Cyanide-bridged trinuclear complexes containing square-planar platinum at the center were synthesized and identified by structure determinations. Their chemical building blocks were cis- and trans-PtL2X2, Cp(dppe)FeX, Cp(PPh3)(2)RuX (with X = Hal or CN), Pt(CN)(4)(2-), and Fe(CN)(6)(3-). Several of the intermediate dinuclear complexes were isolated and used for reference purposes; The molecular structures, the v(CN) IR data, the cyclic voltammograms, and the UV-vis-near-IR spectra were used to probe the effects of the geometry at platinum (cis vs trans), of cyanide-isocyanide isomerism (Pt(CN)(2) vs Pt(NC)(2)), of the nature and ligation of the terminal metals (Fe vs Ru), and of one- or two-electron oxidation. The redox properties and the observed intervalence transfers indicate that there is electronic communication between the outer metal atoms along the linear M-CN chains containing trans-configured platinum, but not along the bent chains containing cis configured platinum.