Electrochemical and infrared spectroscopic study of the self-assembled monolayer of a cyano-bridged dimeric triruthenium complex on gold surface

A new cyano-bridged dimeric oxo-centered triruthenium complex [{Ru3(μ3-O)(μ-CH3COO)6(py)2}(μ-CN){Ru3(μ3-O)(μ-CH3COO)6(py)(Lpy-SS)}]+ (py = pyridine, Lpy-SS = (C5H4N–CH2NHC(O)(CH2)4CH(CH2)2SS) ([1]+) has been prepared, characterized, and confined on an Au(1 1 1) surface to form self-assembled monolayers (SAMs) (1/Au). The redox and IR spectroscopic properties observed for the discrete ions are essentially preserved in its SAMs. The molecules of SAMs 1/Au stand up with the cyano groups tilted to the gold surface. The electronic structures of 1/Au in different oxidation states have been studied by in situ infrared spectroscopy monitoring the stretching modes of the cyano group. The extent of cyano-mediated electronic communications between two triruthenium units in the SAMs has been successfully tuned by simply changing the electrolyte solutions from 0.1 M n-Bu4NPF6–CH2Cl2 to aqueous 0.1 M HClO4.