We report the synthesis and characterization of 14 complexes of the general form [CpRu(oligothiophene)]PF6 and [Cp*Ru(oligothiophene)]PF6 (Cp = eta(5)-cyclopentadienyl; Cp* = eta(5)-pentamethylcyclopentadienyl). The complexes were synthesized from [CpRu(CH3CN)(3)]PF6 or [Cp*Ru(CH3CN)(3)]PF6 and the appropriate oligothiophene via procedures previously reported for other [Cp/Cp*Ru(eta(6)-arene)]PF6 sandwich complexes. For the oligothiophenes 2,2’-bithiophene (Bth), 2,2’:5’,2 "-terthiophene (Tth), 2,2’:5’,2 ":5 ",2"’-quaterthiophene (Qth), and 5,5 "-dimethyl-2,2’:5’,2 "-terthiophene (Me(2)Tth), the Ru is bound eta(5) to the outermost thiophene ring while the complexes of the oligothiophene 5,5 "-diphenyl-2,2’:5’,2 "-terthiophene (Ph(2)Tth) have Ru bound eta(6) to a pendant phenyl group. The complexes with ruthenium bound to an arene are very stable with respect to decomplexation; complexes with ruthenium bound to a thiophene ring art stable in the solid state and in dichloromethane solutions; in acetone, rearrangement reactions occur to produce equilibrium mixtures of free oligothiophene and mono- and diruthenated species. Detailed analysis of H-1 and C-13 NMR spectra, H-1-H-1 decoupling experiments. heteronuclear multiple-bond correlation (HMBC), and heteronuclear multiple-quantum coherence (HMQC) experiments enabled the assignment of all H-1 and C-13 resonances. These assignments show that binding ruthenium to a thiophene ring of an oligothiophene shifts the bound ring resonances upfield and the unbound thiophene rings downfield. The coordination of ruthenium exerts a larger electronic effect in oligothiophene complexes than in polyaromatic complexes (quaterphenyl). Complexation of a thiophene ring by ruthenium will affect the electronic structure of up to five thiophene rings : the bound ring and the next two unbound thiophene rings on either side.