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首页> 外文期刊>Current Inorganic Chemistry >Iron(III) Clusters from Polydentate Schiff Base Ligands: Involvement of Non Heisenberg Interaction in [(Fe~(III))_3(μ_2-OR)_3(μ_2-O_2CPh)_3]~(3+) Clusters
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Iron(III) Clusters from Polydentate Schiff Base Ligands: Involvement of Non Heisenberg Interaction in [(Fe~(III))_3(μ_2-OR)_3(μ_2-O_2CPh)_3]~(3+) Clusters

机译：来自多弥敦席夫碱配体的铁（III）簇：[（Fe〜（III））_ 3（μ_2-o_2cph）_3]〜（3+）集群中的非Heisenberg相互作用的参与

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摘要

Background: The considerable interest in iron(III) oxo/hydroxo brigded polynuclear complexes stems from their relevance to diverse fields, from bioinorganic chemistry to molecular magnetic materials. The trinuclear oxo-centered carboxylato iron complexes have been extensively used as simple models in order to understand the magnetic interactions which have been interpreted in terms of the Heisenberg-Dirac-van Vleck irotropic spin Hamiltonian with antiferromagnetic interactions as well as non-Heisenberg interactions such as antisymmetric exchange. Objectives: The main objective of this work was to study the magnetic interactions in triangular non oxocentered iron(III) complexes, a class of complexes which has been scarcely investigated so far. Methods: Reactions of Schiff base ligands, OH-C_(10)H_6-CH=NC(CH_2OH)_3, H_4L1, and OH-C_6H_4-CH=NC(R) (CH_2OH)_2 (R = CH_3, H_3L2; R = C_2H_5, H_3L3) with 'basic' iron(III) benzoate salts afforded two trinuclear complexes, [Fe_3(H_2L1)_3(O_2CPh)_3]·2CH_2Cl_2 (1·2CH_2Cl_2) and [Fe_3(HL2)_3(O_2CPh)_3]·0.45CH_2Cl_2·0.40-H_2O (2·0.45CH_2Cl_2·0.40H_2O), and four octanuclear clusters, [Fe_8(L3)_8(HO_2CPh)_2]·2.7CH_2Cl_2·7.2H_2O (3·2.7CH_2Cl_2·7.2H_2O), [Fe_8(L3)_6(HL3)_2 (O_2CPh)_2]·3THF (4·3THF), [Fe_8(L3)_6(HL3)_2(O_2CPh)_2]·6Me_2CO (5·6Me_2CO) and [Fe_8(L3)_6(HL3)_2 (O_2CPh)_2]·4dmf (6·4dmf). The crystal structures of 1-6 were determined by single-crystal X-ray crystallography. Variable-temperature magnetic susceptibility and magnetization measurements as well as Mossbauer spectra of 1-4 were undertaken. The study of the magnetic interactions within the trinuclear 1-2 was completed by X-band EPR spectroscopy. Results: The molecular structure of the trinuclear complexes 1 and 2 possesses a [(Fe~(III))_3(μ_2-OR)_3(μ_2-O_2CPh)_3]~(3+) core with the three Fe~(III) atoms located at the vertexes of a scalene triangle; this triangular topology missing a central μ_3-oxo bridge is rare in the literature. The octanuclear