Low‐Temperature Isolation of a Labile Silylated Hydrazinium‐yl Radical Cation, [(Me 3 Si) 2 N−N(H)SiMe 3 ] .+

The oxidation of silylated hydrazine, (Me 3 Si) 2 N−N(H)SiMe 3 , with silver salts led to the formation of a highly labile hydrazinium‐yl radical cation, [(Me 3 Si) 2 N−N(H)SiMe 3 ] .+ , at very low temperatures (decomposition > −40 °C). EPR, NMR, DFT and Raman studies revealed the formation of a nitrogen‐centered radical cation along the N−N unit of the hydrazine. In the presence of the weakly coordinating anion [Al{OCH(CF 3 ) 2 } 4 ] − , crystallization and structural characterization in the solid state were achieved. The hydrazinium‐yl radical cation has a significantly shortened N−N bond and a nearly planar N 2 Si 3 framework, in contrast to the starting material. According to DFT calculations, the shortened N−N bond has a total bond order of 1.5 with a π‐bond order of 0.5. The π bond can be regarded as a three‐π‐electron, two‐center bond.