TY - JOUR
T1 - Trapping a Silicon(I) Radical with Carbenes
T2 - A Cationic cAAC–Silicon(I) Radical and an NHC–Parent-Silyliumylidene Cation
AU - Li, Yan
AU - Chan, Yuk Chi
AU - Leong, Bi Xiang
AU - Li, Yongxin
AU - Richards, Emma
AU - Purushothaman, Indu
AU - De, Susmita
AU - Parameswaran, Pattiyil
AU - So, Cheuk Wai
N1 - Publisher Copyright:
© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2017/6/19
Y1 - 2017/6/19
N2 - The trapping of a silicon(I) radical with N-heterocyclic carbenes is described. The reaction of the cyclic (alkyl)(amino) carbene [cAACMe] (cAACMe=:C(CMe2)2(CH2)NAr, Ar=2,6-iPr2C6H3) with H2SiI2 in a 3:1 molar ratio in DME afforded a mixture of the separated ion pair [(cAACMe)2Si:.]+I− (1), which features a cationic cAAC–silicon(I) radical, and [cAACMe−H]+I−. In addition, the reaction of the NHC–iodosilicon(I) dimer [IAr(I)Si:]2 (IAr=:C{N(Ar)CH}2) with 4 equiv of IMe (:C{N(Me)CMe}2), which proceeded through the formation of a silicon(I) radical intermediate, afforded [(IMe)2SiH]+I− (2) comprising the first NHC–parent-silyliumylidene cation. Its further reaction with fluorobenzene afforded the CAr−H bond activation product [1-F-2-IMe-C6H4]+I− (3). The isolation of 2 and 3 confirmed the reaction mechanism for the formation of 1. Compounds 1–3 were analyzed by EPR and NMR spectroscopy, DFT calculations, and X-ray crystallography.
AB - The trapping of a silicon(I) radical with N-heterocyclic carbenes is described. The reaction of the cyclic (alkyl)(amino) carbene [cAACMe] (cAACMe=:C(CMe2)2(CH2)NAr, Ar=2,6-iPr2C6H3) with H2SiI2 in a 3:1 molar ratio in DME afforded a mixture of the separated ion pair [(cAACMe)2Si:.]+I− (1), which features a cationic cAAC–silicon(I) radical, and [cAACMe−H]+I−. In addition, the reaction of the NHC–iodosilicon(I) dimer [IAr(I)Si:]2 (IAr=:C{N(Ar)CH}2) with 4 equiv of IMe (:C{N(Me)CMe}2), which proceeded through the formation of a silicon(I) radical intermediate, afforded [(IMe)2SiH]+I− (2) comprising the first NHC–parent-silyliumylidene cation. Its further reaction with fluorobenzene afforded the CAr−H bond activation product [1-F-2-IMe-C6H4]+I− (3). The isolation of 2 and 3 confirmed the reaction mechanism for the formation of 1. Compounds 1–3 were analyzed by EPR and NMR spectroscopy, DFT calculations, and X-ray crystallography.
KW - carbenes
KW - cations
KW - low-valent homologues
KW - radicals
KW - silicon
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U2 - 10.1002/anie.201702760
DO - 10.1002/anie.201702760
M3 - Article
C2 - 28544030
AN - SCOPUS:85019561403
SN - 1433-7851
VL - 56
SP - 7573
EP - 7578
JO - Angewandte Chemie - International Edition
JF - Angewandte Chemie - International Edition
IS - 26
ER -