Department of Inorganic Chemistry, Kazan State Technological University, Kazan, Russia.
Inorg Chem. 2011 Feb 7;50(3):1021-9. doi: 10.1021/ic101691q. Epub 2010 Dec 28.
Six [Fe(8)(μ(4)-O)(4)(μ-4-R-pyrazolato)(12)X(4)] complexes containing an identical Fe(8)(μ(4)-O)(4) core have been structurally characterized and studied by Mössbauer spectroscopy. In each case, an inner μ(4)-O bridged Fe(III) cubane core is surrounded by four trigonal bipyramidal iron centers, the two distinct sites occurring in a 1:1 ratio. The Mössbauer spectrum of each of the clusters consists of two quadrupole doublets, which, with one exception (X = NCS, R = H), overlap to give three absorption lines. The systematic variation of X and R causes significant changes in the Mössbauer spectra. A comparison with values for the same clusters computed using density functional theory allows us to establish an unequivocal assignment of these peaks in terms of a nested model for the overlapping doublets. The changes in Mössbauer parameters (both experimental and computed) for the 1-electron reduced species Fe(8)(μ(4)-O)(4)(μ-4-Cl-pyrazolato)(12)Cl(4) are consistent with a redox event that is localized within the cubane core.
六个含有相同 Fe(8)(μ(4)-O)(4)核心的 [Fe(8)(μ(4)-O)(4)(μ-4-R-pyrazolato)(12)X(4)] 配合物已通过 Mössbauer 光谱学进行了结构表征和研究。在每种情况下，一个内部 μ(4)-O 桥接的 Fe(III)立方烷核心被四个三角双锥铁中心包围，两个不同的位置以 1:1 的比例出现。每个簇的 Mössbauer 光谱由两个四极子双峰组成，除了一个例外（X = NCS，R = H），它们重叠形成三个吸收线。X 和 R 的系统变化导致 Mössbauer 光谱发生显著变化。与使用密度泛函理论计算的相同簇的值进行比较，使我们能够根据嵌套模型对重叠双峰进行明确的峰分配。对于 1 电子还原物种 Fe(8)(μ(4)-O)(4)(μ-4-Cl-pyrazolato)(12)Cl(4) 的 Mössbauer 参数（实验和计算）的变化与位于立方烷核心内的氧化还原事件一致。
