Si(II) cation-promoted formation of an abnormal NHC-bound silylene and a cAAC-silanyl radical ion

• Main Authors: Zhu, Keke, Dutta, Sayan, Han, Weichun, Wang, Chenfeng, Lee, Jiawen, Tan, Gengwen, Koley, Debasis, So, Cheuk-Wai, Li, Yan
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2022
• Subjects: Science::Chemistry; Aromatic Compounds; Chemical Bonds
• Online Access: https://hdl.handle.net/10356/159525
• Institution: Nanyang Technological University

The reaction of amidinatosilylene LSi(:)Cl [L = PhC(NtBu)2] with N-heterocyclic carbene IAr [:C{N(Ar)CH}2, where Ar = 2,6-iPr2C6H3] and NaOTf in tetrahydrofuran (THF) facilely afforded a silicon(II) cation [LSi(:)-aIAr]+OTf- (1+OTf-), where IAr isomerizes to abnormal N-heterocyclic carbene aIAr, coordinating to the silicon(II) center. Its Ge homologue, [LGe(:)-aIAr]+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 IAr in THF. In contrast, the replacement of IAr 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.