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

摘要

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 4,400-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 metaterphenyl 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 (>200×200 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.