The trimetallic, mixed-valence complex [(NC)(5)Fe-II-CN -Pt-IV(NH3)(4)-NC-Fe-II(CN)(5)](4-) was surface-attached to colloidal TiO2. The system was characterized by UV/vis absorption, diffuse reflectance IR, and resonance Raman spectroscopies. The surface-bound complex absorbed at 400 nm, corresponding to Fe(II)--> Pt(IV) intervalent electron transfer. Exhaustive irradiation into this band resulted in a broadening of the visible absorption band and a change in the bridging cyanide stretching bands of the resonance Raman spectrum. The distribution of bridging cyanide Raman intensities in the exhaustively irradiated sample was found to vary with incident wavelength. The UV/vis absorption and resonance Raman spectral changes are explained in terms of a rearrangement of the surface-binding geometry of the complex, resulting in the selectivity of electron-transfer direction within the complex. Irradiation of Fe(CN)(6)(3-) in the presence of TiO2 with visible light resulted in the photoreduction of Fe(CN)63- to Fe(CN)63-. This photoreduction is believed to occur by direct TiO2(VB) --> Fe(t(2g)) photoinduced electron transfer, rather than electron transfer from photoexcited TiO2 to Fe(CN)(6)(3-).