Four heterodimetallic complexes [Ru(Fcdpb)(L)](PF6) (Fcdpb=2-deprotonated form of 1,3-di(2-pyridyl)-5-ferrocenylbenzene; L=2,6-bis-( N-methylbenzimidazolyl)-pyridine (Mebip), 2,2′:6′,2′′-terpyridine (tpy), 4-nitro-2,2′:6′,2′′-terpyridine (NO2tpy), and trimethyl-4,4′,4′′-tricarboxylate-2,2′:6′,2′′-terpyridine (Me3tctpy)) have been prepared. The electrochemical and spectroelectrochemical properties of these complexes have been examined in CH2Cl2, CH3NO2, CH3CN, and acetone. These complexes display two consecutive redox couples owing to the stepwise oxidation of the ferrocene (Fc) and ruthenium units, respectively. The potential difference, Δ E1/2 ( E1/2(RuII/III)− E1/2(Fc0/+)), decreased slightly with increasing solvent donocity. The mixed-valent states of these complexes have been generated by and the resulting intervalence charge-transfer (IVCT) bands have been analyzed by Hush theory. Good linear relationships exist between the energy of the IVCT band, Eop, and Δ E1/2 of four mixed-valent complexes in a given solvent. [ABSTRACT FROM AUTHOR]