Isolable Silylene Anion Radical: Structural Characteristics in the Solid State and in Solution

摘要

The chemistry of stable free radicals and ion radicals of heavier group 14 elements is one of the most fascinating topics of recent years. Several group 14 element-centered radical species, as well as anion radicals of alkene and alkyne analogues of the heavier group 14 elements have been synthesized and characterized. Although only a few examples of metal-substituted silyl radical and silylene anion radical species have been reported, the isolation and structural characterization of these species has been missing until now, owing to their high reactivities and instability. Recently, Apeloig et al. reported ESR spectroscopic evidence for the lithium-substituted silyl radicals by the photochemical reactions of the silylmercury compound [Li(~iPr_3Si)_2Si-Hg-Si(Si~iPr_3)_2Li] and hydridosilyllithium (R_2SiHLi)_2 (R = SiMe~tBu_2). The reaction of the isolable silylenoid with alkali metals was also reported to generate alkali metal-substituted silyl radicals. On the other hand, the anion radicals of the heavy carbene analogues (R_2E:~(·-), E = Si, Ge, Sn) were observed by ESR spectroscopy upon the one-electron reduction of the corresponding divalent species.