Direct Visualization of Organometallic Intermediates on Cu(111) with Bond-Resolving Non-Contact Atomic Force Microscopy

In this study, we investigated the surface-confined coupling reactions of 1,8-dibromobiphenylene (BPBr₂) on Cu(111) to elucidate the details of the organometallic intermediates via Ullmann reactions. We used scanning tunneling microscopy (STM) to characterize the resulting organometallic intermediates. Moreover, submolecular resolution of the non-contact atomic force microscopy (nc-AFM) qPlus technique enables the bond-resolving within the organometallic dimer product. Our findings reveal the debromination of BPBr₂ on Cu(111), leading to the formation of an organometallic dimer intermediate at room temperature. Through nc-AFM measurements, we confirm and visualize the formation of the C-Cu-C bond. These insights enhance our understanding of Ullmann reaction and hold potential implications for the design of novel two-dimensional electronic devices.