Synthesis and magnetic properties of mixed crystals of paramagnetic transition metal thiocyanato coordination polymers.

顺磁性过渡金属硫氰酸根配位聚合物混晶的合成及磁性能。

• 批准号: 290067379
• 负责人: Professor Dr. Christian Näther
• 金额: --
• 依托单位: Forschungsgruppe Festkörper- und Koordinationschemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/290067379?language=en
• 关键词: Synthesis; magnetic; properties; mixed; crystals

Recently, the development of strategies for a more rational synthesis of new coordination compounds with defined magnetic properties has become of increasing interest. Most compounds consists of only one kind of metal cation but there is also increasing interest for the preparation of bimetallic compounds. This can be achieved, e.g., by the reaction of anionic metal complexes with different metal cations. In contrast, the targeted synthesis of solid solutions with the major goal to modify the magnetic properties of coordination compounds in more detail was rarely used and this is exactly the content of the present project. Mixed crystals of compositions [M1xM21-x(NCS)2(L1)2]n and [M1xM21-x(NCS)2(L2)]n (M1, M2 = Mn(II), Fe(II), Co(II) and Ni(II); L1 = monodentate N-donor ligand; L2 = bridging N-donor) should be prepared and investigated for their composition, their homogeneity and their magnetic properties. Preliminary investigations have shown, that from solution no homogenous samples of the desired compounds can be obtained. Therefore, an alternative synthetic route was used, which was never used before for the synthesis of mixed crystals of coordination compounds. This strategy is based on the synthesis of precursors of composition [M1M21-x(NCS)2(L1)4]n and [M1xM21-x(NCS)2(L2)2]n, which finally are transformed into the desired compound by thermal decomposition. First results shows, that with this method homogenous mixed crystals consisting of Co and Ni can be prepared, that exhibits a composition, which exactly corresponds to that, used in the synthesis. On heating they transform quantitatively into the desired compounds. As shown by magnetic measurements, on thermal decomposition no phase separation take place, because these samples shows a magnetic behavior, which is completely different from that of the homometallic compounds. In this context it is noted that [Co(NCS)2(pyridine)2]n exhibits a ferromagnetic ground state and shows a slow relaxation of the magnetization, whereas [Ni(NCS)2(pyridine)2]n exhibits an antiferromagnetic ground state and shows a metamagnetic transition. In contrast, mixed crystals of composition [Co0.5Ni0.5(NCS)2(Pyridin)2]n shows a metamagnetic transition, which is typical for the pure Ni compound but in the antiferromagnetic phase slow relaxations are observed, which are typical for the pure Co compound. In the course of this project, it should be investigated if this synthetic tool can be used in general for the synthesis of mixed crystals of this class of compounds and which changes in the magnetic properties occur on mixed crystal formation.

近年来，发展策略，更合理地合成新的配合物与定义的磁性已成为越来越多的兴趣。大多数化合物仅由一种金属阳离子组成，但对双金属化合物的制备也越来越感兴趣。这可以通过以下方式实现，例如，通过阴离子金属络合物与不同金属阳离子的反应。相比之下，以更详细地修饰配位化合物的磁性为主要目标的固溶体的靶向合成很少使用，这正是本项目的内容。应制备组成为[M1 xM 21-x（NCS）2（L1）2]n和[M1 xM 21-x（NCS）2（L2）]n（M1、M2 = Mn（II）、Fe（II）、Co（II）和Ni（II）; L1 =单齿N-给体配体; L2 =桥接N-给体）的混晶，并研究其组成、均匀性和磁性。初步研究表明，从溶液中不能获得所需化合物的均匀样品。因此，使用了一种替代的合成路线，这是以前从未用于合成配位化合物的混合晶体。该策略基于合成组成为[M1 M21-x（NCS）2（L1）4]n和[M1 xM 21-x（NCS）2（L2）2]n的前体，其最终通过热分解转化为所需化合物。第一个结果表明，用这种方法可以制备由Co和Ni组成的均匀混合晶体，其表现出与合成中使用的组成完全对应的组成。加热时，它们定量地转变成所需的化合物。如磁性测量所示，在热分解时没有发生相分离，因为这些样品显示出与均三嗪化合物完全不同的磁性行为。在本文中，注意到[Co（NCS）2（吡啶）2]n表现出铁磁基态并显示出磁化的缓慢弛豫，而[Ni（NCS）2（吡啶）2]n表现出反铁磁基态并显示出变磁转变。与此相反，混合晶体的组合物[Co0.5Ni0.5（NCS）2（吡啶）2]n显示变磁过渡，这是典型的纯镍化合物，但在反铁磁相缓慢弛豫观察，这是典型的纯钴化合物。在该项目的过程中，应该研究这种合成工具是否可以普遍用于合成这类化合物的混合晶体，以及在混合晶体形成时发生的磁性变化。

项目成果

Synthesis and Magnetic Properties of the Layered Compound [Fe(NCS)2(4-acetylpyridine)2]n and Its Mixed Crystals with the Ni(II) Analogue

• DOI: 10.1021/acs.cgd.9b01657
• 发表时间: 2020-02
• 期刊: Crystal Growth & Design
• 影响因子: 3.8
• 作者: C. Wellm;M. Rams;Magdalena Ceglarska;C. Näther

Synthesis and Magnetic Properties of Solid Solutions of Ferromagnetic Layered Coordination Polymers Prepared from Solution and the Solid State

• DOI: 10.1021/acs.cgd.8b00865
• 发表时间: 2018-09
• 期刊: Crystal Growth & Design
• 影响因子: 3.8
• 作者: Tristan Neumann;M. Rams;C. Wellm;C. Näther

Tuning of the Critical Temperature in Magnetic 2D Coordination Polymers by Mixed Crystal Formation

通过混合晶体形成调节磁性二维配位聚合物的临界温度

• DOI: 10.1021/acs.cgd.8b00245
• 发表时间: 2018
• 期刊: Crystal Growth & Design
• 影响因子: 3.8
• 作者: Carsten Wellm;Michał Rams;Tristan Neumann;Magdalena Ceglarska;Christian Näther
• 通讯作者: Christian Näther