Si(II) Cation-Promoted Formation of an Abnormal NHC-Bound Silylene and a cAAC-Silanyl Radical Ion

Keke Zhu; Sayan Dutta; Weichun Han; Chenfeng Wang; Jiawen Lee; Gengwen Tan; Debasis Koley; Cheuk-Wai So; Yan Li

doi:10.1021/acs.inorgchem.1c00188

Si(II) Cation-Promoted Formation of an Abnormal NHC-Bound Silylene and a cAAC-Silanyl Radical Ion

Inorg Chem. 2021 May 17;60(10):7143-7149. doi: 10.1021/acs.inorgchem.1c00188. Epub 2021 May 5.

Authors

Keke Zhu¹, Sayan Dutta², Weichun Han¹, Chenfeng Wang¹, Jiawen Lee³, Gengwen Tan⁴, Debasis Koley², Cheuk-Wai So³, Yan Li^{1

3}

Affiliations

¹ Key Laboratory of Organosilicon Chemistry and Material Technology of Ministry of Education, Hangzhou Normal University, Hangzhou 311121, China.
² Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur 741246, India.
³ Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371.
⁴ College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China.

PMID: 33950667
DOI: 10.1021/acs.inorgchem.1c00188

Abstract

The reaction of amidinatosilylene LSi(:)Cl [L = PhC(NtBu)₂] with N-heterocyclic carbene I_Ar [:C{N(Ar)CH}₂, where Ar = 2,6-iPr₂C₆H₃] and NaOTf in tetrahydrofuran (THF) facilely afforded a silicon(II) cation [LSi(:)-_aI_Ar]⁺OTf^- (1⁺OTf^-), where I_Ar isomerizes to abnormal N-heterocyclic carbene _aI_Ar, coordinating to the silicon(II) center. Its Ge homologue, [LGe(:)-_aI_Ar]⁺OTf^- (2⁺OTf^-), was also accessed via the same protocol. For the formation of 1⁺, we propose that an in situ-generated Si(II) cation [LSi(:)]⁺ under the treatment of LSi(:)Cl with NaOTf may isomerize I_Ar in THF. In contrast, the replacement of I_Ar with cyclic alkyl(amino) carbene (cAAC) furnished a cAAC-silanyl radical ion [LSi(H)-cAAC]^•+(LiOTf₂)^- [3^•+(LiOTf₂)^-], which may undergo an abstraction of the H radical from THF. All of the products were characterized by nuclear magnetic resonance spectroscopy, electron paramagnetic resonance, and X-ray crystallography, and their bonding scenarios were investigated by density functional theory calculations. These studies provide new perspective on carbene-silicon chemistry.