“Doping” of Polyyne with an Organometallic Fragment Leads to Highly Conductive Metallapolyyne Molecular Wire

Exploration of highly conductive molecules is essential to achieve single-molecule electronic devices. The present paper describes the results on single-molecule conductance study of polyyne wires doped with the organometallic Ru­(dppe)2 fragment, X(CC)nRu­(dppe)2(CC)nX. The metallapolyyne wires end-capped with the gold fragments (X = AuL) are subjected to single-molecule conductance measurements with the STM break junction technique, which reveal the high conductance (10–3–10–2 G0; n = 2–4) with the low attenuation factor (0.25 Å–1) and the low contact resistance (33 kΩ). A unique “‘doping’” effect of Ru­(dppe)2 fragment was found to lead to the high performance as suggested by the hybrid density functional theory-nonequilibrium green function calculation.