Preparation and characterization of a series of rodlike binuclear ruthenium polyynediyl complexes capped with redox-active organometallic fragments [(bph)(PPh3)(2)Ru](+) (bph = N-(benzoyl)-N'-(picolinylidene)-hydrazine) or [(Phtpy)(PPh3)(2)Ru](2+) (Phtpy = 4'-phenyl-2,2':6',2' '-terpyridine) have been carried out. The length of the molecular rods is extended by successive insertion of 2,5-thiophene or 1,4-phenylene spacers in the bridging ligands. Oxidation of thiophene-containing Ru-2(II,II) complexes induces isolation of stable Ru-2(II,III) or Ru-2(III,III) species. Electrochemical and UV-vis-NIR spectral studies demonstrate that the polyynediyl bridges with 2,5-thiophene units are more favorable for metal-metal charge transfer compared with those containing the same number of 1,4-phenylene units. Successive increase of thiophene spacers in mixed-valence complexes {Ru-II}-CC(C4H2S)(m)CC-{Ru-III} (m = 1, 2, 3) induced a smooth transition from almost electronic delocalization (m = 1) to localization (m = 3). For binuclear ruthenium complexes with intramolecular electron transfer transmitted across nine Ru-C and C-C bonds, electronic conveying capability follows {Ru}-CC(CC)(2)CC-{Ru} > {Ru}-CC(C4H2S)CC-{Ru} > {Ru}-CC(C6H4)CC-{Ru} > {Ru}-CC(CHCH)(2)CC-{Ru}. It is revealed that molecular wires capped with electron-rich (bph)(PPh3)(2)Ru endgroups are much more favorable for electronic communication than the corresponding electron-deficient (Phtpy)(PPh3)(2)Ru-containing counterparts. The intermetallic electronic communication is fine-tuned by modification of both the bridging spacers and the ancillary ligands.