The on-surface reaction processes of 1,4-dibromo-2,5-diiodobenzene (C₆H₂Br₂I₂) on Au(111) and Ag(100) were systematically investigated under ultra-high vacuum conditions by using scanning tunneling microscopy. Deiodination underwent at RT on both surfaces with the formation of organometallic intermediates connected by C–Au–C and C–Ag–C linkages. In particular, partial deiodination on Au(111) resulted in self-assembled ordered structures of organometallic trans-trimers, which were converted into longer organometallic chains after complete deiodination at 100 °C. On Ag(100), complete deiodination gave rise to disordered molecular clusters at RT and organometallic intermediates were formed via the debromination process after annealing to 150 °C. Further annealing to higher temperatures resulted in covalent C–C bonded polyphenylene chains and finally disordered graphene nanostructures via cyclodehydrogenation. Our study provides fundamental comprehension of temperature-selective on-surface dehalogenation reactions of multi-halogen-substituted precursors for constructing designer covalently bonded networks.

中文翻译：

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1,4-二溴-2,5-二碘苯在 Au(111) 和 Ag(100) 上的表面反应

_{1,4-二溴-2,5-二碘苯(C 6} H ₂ Br ₂ I ₂ )的表面反应过程) 在超高真空条件下使用扫描隧道显微镜系统地研究了 Au(111) 和 Ag(100)。两个表面在室温下进行脱碘，形成由 C-Au-C 和 C-Ag-C 键连接的有机金属中间体。特别是，Au(111) 上的部分脱碘导致有机金属反式三聚体的自组装有序结构，在 100 °C 下完全脱碘后转化为更长的有机金属链。在 Ag(100) 上，完全脱碘在室温下产生无序分子簇，并且在退火至 150 °C 后通过脱溴过程形成有机金属中间体。进一步退火到更高的温度导致共价 C-C 键合的聚亚苯基链，并最终通过环化脱氢形成无序的石墨烯纳米结构。