Iterative Synthesis of Oligoynes Capped by a Ru2(ap)4-terminus and Their Electrochemical and Optoelectronic Properties

Cross-coupling reactions between terminal ethynes (HC⋮CY) and Ru 2 ( ap ) 4 (C 2( k - 1) H) under Hay conditions, where ap is 2-anilinopyridinate and k = 2−5, resulted in compounds Ru 2 ( ap ) 4 (C 2k Y) (Y = Si i Pr 3 and Ph) along with the homocoupling products YC 4 Y and [Ru 2 ( ap ) 4 ] 2 (μ-C 4( k - 1) ). Compounds Ru 2 ( ap ) 4 (C 2 k Y) display two reversible Ru 2 -based one-electron couples: an oxidation and a reduction. The HOMO−LUMO gaps ( E g ) estimated from electrode potentials correlate linearly with the number of acetylenic bonds ( k ) within each series. Both nonlinear absorption and degenerate four-wave mixing measurements were carried out at both 532 and 800 nm with nano- and femtosecond laser pulses.