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.