The reaction of decamethylsilicocene, (Me ₅ C ₅ ) ₂ Si, with the proton-transfer reagent Me ₅ C ₅ H ₂ ⁺ B(C ₆ F ₅ ) ₄ ^– produces the salt (Me ₅ C ₅ )Si ⁺ B(C ₆ F ₅ ) ₄ (2), which can be isolated as a colorless solid that is stable in the absence of air and moisture. The crystal structure reveals the presence of a cationic π complex with an η ⁵ -pentamethylcyclopentadienyl ligand bound to a bare silicon center. The ²⁹ Si nuclear magnetic resonance at very high field (δ = – 400.2 parts per million) is typical of a π complex of divalent silicon. The (η ⁵ -Me ₅ C ₅ )Si ⁺ cation in 2 can be regarded as the “resting state” of a silyliumylidene-type (η ¹ -Me ₅ C ₅ )Si ⁺ cation. The availability of 2 opens new synthetic avenues in organosilicon chemistry. For example, 2 reacted with lithium bis(trimethylsilyl)amide to give the disilene E -{(η ¹ -Me ₅ C ₅ )[N(SiMe ₃ ) ₂ ]Si} ₂ (3).