Surface-Assisted Formation, Assembly, and Dynamics of Planar Organometallic Macrocycles and Zigzag Shaped Polymer Chains with C-Cu-C Bonds

The formation, structure, and dynamics of planar organometallic macrocycles (meta-terphenyl-Cu)(n) and zigzag-shaped one-dimensional organometallic polymers on a Cu(111) surface were studied with scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). Vapor deposition of 4,4 ''-dibromo-meta-terphenyl (DMTP) onto Cu(111) at 300 K leads to C-Br bond scission and formation of C-Cu-C bonds, which connect neighboring meta-terphenyl fragments such that room-temperature stable macrocycles and zigzag chains are formed. The chains self-assemble to form islands, which are elongated in the direction of the chains. If DMTP is deposited onto Cu(111) held at 440 K, the island size is drastically increased (>200 x 200 nm(2)). STM sequences show the formation of ordered structures through reversible scission and reformation of the C-Cu-C bonds. The cyclic organometallic species such as the hexamer (meta-terphenyl-Cu)(6) may represent intermediates in the surface-confined Ullmann synthesis of hydrocarbon macrocycles such as the recently discovered hyperbenzene.