Anodic oxidation of ArSi(OEt)₃ derivatives

The electrochemical properties of 13 derivatives of triethoxysilylarenes [ArSi(OEt)₃] have been studied in acetonitrile by cyclic voltammetry (CV). They all afford irreversible oxidation waves, mostly two, but some exhibit up to four waves. No reduction waves were detected on glassy upon scanning negatively up to -2.5 V. As expected, their oxidation has been found to be easier than their aryl silanes analogs (ArSiH₃), presumably due to the participation of the lone-pair of the oxygen atoms of the ethoxy groups in the initial anodic process. By examining the surface effect, no significant difference in peak potentials was observed at Pt or GC working electrodes. Anodic oxidation of various substrates by controlled-potential electrolysis (CPE) in acetonitrile led mostly to polymers, except for the fully substituted derivative, Me₅C₆Si(OEt)₃. It was oxidized both in acetonitrile and methanol, and yielded monomeric and dimeric products, respectively, all stemmed from C-Si bonds cleavage. The nature of products and mechanism of their formation are discussed.