Bis(hypersilyl)tin and Bis(hypersilyl)lead, Two Electron-Rich Carbene Homologs

摘要

Molecular compounds of divalent tin and lead (siannylenes and plumbylenes, respectively) with solely electropositive a-bonded substituents tend to oligomerize or to disproportionate, respectively. It has previously been possible to stabilize such systems by introduction of sterically demanding groups or additional coordinative saturation of the central atom. Typical examples are bis(trimcthylsilyl)methyl arid bis(trimcthylsilyi)-amino derivatives, stannylenes and plumbylenes bearing aryl substituents,' or intermolecularly donor-stabilized compounds such as Sn[P(CMe)_2]_2l or Sn[E(SiMe_3)_2]_2 (E = P, As). Furthermore, several heteroleptic plumbylenes and stannylenes are known. In the solid state the homoleptic stannylenes are either dimeric or monomeric, in the gas phase those studied to date have only been monomeric. The corresponding lead compounds were observed as monomers in ail aggregate states. Stannylenes and plumbylenes with stronger electropositive subslituents were to date unknown. The synthesis and the structural characterization of two such derivatives. namely bis(hypersilyl)tin (1), and bis(hypersilyl)iead (2). is the subject of this communication.