Correlation among the structural, electronic and magnetic properties of [Fe4(.mu.3-S)3(.mu.3-S2)Cp4]n+ (n = 0-2) clusters at various oxidation states
Correlation among the structural, electronic and magnetic properties of [Fe4(.mu.3-S)3(.mu.3-S2)Cp4]n+ (n = 0-2) clusters at various oxidation states
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[Fe4(.mu.3-S)3(.mu.3-S2)Cp4]n (n = 0-2)团簇在不同氧化态下的结构、电子和磁性之间的相关性
DOI：
10.1021/ic00229a020
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发表时间：
1986
影响因子：
4.6
通讯作者：
J. Jordanov
中科院分区：
文献类型：
--
作者：
N. Dupré;P. Auric;H. Hendriks;J. Jordanov
详细描述了[Fe4(M3-S)3(U3-S2)Cp4][Pf6]2-乙醇(III)。配合物III(C22H26F12Fe4OP2S5)属正交晶系空间群Pbca，晶胞常数为a=13.494(3)，b=27.193(8)，c=17.529(6)，V=17.529×3，Z=8。与单定位一样，保留了Fe4S5核心。然而，两个Fe-Fe距离发生了显著的收缩，从2.723和2.866 Arin II到2.661和2.650 Arin III。此外，在Fe(2)位，存在较高的局部对称性，其中斜镜平面平分由Fe(2)、S(5)、Fe(4)和Fe(2)、S(5)、Fe(L)两个核面确定的二面角。对系列的对比分析表明，在连续还原(或氧化)过程中，最显著的结构变化发生在Fe(L)、Fe(2)和Fe(4)位，而不是在五配位的Fe(3)位。化合物I、II和III在1.8K的零场穆斯堡尔谱由三个相对强度为2：1：1的四极偶组成。氧化过程中，三个四配位的铁的平均异构体移动值减小，而五配位的铁基本上不受氧化过程的影响。在外加磁场(H0和lt；100kOe)作用下，1.8K顺磁单点的穆斯堡尔谱表明，在铁核上存在一个非常小(小于10kOe)的超精细场。在化合物II的~1H和~(13)C核磁共振谱中，没有检测到环戊二烯基共振峰的各向同性位移。这些观察结果使我们得出结论，未配对的电子自旋密度肯定主要集中在Fe4S5核的硫原子上。
[Fe4 (M3-S) 3 (u3-S2) Cp4][PF6] 2-EtOH (III) is described in detail. Complex III (C22H26F12Fe4OP2S5) crystallizes in the orthorhombic space group Pbca with cell constants a= 13.494 (3) Á, b= 27.193 (8) Á, c= 17.529 (6) Á, V= 6432.2 Á3, and Z= 8. Refinement by full-matrix least squares of 431 parameters on 4666 data gave a final R value of 0.064. The Fe4S5 core is retained, as in the monocation. A significant contraction of two Fe-Fe distances has occurred however, from 2.723 and 2.866 Á in II to 2.661 and 2.650 Á in III. Moreover, a higher local symmetry is presentin the dication at the Fe (2) site, where a diagonal mirror plane bisects the dihedral angle defined by the two core faces Fe (2), S (5), Fe (4) and Fe (2), S (5), Fe (l). Comparative analysis over the series shows that, uponsuccessive reduction (or oxidation), the most significant structural changes occur at Fe (l), Fe (2), and Fe (4) but not at the five-coordinated Fe (3) site. Zero-field Mossbauer spectra of compounds I, II, and III at 1.8 K consist of three quadrupole doublets of 2: 1: 1 relative intensities. The average isomer shift values of the three tetracoordinated iron sites decrease upon oxidation, whereas the five-coordinated iron remains essentially unaffected by the same process. Mossbauer spectra of the paramagnetic monocation at 1.8 K withapplied magnetic fields (H0< 100 kOe) indicate the presence of a very small (less than 10 kOe) hyperfine field at the iron nuclei. No isotropic shifts of the cyclopentadienyl resonances in the* H and 13C NMR spectra of compound II are detected. These observations led us to conclude that the unpaired electron spin density must be predominantly localized on the sulfur atoms of the Fe4S5 core.