Two new structurally diverse Polyazine-bridged tetrametallic complexes; [{(Ph(2)phen)(2)Ru- (dpp)}(2)Ru(dpp)PtCl2(PF6)(6) (1a) and 1{(Ph(2)phen)(2)Ru- (dpp)}(2)Ru(dpq)PtCl2(PF6)(6) (2a) (Ph(2)phen = 4,7-diphenyl-1,10-phenanthroline, dpp = 2,3-bis(2-pyridyl)pyrazine, dpq 2,3-bis(2-pyridyl)quinoxaline), as well as their trimetallic precursors have been synthesized to provide a comparison for analysis to elucidate component effects in the previously reported., photocatalyst [{(phen)2Ru(dpp)}(2)Ru-. (dpq)PtCl2](PF6)(6) (4a) (phen = 1,107phenanthroline) Electrochemistry shows terminal Ru based highest ocuipied molecular orbitals (HOMOs) with remote BL' (BL' = bridging ligand coupling central Ru and cis-PtCl2 moiety) based lowest, unoccupied molecular :orbitals (LUMOs). Population of a lowest lying charge' separated ((CS)-C-3) excited state with oxidizedZterininat.Ru and reduced BL' via intramolecular electron transfer is predicted by electrochemical analysis and is observed through.steady-state and time resolved emission studies as well as emission excitation profiles which display unusual nonunity population of lowest lying emissive Ru -> dpp (MLCT)-M-3 (metal-to-liganct charge transfer) state. Each.tetrametallic complex is an active photocatalyst for H2 production from H2O with 2a showing the highest 'activity (94 TON (turnover number) in 10 h, where TON = mol H2/mol catalyst). The nature of the bridging ligand coupling the trimetallic light absorber to the cis-PtCl2 moiety has a significant impact on the catalyst activity, Correlated to the degree of population of the (CS)-C-3 excited state. The choice of terminal ligand affects visible light absorption and a.minor influence on photocatalytic H-2 production from H2O. Evidence that an intact supramoleculc functions as the photOcatalyst includes a strong dependence of the photocatalysis on the identity of BL', an insensitivity to Hg(I), no detectable H-2 production from the systems with the inmetallic synthons and cis-[PtCl2(DMSO)(2)] as well as spectroscopic analysis of the.-.phiatoCatalytic system.