Modifications of diruthenium molecular wires through ancillary ligand exchange

AEI 58

Sarah L. Bolton and Michael B. Sponsler, sponsler@syr.edu. Department of Chemistry, Syracuse University, Syracuse, NY 13244-4100
New diruthenium complexes have been synthesized using olefin metathesis for metal incorporation (OMMI) and subsequent ligand exchange. The parent complexes were prepared using two equivalents of a ruthenium catalyst and one equivalent of 1,3,5,7-octatetraene. Ancillary ligand exchange was then used to extend this family of compounds. The 3-bromopyridine analogs of Grubbs first and second generation benzylidene catalysts were stabilized by tributylphosphine; this strategy was also utilized for the diruthenium complex. The tributylphosphine substitution significantly increased stability and reduced the metathesis activity. The redox activity of the complexes was studied using cyclic voltammetry and differential pulse voltammetry. Substitution of the labile 3-bromopyridine ligands, of the diruthenium complexes and the precursor catalysts, with pyrazine was used to synthesize aurophilic complexes to determine the single molecule electronic properties of the bridged species.