Template-Steered Transformation of Isocyanides to Cumulene-Containing Organometallic Polymers on Ag(110)

On-surface synthesis provides a powerful strategy for the atomically precise fabrication of low-dimensional nanoscale structures. However, controlling on-surface reaction pathways remains a challenge because of the irreversible and poorly selective nature of covalent coupling. Here, we report the direct transformation from isocyanides to cumulenes via the in situ formation of organometallic templates on Ag(110) and achieve the synthesis of two cumulene-containing organometallic polymers: chains (CC-OMCs) and networks (CC-OMNs). Using a bifunctional precursor 1,4-dibromo-2,5-diisocyanobenzene (DBDICB), the surface-assisted debromination performed the organometallic chain templates with heterotactic (hetero-OMCs) and homotactic (homo-OMCs) arrangement configurations between neighboring dehalogenated molecular units. The individual hetero-OMCs underwent intrachain polymerization to form the CC-OMCs. In contrast, increasing the coverage of DBDICB on Ag(110) drove the formation of 2D assembled structures of homo-OMCs by electrostatic interactions, thereby further promoting interchain polymerization to form CC-OMNs.