Preparation of Chemically Derivatized Platinum and Gold Electrode Surfaces. Synthesis, Characterization, and Surface Attachment of Trichlorosilylferrocene, (1,1'-Ferrocenediyl)dichlorosilane, and 1,1'-Bis(triethoxysilyl)ferrocene

The synthesis and characterization of three ferrocene-centered, hydrolytically unstable, surface derivatizing reagents and their attachment to pretreated (anodized) Pt and Au electrode surfaces are described. Trichlorosilylferrocene (I) has been isolated from the reaction of SiCl4 and lithioferrocene; (1,1'-ferrocenediyl)dichlorosilane (II) has been isolated from the reaction of SiCl4 and 1,1'-dilithioferrocene; and 1,1'-bis(triethoxysilyl)ferrocene (III) has been isolated from reaction of ClSi(OEt)3 with 1,1'-dilithioferrocene. The species I, II, and III have been fully characterized by 1H NMR, mass, and UV-vis spectra and elemental analyses. All are moisture sensitive and are capable of derivatizing anodized Pt surfaces. Detailed studies for derivatization of anodized Au using II are described. In many respects the properties of derivatized Au electrodes parallel those for derivatized Pt. Such derivatized electrodes exhibit persistent cyclic voltammetric waves at a potential expected for an electroactive ferrocene derivative. Greater than monolayer coverages are found in each case, as determined by the integration of the cyclic waves. The cyclic voltammetric parameters are as expected for a reversible, one-electron, surface-attached electroactive system except that the peak widths are broader than theoretical. This is attributed to chemically distinct ferrocene centers resulting from the oligomerization of the derivatizing reagent during the derivatization procedure.