Conformationally Switchable Silylone: Electron Redistribution Accompanied by Ligand Reorientation around a Monatomic Silicon

Taichi Koike, Takumi Nukazawa, Takeaki Iwamoto

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


Complexes that could be switched between two electronic states by external stimuli have attracted much attention for their potential application in molecular devices. However, a realization of such a phenomenon with low-valent main-group element-centered complexes remains challenging. Herein, we report the synthesis of cyclic (alkyl)(amino)silylene (CAASi)-ligated monatomic silicon(0) complexes (silylones). The bis(CAASi)-ligated silylone adopts a π-localized ylidene structure (greenish-black color) in the solid state and a π-delocalized ylidene structure (dark-purple color) in solution that could be reversibly switched upon phase transfer (ylidene [L: →:Si = L ↔ L = Si: ←:L]). The observed remarkable difference in the physical properties of the two isomers is attributed to the balanced steric demand and redox noninnocent character of the CAASi ligand which are altered by the orientation of the two terminal ligands with respect to the Si-Si-Si plane: twisted structure (π-localized ylidene) and planar structure (π-delocalized ylidene). Conversely, the CAASi/CDASi-ligated heteroleptic silylone (CDASi = cyclic dialkylsilylene) only exhibited the twisted π-localized ylidene structure regardless of the phase. The synthesized silylones also proved themselves as monatomic silicon surrogates. Thermolysis of the silylones in the presence of an ethane-1,2-diimine afforded the corresponding diaminosilylenes. Analyses of the products suggested a stepwise mechanism that proceeds via a disilavinylidene intermediate.

Original languageEnglish
Pages (from-to)14332-14341
Number of pages10
JournalJournal of the American Chemical Society
Issue number35
Publication statusPublished - 2021 Sep 8

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry


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