Alkali chalkogenido metalates(II/III)

碱金属硫族金属酸盐(II/III)

• 批准号: 313431712
• 负责人: Professorin Dr.-Ing. Caroline Röhr
• 金额: --
• 依托单位: Lehrstuhl für Festkörperchemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/313431712?language=en
• 关键词: Alkali; chalkogenido; metalates; II; III

Alkali metal (A) salts of mixed-valent chalcogenido(Q) ferrate(II/III) anions (A=Na, K, Rb Cs; Q=S, Se, Te) are a structurally variable class of compounds, which are furthermore models for much complexer systems like e.g. redox enzymes or iron-based superconductors.Their crystal chemistry, which has been recentyl extended by many mixed-valent Fe-rich salts (mainly via using reductive synthetic strategies) is based on edge-sharing [FeQ4] tetrahedra. Particularly diverse are the tetrahedra connections and the anions/crystal structures along the section A[FeQ2]-A2[FeQ2]: At one hand, chains of edge-sharing tetrahedra in several conformations, which depend on the Fe(II):Fe(III) ratio and the A cations, are found. On the other hand [exclusively in mixed-valent ferrates] 4Fe4S analog tetrahedra clusters [Fe4Q8] occur as characteristic building blocks. Commonly, the ferrates(II/III) are mixed-valent compounds of Robin&Day class III, with magnetic properties determined by a strong antiferromagnetic coupling of the HS-Fe(2/3)+- ions. However, the magnetic moments [similar to those in pure ferrates(II) and (III)] are considerably decreased with respect to the expected 'spin-only' values, especially in the condensed polyanions. Additionally, the dimer in the new sodium salt Na7[Fe2S6] is one of the very rare examples, for which charge fluctuations result in a ferromagnetic coupling between the two Fe ions.Based on these structurally and magnectically diverse mixed-valent ferrate(II/III) salts, the aim of this project is to synthesize new alkali chalcogenido metallates(II/III) with two different cations M2+ (Mn, Co, Zn) and M3+ (Al, In), to determine their crystal structures and to measure their magnetic properties. For the newly obtained (and related) compounds, the chemical bonding is calculated using spin-polarized FP-LAPW DFT band structure methods.The investigation of these salts containing heterobimetallic polyanions, for which the ratio M(II):M(III) can be ajusted much easier than for the ferrates, does not only allow to mimic the ferrates(II/III): First results on mixed manganates/indates of this structure family show, that the crystal chemistry along the section A[MQ2]-A2[MQ2] is considerably extended by acombined edge/corner and a pure edges-sharing of [MQ4] tetrahedra. This structure diversity as well as the variation of the metal cations themselves (e.g. number of d electrons, magnetic dilution, ionic radii, M-Q bond character) results in a wide range of the chemical bonding and the physical properties. The investigation of these basic alkali salts with low(er)-dimensional metallate(II/III) anions and the comparison with the ferrates and the pure metallates(II) and (III), allows to improve the general understanding of the bonding and the magnetism also in much complexer mixed-valent systems, e.g. like those mentioned above.

混合价硫属（Q）高铁酸盐（II/III）阴离子的碱金属（A）盐（A=Na，K，Rb，Cs; Q=S，Se，Te）是一类结构可变的化合物，它们也是更复杂系统的模型，例如氧化还原酶或铁基超导体。其已经被许多混合价富铁盐（主要通过使用还原合成策略）进行了新戊基扩展，是基于共享边的[FeQ 4]四面体。特别不同的是四面体连接和沿着截面A[FeQ 2]-A2[FeQ 2]的阴离子/晶体结构：一方面，发现了几种构象的共边四面体链，这取决于Fe（II）：Fe（III）的比例和A阳离子;另一方面[仅在混合价高铁酸盐中] 4Fe 4S类似四面体簇[Fe 4 Q 8]作为特征性的构建块出现。通常，高铁酸盐（II/III）是Robin&Day III类的混合价化合物，其磁性由HS-Fe（2/3）+-离子的强反铁磁耦合决定。然而，磁矩[类似于纯高铁酸盐（II）和（III）中的磁矩]相对于预期的“仅自旋”值显著降低，特别是在凝聚的聚阴离子中。另外，新型钠盐Na 7 [Fe 2S 6]中的二聚体是一个非常罕见的例子，其电荷波动导致两个Fe离子之间的铁磁耦合，基于这些结构和磁性不同的混合价高铁酸盐（II/III），本项目的目标是合成具有两个不同阳离子M2+的新型碱金属硫属金属（II/III）盐（Mn，Co，Zn）和M ~（3+）（Al，In）的晶体结构和磁性能。 对于新获得的对这些含有杂多阴离子的盐的研究，其中M（II）：M（III）的比例可以比高铁酸盐容易得多地调整，不仅允许模拟高铁酸盐（II/III）：对这种结构族的混合锰酸盐/铟酸盐的第一个结果显示，沿着截面A[MQ 2]-A2[MQ 2]的晶体化学沿着通过[MQ 4]四面体的结合边/角和纯边共享而显著扩展。这种结构多样性以及金属阳离子本身的变化（例如d电子数、磁稀释、离子半径、M-Q键特征）导致宽范围的化学键合和物理性质。这些基本的碱金属盐与低（er）维金属（II/III）阴离子的调查和与高铁酸盐和纯金属（II）和（III）的比较，允许提高键合和磁性的一般理解，也在更复杂的混合价系，例如像上面提到的那些。