Novel pentacoordinated bridged silicon anions

Both ab initio and semiempirical electronic structure calculations are used to investigate the molecular and electronic structures and eneregetic stabilities of an unusual bridged compound with the general formula [Y? SiH₃? X? SiH₃? Y]^?, with Y = H or F and X = H, CH₃, NH₂, OH, F, or Cl. Most of these bridged anions are quite stable relative to YSiH₃ + XSiH₃Y^?, and the stability is predicted to increase considerably when Y = H is replaced with Y = F.