complexes 3-6 consist of seven corner-sharing [Fe_2(μ_2-OR)_2] units, alternatively described as two sets of three comer-sharing [Fe_2(μ_2-OR)_2] units in cisorientation linked through two μ_2-OR atoms; this metal topology is novel in Fe~(III) chemistry. The ~(57)Fe Mossbauer spectra of 1-4 are consistent with the presence of high spin ferric ions in octahedral environments. The magnetic studies of the trinuclear 1 and 2 revealed antiferromagnetic interactions with isotropic exchange parameters consistent with literature values. EPR spectroscopy revealed that the S_T = 1/2 state is highly anisotropic which is interpreted considering the non-Heisenberg terms zero field splitting and antisymmetric exchange. The magnetic studies of the octanuclear 3 and 4 revealed dominant antiferromagnetic interactions. Conclusion: This work presents the use of Schiff base ligands in iron(III)/carboxylato chemistry which afforded two trinuclear non oxo-centered (1, 2) and four octanuclear (3-6) complexes. A detailed magnetic and spectroscopic (EPR, Mossbauer) study of the extremely rare triangular non oxo-centered iron(III) complexes 1 and 2 revealed the role of non Heisenberg interactions.
机译：背景：铁（III）氧代/羟基分发多核络合物对铁（III）的相当兴趣源于与不同领域的相关性，从生物碳化物化学到分子磁性材料。三核以羰中心羧基铁复合物被广泛地用作简单的模型，以了解在Heisenberg-diac-van Vleck的IroTropic Spin Hamiltonian与反铁磁相互作用以及非Heisenberg相互作用的磁相互作用作为反对称交换。目的：这项工作的主要目的是研究三角形非致致浓铁（III）复合物中的磁相互作用，这是到目前为止几乎没有调查的一类复合物。方法：Schiff碱配体的反应，OH-C_（10）H_6-CH = NC（CH_2OH）_3，H_4L1和OH-C_6H_4-CH = NC（R）（CH_2OH）_2（R = CH_3，H_3L2; R = C_2H_5，H_3L3）与“基础”铁（III）苯甲酸盐得到两种三核复合物，[Fe_3（H_2L1）_3（O_2CPH）_3]·2CH_2CL_2（1·2CH_2CL_2）和[FE_3（HL2）_3（O_2CPH）_3]· 0.45CH_2CL_2·0.40-H_2O（2·0.45ch_2CL_2·0.40H_2O）和四个八核簇，[FE_8（L3）_8（HO_2CPH）_2]·2.7CH_2CL_2·7.2H_2O（3·2.7CH_2CL_2·7.2H_2O），[FE_8 （L3）_6（HL3）_2（O_2CPH）_2]·3thf（4·3thf），[FE_8（L3）_6（HL3）_2（O_2CPH）_2]·6ME_2CO（5·6ME_2CO）和[FE_8（L3）_6 （HL3）_2（O_2CPH）_2·4DMF（6·4DMF）。通过单晶X射线晶体学确定1-6的晶体结构。可变温度磁化率和磁化测量以及1-4的莫斯贝尔光谱。通过X波段EPR光谱完成三核1-2内的磁性相互作用的研究。结果：三核复合物1和2的分子结构具有[（Fe〜（III））_ 3（μ_2-或）_3（μ_2-o_2cph）_3]〜（3+）核心，三Fe〜（III）原子位于切割三角形的顶点;这个三角形拓扑缺少核心μ_3-氧代桥在文献中很少见。 OctAnuclecleClees 3-6由七个角分层[fe_2（μ_2-或）_2]组成，可选地描述为通过两个μ_2链接的CISorientation中的两组三种Comer共享[FE_2（μ_2-或）_2]或原子;这种金属拓扑在Fe〜（III）化学中是新颖的。 1-4的〜（57）FESBOSBAUER光谱与八面体环境中的高旋转铁离子的存在一致。三核1和2的磁性研究揭示了与各向同性交换参数与文献值一致的反铁磁相互作用。 EPR光谱表明，S_T = 1/2状态是高度各向异性的，其被解释为考虑非Heisenberg术语零场分裂和反对称交换。八季核3和4的磁性研究显示了显性的反铁磁相互作用。结论：这项工作介绍了使用铁（III）/羧酸盐化学中的Schiff碱配体，其提供了两个三核非以氧代（1,2）和四个辛核（3-6）络合物。极罕见的三角形非以氧代铁（III）复合物1和2的详细磁性和光谱（EPR，MOSSBAUER）研究显示了非HEISENBERG相互作用的作用。

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