α-Diazo Ketones in On-Surface Chemistry

Polymerization of a biphenyl bis alpha-diazo ketone on Cu(111) and Au(111) surfaces to provide furandiyl bridged poly-para-phenylenes is reported. Polymerization on Cu(111) occurs via initial N-2 fragmentation leading to Cu-biscarbene complexes at room temperature as polymeric organometallic structure. At 135 degrees C, carbene coupling affords polymeric alpha,beta-unsaturated 1,4-diketones, while analogous alkene formation on the Au(111) surface occurs at room temperature. Further temperature increase leads to deoxygenative cyclization of the 1,4-diketone moieties to provide alternating furandiyl biphenyl copolymers on Cu(111) (165 degrees C) and Au(111) (240 degrees C) surfaces. This work shows a new approach to generate Cu-biscarbene intermediates on surfaces, opening the pathway for the controlled generation of biphenyl copolymers.