Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, UK.
Department of Chemistry, Durham University, Lower Mountjoy, South Road, Durham DH1 3LE, UK.
Nat Chem. 2017 Jul;9(7):644-652. doi: 10.1038/nchem.2765. Epub 2017 Apr 24.
Alkali metal intercalation into polyaromatic hydrocarbons (PAHs) has been studied intensely after reports of superconductivity in a number of potassium- and rubidium-intercalated materials. There are, however, no reported crystal structures to inform our understanding of the chemistry and physics because of the complex reactivity of PAHs with strong reducing agents at high temperature. Here we present the synthesis of crystalline KPentacene and KPicene by a solid-solid insertion protocol that uses potassium hydride as a redox-controlled reducing agent to access the PAH dianions, and so enables the determination of their crystal structures. In both cases, the inserted cations expand the parent herringbone packings by reorienting the molecular anions to create multiple potassium sites within initially dense molecular layers, and thus interact with the PAH anion π systems. The synthetic and crystal chemistry of alkali metal intercalation into PAHs differs from that into fullerenes and graphite, in which the cation sites are pre-defined by the host structure.
碱金属嵌入多环芳烃（PAHs）的研究在报道了一些钾和铷嵌入材料的超导性后变得非常活跃。然而，由于 PAHs 在高温下与强还原剂的复杂反应性，目前还没有报道的晶体结构来帮助我们理解其化学和物理性质。在这里，我们提出了一种使用氢化钾作为氧化还原控制还原剂的固-固插入法来合成结晶 KPentacene 和 KPicene，从而可以获得 PAH 二阴离子，并确定它们的晶体结构。在这两种情况下，插入的阳离子通过重新排列分子阴离子来扩展母体鱼骨状堆积，从而在最初密集的分子层内创建多个钾位，从而与 PAH 阴离子π系统相互作用。碱金属嵌入 PAHs 的合成和晶体化学与嵌入富勒烯和石墨的合成和晶体化学不同，在后者中，阳离子位由主体结构预先确定。
