Electrochemical fabrication and characterization of thin films of redox-active molecular wires based on extended Rh–Rh bonded chains

Abstract

An original electrochemical synthesis of {[Rh₄(μ-OOCCH₃)₄(phen)₄]²⁺}_n (1) molecular wire films from a solution of binuclear bridged Rh complexes [Rh₂(μ-OOCCH₃)₂(phen)₂(X)₂](Y)₂ (X = H₂O, Y = BF₄⁻ (2a) and X = CH₃CN, Y = BF₄⁻ (2b)) in MeCN electrolyte is reported. UV-vis spectroscopy and quartz crystal microbalance electrochemical coupled techniques have been used to demonstrate the electrosynthesis process. The resulting polymetallic compound 1 has been characterized on the basis of its physicochemical properties, which have been compared with those of a chemically synthesized sample. Furthermore, according to EPR, ¹H NMR and electrochemical behaviour, the mechanism of the oxidation of this polymetallic wire, containing mixed valent rhodium centers and alternatively acetate bridged Rh–Rh bonds, has been investigated in detail.