Chemistry of functionalized silylenes

Abstract

Recent years have witnessed important developments in organosilicon chemistry, courtesy to the high yield access of stable monomeric chlorosilylene (LSiCl, L = PhC(NtBu)₂) and N-heterocyclic carbene (NHC) stabilized dichlorosilylene (L¹SiCl₂, L¹ = 1,3-bis(2,6-iPr₂C₆H₃)imidazol-2-ylidene) by dehydrochlorination technique using strong bases such as N-heterocyclic carbenes or LiN(SiMe₃)₂ as HCl scavenger. The chemistry of functionalized silylenes is markedly different from the previously reported dicoordinate silylenes. Their utility as synthons is well documented which paves the way for several striking compounds, e.g. monosilaoxiranes, CSi₂P derivative, CSi₃P cation, a dimer of silaisonitrile (Si₂N₂) with dicoordinate Si atoms etc. This study also unravels that these functionalized silylenes are proficient at activating phosphorus, and the functional group attached to the α-position of the silicon(II) centre plays a key role to determine the final product. The reaction of P₄ with LSiCl affords a zwitterionic Si₂P₂ ring, while with LSiN(SiMe₃)₂ it gives an acyclic Si₂P₄ derivative. Another recent achievement in this field is the successful isolation of a valence isomer of disilyne known as the inter-connected bis-silylene. This perspective portrays the chemistry of functionalized silylenes which will attract great attention, heading for the further development of organosilicon chemistry.