One- and Two-Electron Transfer Oxidation of 1,4-Disilabenzene with Formation of Stable Radical Cations and Dications

Abstract

Electron-transferable oxidants such as B(C6F5)3/nBuLi, B(C6F5)3/LiB(C6F5)4, B(C6F5)3/LiHBEt3, Al(C6F5)3/(o-RC6H4)AlH2 (R=N(CMe2CH2)2CH2), B(C6F5)3/AlEt3, Al(C6F5)3, Al(C6F5)3/nBuLi, Al(C6F5)3/AlMe3, (CuC6F5)4, and Ag2SO4, respectively were employed for reactions with (L)2Si2C4(SiMe3)2(C2SiMe3)2 (L=PhC(NtBu)2, 1). The stable radical cation [1]+. was formed and paired with the anions [nBuB(C6F5)3]− (in 2), [B(C6F5)4]− (in 3), [HB(C6F5)3]− (in 4), [EtB(C6F5)3]− (in 5), {[(C6F5)3Al]2(μ-F)]− (in 6), [nBuAl(C6F5)3]− (in 7), and [Cu(C6F5)2]− (in 8), respectively. The stable dication [1]2+ was also generated with the anions [EtB(C6F5)3]− (9) and [MeAl(C6F5)3]− (10), respectively. In addition, the neutral compound [(L)2Si2C4(SiMe3)2(C2SiMe3)2][μ-O2S(O)2] (11) was obtained. Compounds 2–11 are characterized by UV-vis absorption spectroscopy, X-ray crystallography, and elemental analysis. Compounds 2–8 are analyzed by EPR spectroscopy and compounds 9–11 by NMR spectroscopy. The structure features are discussed on the central Si2C4-rings of 1, [1]+., [1]2+, and 11, respectively.