Double exchange in a mixed-valent octanuclear iron cluster, [Fe8(µ4-O)4(µ-4-Cl-pz)12Cl4](-).
Double exchange in a mixed-valent octanuclear iron cluster, [Fe8(µ4-O)4(µ-4-Cl-pz)12Cl4](-).
复制标题
混合价八核铁簇中的双交换，[Fe8(µ4-O)4(µ-4-Cl-pz)12Cl4](-)。
DOI：
10.1039/c4dt00020j
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Zueva EM
中科院分区：
文献类型：
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作者：
Zueva EM
SQUID和脉冲高场磁强计的组合被用来探测混合价在FeIIFe7III集群的性质。DFT计算的自旋哈密顿参数表明，反铁磁耦合占主导地位，立方烷核心（t1）和立方烷和三个相邻的铁（t2）之间的四个铁之间的电子转移是显着的。使用计算参数的模拟能够再现在2 < T < 300 K温度范围内测量的有效磁矩μeff（T）的关键特征。相反，在0.4 K下测量的摩尔磁化强度Mmol的场依赖性与大量的电子转移不一致：只有t2 = 0的值将基态和第一激发态之间的分离放置在实验指示的区域中。在非常低的温度下的立方烷外电子转移的明显淬火表明，电子振动耦合产生一个或多个浅的最小值的绝热势能表面上，用于捕获的巡回电子在立方烷的核心。
A combination of SQUID and pulsed high-field magnetometry is used to probe the nature of mixed valency in an FeIIFe7III cluster. DFT-computed spin Hamiltonian parameters suggest that antiferromagnetic coupling dominates, and that electron transfer both between the four irons of the cubane core (t1) and between a cubane and three neighboring irons (t2) is significant. Simulations using the computed parameters are able to reproduce the key features of the measured effective magnetic moment, μeff(T), over the 2 < T < 300 K temperature range. In contrast, the field dependence of the molar magnetization, Mmol, measured at 0.4 K is inconsistent with substantial electron transfer: only values of t2 ∼ 0 place the separation between ground and first excited states in the region indicated by experiment. The apparent quenching of the cubane–outer electron transfer at very low temperatures indicates that vibronic coupling generates one or more shallow minima on the adiabatic potential energy surfaces that serve to trap the itinerant electron in the cubane core.