SYNTHESIS AND SPECTROELECTROCHEMICAL CHARACTERIZATION OF BINUCLEAR COMPLEXES OF BIS(BIPYRIDINE) RUTHENIUM AND PENTAAMMINERUTHENIUM BRIDGED WITH ALPHA,OMEGA-DIPYRIDYLCYANINES

As part of our systematic investigation of solitonic behavior in molec ules and search for structural and dimensional requirements for molecu lar level electronic components, we have prepared two binuclear compou nds which incorporate a pyridocyanine bridging segment between two rut henium complexes. [(NH3)(5)Ru(LH)Ru(NH3)(5)](PF6)(4) and [(bipy)(2)ClR u(LH)RuCl(bipy)(2)](PF6)(2) (where LH is 1,5-dipyridyl-1,3-pentadiene) and the mononuclear complexes [(NH3)(5)Ru(LH)](PF6)(2) and [Ru(bipy)( 2)(LH)Cl](PF6) were synthesized by ligand substitution from the conven ient precursors Ru(bipy)(2)Cl-2 and [Ru(NH3)(5)Cl]Cl-2. Deprotonation of the dimeric complexes M-LH-M afforded cyanine-linked complexes M-L- M. Attempts to prepare mixed-valence polyenyl complexes electrooxidati vely were unsuccessful. A spectroelectrochemical investigation reveale d that oxidation of the deprotonated polyenyl bridging moiety occurred at a lower potential than that required for oxidation of the termini centers in the deprotonated complex [(bipy)(2)ClRu(L)RuCl(bipy)(2)](PF 6)(2). Similarly, the expected intervalence transfer between the polye ne terminal groups in deprotonated [(NH3)(5)Ru(L)Ru(NH3)(5)](PF6)(4) w as not realized due to ligand dissociation.