Silylium Ions Stabilized by an Si–X–Si Three-center Bond (X = Halogen or Hydrogen)

Silylium ions stabilized by Si–X–Si three-center bonds (X = halogen or hydrogen) (2a–d) have been synthesized by the reaction of the corresponding 1-tris(trimethylsilyl)methyl-2,3-bis(trimethylsilyl)-1-silacyclopropene derivatives (1a–d) with triethylsilyl benzenium tetrakis(pentafluorophenyl)borate. Structural and theoretical studies of 2a–d showed Si–X–Si three-center bonding with halonium ion character for 2a–c, and 3c–2e Si–H–Si bonding for 2d.