Recently, we reported the first metal-bridged tricyclic aromatic system. This research has been published on Angew. Chem. Int. Ed. (2014, 53, 6181) entitled “A Metal-Bridged Tricyclic Aromatic System: Synthesis of Osmium Polycyclic Aromatic Complexes”.

    Aromaticity is one of the most important concepts in organic chemistry. Recently, a variety of metalla-aromatics have been prepared and in most of those examples the metal only participates in a monocyclic ring. By contrast, metal-bridged bicyclic aromatics, in which a metal is shared by two aromatic rings, have been less developed. Here, we report the first metal-bridged tricyclic aromatic system, in which the metal center is shared by three aromatic five-membered rings. These metalla-aromatics are formed by reactions of osmapentalyne with arene nucleophiles. Experimental results and theoretical calculations reveal that the three five-membered rings around the osmium center are aromatic. In addition, the broad absorption bands in the UV-vis absorption spectra of these novel aromatics cover almost the entire visible region. The straightforward synthetic strategy described here could be extended to the synthesis of other metal-bridged polycyclic aromatics.

    The research was supported by the National Basic Research Program of China, the National Science Foundation of China and the Program for New Century Excellent Talents in University.

    URL link for article: http://onlinelibrary.wiley.com/doi/10.1002/anie.201403245/abstract