Linear trimers of diruthenium linked by polyyndiyl or phenylenediethynyl bridges: A family of unique electronic wires

Abstract

A new family of wire-like molecules with butadiyndiyl (1a/b), hexadiyndiyl (2) and phenylenediethynyl (3) bridges linking three diruthenium units have been prepared. The single crystal X-ray diffraction study of 1a revealed structural details of the trimeric compounds, including a distance of 18Å between two Ru2 termini. Both the voltammetric and spectroscopic data point to an extensive electronic delocalization in trimers 1 and 2, and the lack of delocalization in 3, demonstrating the advantage of linear polyyndiyl in mediating intermetallic electronic couplings. Magnetic studies of compound 1a reveal that a spin transition may occur as the temperature increases from 1.8 to 300K.