Mono- and Di-Gold(I) Naphthalenes and Pyrenes: Syntheses, Crystal Structures, and Photophysics

(Phosphine)- and (N-heterocyclic carbene)gold(I) derivatives of naphthalene and pyrene are reported, containing one or two gold atoms per hydrocarbon. The new complexes are prepared by arylation of gold(I) substrates by arylboronic acids or aryl pinacolboronate esters in the presence of cesium carbonate. Isolated yields range from 52% to 98%. The boron precursors themselves derive from the parent hydrocarbon, where boron is installed in an iridium-catalyzed reaction, or from the aromatic bromides, which are borylated with palladium catalysis. Most of the new gold(I) complexes are air- and moisture-stable colorless solids; they are characterized by multinuclear NMR and optical spectroscopy, combustion analysis, and high-resolution mass spectrometry. X-ray diffraction crystal structures are reported for seven. Gold binding red-shifts optical absorption profiles, which are characteristic of the aromatic skeleton. All compounds show triplet-state luminescence, and dual singlet and triplet emission occurs in some instances. Phosphorescence persists for milliseconds at 77 K and for hundreds of microseconds at room temperature. The compounds’ photophysical characteristics, along with time-dependent density-functional theory calculations, suggest emission from ππ* states of the aromatic core. Triplet-state geometry optimization finds minimal geometric rearrangement upon one-electron promotion from the (singlet) ground state.

本研究报道了萘与芘的膦（Phosphine）基与氮杂环卡宾（N-heterocyclic carbene）基一价金衍生物，每个烃类骨架上连接1个或2个金原子。该类新型配合物可通过芳基硼酸或频哪醇芳基硼酸酯对一价金底物进行芳基化反应制备，反应体系需以碳酸铯为碱。分离产率介于52%至98%之间。硼基前驱体可通过两种途径制备：一是从母体烃类骨架出发，经铱催化反应引入硼原子；二是从芳基溴化物出发，经钯催化硼化反应得到。多数新型一价金配合物为对空气与水汽稳定的无色固体，通过多核核磁共振（multinuclear NMR）、光学光谱、燃烧分析以及高分辨质谱（high-resolution mass spectrometry）进行表征。已有7个配合物的X射线衍射晶体结构被报道。金原子的结合会使对应芳香骨架特征的光吸收谱发生红移。所有化合物均表现出三重态发光，部分化合物还可同时产生单重态与三重态发射。该类化合物的磷光在77 K下可持续数毫秒，在室温下可持续数百微秒。化合物的光物理特性结合含时密度泛函理论（time-dependent density-functional theory）计算结果表明，其发射源于芳香核的ππ*电子态。三重态几何构型优化结果显示，从（单重态）基态经单电子激发后，配合物的几何构型仅发生极小程度的重排。