Unconventional Spin Crossover in Dinuclear and Trinuclear Iron(III) Complexes with Cyanido and Metallacyanido Bridges
Unconventional Spin Crossover in Dinuclear and Trinuclear Iron(III) Complexes with Cyanido and Metallacyanido Bridges
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DOI：
10.1002/ejic.200900169
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发表时间：
2009-07
影响因子：
2.3
通讯作者：
Ivan Šalitroš;R. Boča;L. Dlháň;M. Gembicky;J. Kožíšek;J. Linares;J. Moncol’;Ivan Nemec;L. Perašínová;F. Renz;I. Svoboda,;H. Fuess,
中科院分区：
文献类型：
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作者：
Ivan Šalitroš;R. Boča;L. Dlháň;M. Gembicky;J. Kožíšek;J. Linares;J. Moncol’;Ivan Nemec;L. Perašínová;F. Renz;I. Svoboda,;H. Fuess,
不对称三胺1，6-二氨基-4-氮杂己烷与(X-取代)邻水杨醛希夫缩合得到五齿配体X-L 5：SAMPET和MeBu-SAMPET。这些配体形成了单核、双核和三核的Fe III络合物，其结构由单晶X射线分析确定。在单核配合物中，[Fe III(硝基)氯]和[Fe III(硝酸乙酯)氯]是高自旋(S=5/2)，而[Fe III(硝基)CN]·甲醇是低自旋(S=1/2)。双核和三核配合物表现出一种热诱导的自旋交叉。二核配合物[L 5 Fe III(CN)Fe III L 5](ClO4)·2H2O(L 5)是一种混合自旋组装：在低温下，C配位的Fe III中心是低自旋(L)，N配位的Fe III中心是高自旋(H)，它们之间发生了反铁磁相互作用。该LH参考状态与L1参考状态混合。加热后，体系的HH态含量增加。双核配合物[L 5 Fe III(CN)Fe III L 5](BPh 4)·2MeCN(L 5=MeBu-salet)在L H和H H自旋对之间发生自旋跃迁.混价三核配合物[L 5 Fe III{Fe II(CN)5(NO)}Fe III L 5]·0.5MeOH·3.75H2O(L 5=硝基)在液氦温度下表现出自旋交叉和残留的高自旋分数，这是由于LL+Lh基态。金属氰基桥联配合物[L 5 Fe III{Ni(CN)4}Fe III L 5]·2MeOH(L 5=MeBu-salpt)在整个温度区间内含有一个高自旋对HH，具有铁磁交换作用。概述了一个理论模型，该模型允许所有可用的实验数据(磁化率、磁化强度、从穆斯堡尔谱获得的高自旋摩尔分数)在一组共同的参数上同时拟合。
A nonsymmetrical triamine, 1,6-diamino-4-azahexane, was Schiff-condensed with (X-substituted) o-salicylaldehyde to yield pentadentate ligands X-L 5 : salpet and MeBu-salpet. These ligands form mononuclear, dinuclear, and trinuclear Fe III complexes, whose structures were determined by single-crystal X-ray analysis. Of the mononuclear complexes, [Fe III (salpet)Cl] and [Fe III (MeBu-salpet)Cl] are high spin (S = 5/2), whereas [Fe III (salpet)CN]·MeOH is low spin (S = 1/2). The dinuclear and trinuclear complexes show a kind of thermally induced spin crossover. The dinuclear complex [L 5 Fe III (CN)Fe III L 5 ](ClO 4 )·2H 2 O (L 5 = salpet) is a mixed-spin assembly: the C-coordinated Fe III center is low spin (L) and the N-coordinated Fe III center is high spin (H) at low temperature ; an antiferromagnetic interaction occurs between them. This LH reference state is mixed with the LL one. Upon heating, the system shows an increasing content of the HH state. Also, the dinuclear complex [L 5 Fe III (CN)Fe III L 5 ](BPh 4 )· 2MeCN (L 5 = MeBu-salpet) exhibits a spin transition between LH and HH spin pairs. The mixed-valence trinuclear complex [L 5 Fe III {Fe II (CN) 5 (NO)}Fe III L 5 ]·0.5MeOH·3.75H 2 O (L 5 = salpet) shows spin crossover with a residual high-spin fraction at liquid He temperature owing to the LL + LH ground state. The metallacyanido-bridged complex [L 5 Fe III {Ni(CN) 4 }Fe III L 5 ]·2MeOH (L 5 = MeBu-salpet) contains a high-spin pair, HH, over the whole temperature interval with a ferromagnetic exchange interaction. A theoretical model was outlined that allows simultaneous fitting of all available experimental data (magnetic susceptibility, magnetization, high-spin mole fraction obtained from the Mossbauer spectra) on a common set of parameters.