Alkali chalkogenido metalates(II/III)

混价硫属(Q)高铁酸盐(II/III)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，也是氧化还原酶或铁基超导体等复杂体系的模型。它们的晶体化学最近被许多混价富铁盐(主要通过还原合成策略)扩展了，它是基于边共享[FeQ4]四面体的。特别是A[FeQ2]-A2[FeQ2]截面上的四面体连接和阴离子/晶体结构：一方面，发现了几种构象中的边共享四面体链，这取决于Fe(II)：Fe(III)的比例和A离子。另一方面，[仅在混价高铁酸盐中]4Fe4S模拟四面体簇合物[Fe4Q8]作为特征构建块出现。通常，高铁酸盐(II/III)是Robin&Day III类的混价化合物，其磁性由HS-Fe(2/3)+-离子的强烈反铁磁耦合决定。然而，与纯高铁酸盐(II)和(III)的磁矩[类似于那些在纯高铁酸盐(II)和(III)]中的磁矩相比，相对于预期的‘仅自旋’值有相当大的降低，特别是在凝聚的多阴离子中。此外，新的钠盐Na7[Fe2S6]中的二聚体是一个非常罕见的例子，它的电荷波动导致了两个铁离子之间的铁磁耦合。基于这些结构和磁性不同的混价高铁酸盐(II/III)盐，本项目的目的是合成具有两种不同阳离子M2+(Mn，Co，Zn)和M3+(Al，In)的新的碱金属硫化物(II/III)，以确定它们的晶体结构和测量它们的磁性。对于新得到的(和相关的)化合物，用自旋极化的FP-LAPW DFT能带结构方法计算了化学键。对于这些含有异双金属多阴离子的盐的研究，M(II)：M(III)比高铁酸盐更容易调节，不仅允许模拟高铁酸盐(II/III)：首次对该结构家族的混合锰酸盐/高铁酸盐的结果表明，A[MQ2]-A2[MQ2]截面的晶体化学通过[MQ4]四面体的组合边/角和纯的边共享而得到显著扩展。这种结构的多样性以及金属阳离子本身的变化(如d电子数、磁性稀释、离子半径、M-Q键特性)导致了广泛的化学键和物理性质的变化。研究这些含低(Er)维金属酸盐(II/III)阴离子的碱性盐，并与高铁酸盐和纯金属盐(II)和(III)进行比较，可以提高对更复杂的混合价体系中成键和磁性的一般理解，例如上面提到的那些。

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.