Modulating the Framework Negative Charge Density in the System [BDT−TTP•+]/[Re6S5Cl91-]/[Re6(S/Se)6Cl82-]/[Re6S7Cl73-]: Templating by Isosteric Cluster Anions of Identical Symmetry and Shape, Variations of Incommensurate Band Filling, and Electronic Structure in 2D Metals

A series of 2D metals, β-(BDT-TTP)6[Re6Se6Cl8]·(CHCl2−CHCl2)2, 2; β-(ST-TTP)6[Re6S6Cl8]·(CH2Cl−CHCl2)2, 3; β-(BDT-TTP)7[Re6S6Cl8]0.5[Re6S7Cl7]0.5·(CH2Cl2), 4; β-(BDT-TTP)7[Re6Se6Cl8]0.5[Re6S7Cl7]0.5·(CH2Cl2), 5; β-(BDT-TTP)8[Re6S7Cl7]·(CH2Cl2)4, 6 (BDT-TTP and ST-TTP are 2,5-bis(1,3-dithiol-2-ylidene)-1,3,4,6-tetrathiapentalene and 2-(1,3-diselenol-2-ylidene)-5(1,3-dithiol-2-ylidene)-1,3,4,6-tetrathiapentalene, respectively) is reported to have one single β-slab layered topology despite successive
increases of the cluster anion negative charge. The charge density within the templating composite
inorganic−neutral molecule slab is shown to remain above a threshold of ca. one negative charge per
square nanometer, that is, for cluster anions with two negative charges and higher. Conversely, discrete
stacks are shown to be stabilized instead in the semiconducting salts (BDT-TTP)2[Re6S5Cl9], 1 where the
cluster anion bears one negative charge only. The electronic structure of salts 2−6 is shown to be very
stable and kept almost intact across the series. The templating strategy is shown to fulfill its anticipated
potential for deliberate installment of incommensurate band fillings in molecular metals. The deliberate
admixture of the 6:1 and 8:1 structures yields novel phases with a 7:1 stoichiometry with the anticipated
crystal and electronic structures. The action at the organic−inorganic interface triggered by changing the
anion charge yet keeping its shape and volume identical, which ultimately governs the shape of the unit
cell, is of paramount importance in defining the Fermi surface of these metallic salts. The present BDT-TTP salts thus provide a series of materials with strongly related but subtly different Fermi surfaces worthy
of many physical studies. Shubnikov−de Haas measurements are expected to be particularly interesting
since they are especially sensitive to the details of the Fermi surface.

一系列二维金属化合物，包括β-(BDT-TTP)6[Re6Se6Cl8]·(CHCl2−CHCl2)2, 2；β-(ST-TTP)6[Re6S6Cl8]·(CH2Cl−CHCl2)2, 3；β-(BDT-TTP)7[Re6S6Cl8]0.5[Re6S7Cl7]0.5·(CH2Cl2), 4；β-(BDT-TTP)7[Re6Se6Cl8]0.5[Re6S7Cl7]0.5·(CH2Cl2), 5；β-(BDT-TTP)8[Re6S7Cl7]·(CH2Cl2)4, 6（其中BDT-TTP和ST-TTP分别指2,5-双(1,3-二硫代亚甲基)-1,3,4,6-四硫五氮杂环戊烯和2-(1,3-二硒醇-2-亚甲基)-5(1,3-二硫代亚甲基)-1,3,4,6-四硫五氮杂环戊烯），尽管簇阴离子负电荷依次增加，但报告显示这些化合物仍保持单一的β-板层拓扑结构。在模板复合无机-中性分子板中，电荷密度被证实维持在约每平方纳米一个负电荷的阈值以上，即对于具有两个或更多负电荷的簇阴离子而言。相反，离散的堆叠在半导体盐（BDT-TTP）2[Re6S5Cl9], 1中得到稳定，其中簇阴离子仅带有一个负电荷。盐类2-6的电子结构显示出极高的稳定性，并在整个系列中保持几乎完好无损。模板策略被证明能够实现其预期的潜力，即在分子金属中故意引入非公度能带填充。6:1和8:1结构的故意混合产生了具有7:1化学计量比的全新相，并具有预期的晶体和电子结构。在保持阴离子形状和体积不变的同时改变其电荷，从而引发的有机-无机界面作用，对于最终决定单位晶胞形状，并在定义这些金属盐的费米面方面具有至关重要的意义。因此，当前的BDT-TTP盐提供了一系列具有紧密相关但细微差异的费米面，值得进行大量物理研究。预计Shubnikov−de Haas测量将特别有趣，因为它们对费米面的细节特别敏感。