AbstractOxidation of the 1,3,2‐diazaborole tBuNaCH=CHNb(tBu)BBr(Na–B) (1h) with NO+PF6– afforded the diazaborolium salts [tBuNa=CH–CH=Nb(tBu)BF2(Na–B)]+X– (X = Br–, Br3–, PF6–) (3h) as the result of different oxidation processes. The same product was obtained when the 1,3,2‐diazaborolidine tBuNaCH2CH2Nb(tBu)BBr(Na–B) (2h) was subjected to reaction with NO+PF6–. In contrast to this, oxidation of 1h and 2h with NO+BF4– cleanly furnished [tBuNaCH–CH=Nb(tBu)BFBr(Na–B)]+BF4– (6h). Treatment of the 1,3,2‐diazaboroles tBuNaCH=CHNb(tBu)BR(Na–B) [R = H (1e), CN (1i), C≡CH (1j)] with NO+PF6– under comparable conditions led to the borolium salts [tBuNa=CH–CH=Nb(tBu)BRF(Na–B)]+PF6– [R = H (3e), CN (3i), C≡CH (3j)]. All the borolium salts investigated in this study were reversibly reduced by cyclic voltammetry. The novel products were characterized by elemental analyses and NMR spectra (1H, 11B, 13C, 19F, 31P). The X‐ray structure analysis of 3h reveals two independent planar cations in the asymmetric unit, accompanied by one bromide and one tribromide ion.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)