Spectroelectrochemical characterization of Si-bridged diphenylamines: Influence of Si-bridging upon electronic structures of diphenylamines

Spectroelectrochemical properties of monosilane bridged diphenylamine (5,10 -dihydro-2,8-diphenyl-5,10,10-trimethylphenazasiline, Phenaz) and disilane bridged diphenylamine (2,8-diphenyl-10,11-dihydro-10,11-disila-5,10,10,11,1 1-pentamethyldibenzo[b,f]azepine, DSiAzep) were investigated. The electroch emical oxidation of Phenaz was reversible and its cyclic voltammogram was a lmost the same shape as that of diphenylamine (DPA). The electrochemical ox idation of DSiAzep was followed by irreversible reactions leading to the cl eavage of the Si-Si bond. On electrochemical oxidations of Phenaz and DPA, the formation of a stable radical cation was observed with UV-Vis spectrosc opy. In comparison with the absorption characteristics of oxidized radical cations, it was seen that the oxidized radical cation of Phenaz was more de localized than that of DPA. In the same way, absorption characteristics of oxidized DSiAzep were observed to be different from those observed in Phena z and DPA.