(1,1'-ferrocenediyl)dimethylsilane: an electroactive monolayer derivatizing reagent. Characterization of surface-oxygen-(dimethylsilyl)ferrocene by cyclic voltammetry and solid-state nuclear magnetic resonance

(1,1'-Ferrocenediyl)dimethylsilane (I) has been used to functionalize the surfaces of smooth Au, smooth Pt, single-crystal n-type (100) Si, (111) Si, and (111) Ge, textured (100) Si, and rough (111) Ge electrodes. For the smooth surfaces the coverage of electroactive material is between 3.5 x 10/sup -10/ and 4.9 x 10/sup -10/ mol/cm/sup 2/ for a large number of independent preparations. This coverage is consistent with an approximate monolayer of the ferrocene. The textured and rough surfaces give larger coverages consistent with an increase in the effective coverage by a factor of approx. 2 to 5. The E/sup 0/' for the surface-confined ferrocene in CH/sub 3/CN/0.1 M (n-Bu/sub 4/N)C1O/sub 4/ on Pt or Au is +0.43 V vs. SCE. The full width of cyclic voltammetry waves at half-height on Pt and Au is approx. 210 mV, consistent with nonideality in surface activities. Solid-state cross-polarization/magic-angle spinning, natural abundance, /sup 29/Si, and /sup 13/C NMR of high surface area silica (400 m/sup 2//g) bearing approx. 10/sup -11/ mol/cm/sup 2/ of ferrocene-centered material confirms the mode of attachment of I to be surface-O-(dimethylsilyl)ferrocene. The /sup 29/Si NMR shows a single resonance due to surface-anchored material at approx. +7 ppM (relative to tetramethylsilane) consistent withmore » the -O-SiMe/sub 2/Fe structure (Fc = ferrocenyl) and the /sup 13/C NMR shows a singlet at approx. 0 ppM (relative to tetramethylsilane) for the methyl carbons and an unresolved multiplet at approx. +69 ppM (relative to tetramethylsilane) for the nonequivalent cyclopentadienyl carbons.« less