状态。此外，通过分析涉及铁中心运动的分子模式，我们观察到具有急剧自旋跃迁的系统与具有不完全软跃迁的系统的耦合性和相干性降低。
The vibrational dynamics of the iron centres in 1D and 3D spin crossover Fe(II) 4-alkyl-urea triazole chains have been investigated by synchrotron based nuclear inelastic scattering. For the 1D system, the partial density of phonon states has been modelled with density functional theory methods. Furthermore, spin dependent iron ligand distances and vibrational modes were obtained. The previously introduced intramolecular cooperativity parameter H coop (Rackwitz et al, Phys. Chem. Chem. Phys. 2013, 15, 15450) has been determined to −31 kJ mol−1 for [Fe(n-Prtrzu)3(tosylate)2] and to +27 kJ mol−1 for [Fe(n-Prtrzu)3(BF4)2]. The change of sign in H coop is in line with the incomplete and gradual character of the spin transition for the former as well as with the sharp transition for the latter reported previously (Rentschler and von Malotki, Inorg. Chem., Act. 2008, 361, 3646). This effect can be ascribed to the networks of intramolecular interactions in the second coordination sphere of the polymer chains, depending on the spin state of the iron centres. In addition, we observe a decreased coupling and coherence when comparing the system which displays a sharp spin transition to the system with an incomplete soft transition by analyzing molecular modes involving a movement of the iron centres.