Reactivity of Solid Rubrene with Potassium: Competition between Intercalation and Molecular Decomposition.
Reactivity of Solid Rubrene with Potassium: Competition between Intercalation and Molecular Decomposition.
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DOI：
10.1021/jacs.8b11231
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发表时间：
2018-11
影响因子：
15
通讯作者：
Jiliang Zhang;G. Whitehead;T. Manning;D. Stewart;C. I. Hiley;M. J. Pitcher;S. Jansat;K. Prassides;M. Rosseinsky
中科院分区：
文献类型：
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作者：
Jiliang Zhang;G. Whitehead;T. Manning;D. Stewart;C. I. Hiley;M. J. Pitcher;S. Jansat;K. Prassides;M. Rosseinsky
我们提出了K+插层rubrene （C42H28）相K2Rubrene （K2R）的合成和表征，并在结晶成分为相纯的样品中鉴定了非晶和结晶材料的共存。我们认为这是许多插层碱金属-多芳烃（PAH）体系的特征，包括那些声称具有超导性的体系。利用K和KH源对K-rubrene固相反应的系统研究表明，K插层与rubrene的分解之间存在复杂的竞争关系，产生了三种K插层化合物，即K2R、K（RR*）和K xR‘（其中R*和R’分别是rubrene分解衍生物C42H26和C30H20）。K2R是在很宽的组成范围内获得的主要相，并伴随着由rubrene分解形成的无定形副产物。K（RR*）作为单相合成，而K xR'仅作为次要相获得。利用高分辨率粉末x射线衍射测定了K2R的晶体结构，揭示了原始rubrene的结构重排在每个rubrene的分子层中产生了两个大的空隙，其中K+被纳入其中。在大孔洞内的K+阳离子通过η6、η3和η2结合模式与相邻的rubrene发生强烈的相互作用，并与四烯核和苯基结合。这与其他嵌入的多环芳烃形成对比，其中每个多环芳烃只产生一个空洞，并且嵌入的K+与宿主的相互作用弱。rubrene的分解产物也使用溶液核磁共振检查，突出了c -苯基键断裂的作用。对于晶体分解衍生产物K（RR*）和K xR‘，由于缺乏关于R*和R’的明确结构信息，导致无法确定晶体结构。这项研究说明了获取无溶剂的碱金属盐的复杂性减少多环芳烃的类型声称提供超导性。
We present the synthesis and characterization of the K+-intercalated rubrene (C42H28) phase, K2Rubrene (K2R), and identify the coexistence of amorphous and crystalline materials in samples where the crystalline component is phase-pure. We suggest this is characteristic of many intercalated alkali metal-polyaromatic hydrocarbon (PAH) systems, including those for which superconductivity has been claimed. The systematic investigation of K-rubrene solid-state reactions using both K and KH sources reveals a complex competition between K intercalation and the decomposition of rubrene, producing three K-intercalated compounds, namely, K2R, K(RR*), and K xR' (where R* and R' are rubrene decomposition derivatives C42H26 and C30H20, respectively). K2R is obtained as the major phase over a wide composition range and is accompanied by the formation of amorphous byproducts from the decomposition of rubrene. K(RR*) is synthesized as a single phase, and K xR' is obtained only as a secondary phase to the majority K2R phase. The crystal structure of K2R was determined using high-resolution powder X-ray diffraction, revealing that the structural rearrangement from pristine rubrene creates two large voids per rubrene within the molecular layers in which K+ is incorporated. K+ cations accommodated within the large voids interact strongly with the neighboring rubrene via η6, η3, and η2 binding modes to the tetracene cores and the phenyl groups. This contrasts with other intercalated PAHs, where only a single void per PAH is created and the intercalated K+ weakly interacts with the host. The decomposition products of rubrene are also examined using solution NMR, highlighting the role of the breaking of C-Cphenyl bonds. For the crystalline decomposition derivative products K(RR*) and K xR', a lack of definitive structural information with regard to R* and R' prevents the crystal structures from being determined. The study illustrates the complexity in accessing solvent-free alkali metal salts of reduced PAH of the type claimed to afford superconductivity.