共查询到20条相似文献,搜索用时 15 毫秒
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Daniel Pinchuk Jomon Mathew Alexander Kaushansky Dmitry Bravo‐Zhivotovskii Yitzhak Apeloig 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(35):10414-10418
Reaction of bromoacylsilane 1 (pink solution) with tBu2MeSiLi (3.5 equiv) in a 4:1 hexane:THF solvent mixture at −78 °C to room temperature yields the solvent separated ion pair (SSIP) of silenyl lithium E‐[(tBuMe2Si)(tBu2MeSi)C=Si(SiMetBu2)]− [Li⋅4THF]+ 2 a (green–blue solution). Removal of the solvent and addition of benzene converts 2 a into the corresponding contact ion pair (CIP) 2 b (violet–red solution) with two THF molecules bonded to the lithium atom. The 2 a ⇌ 2 b interconversion is reversible upon THF⇌ benzene solvent change. Both 2 a and 2 b were characterized by X‐ray crystallography, NMR and UV/Vis spectroscopy, and theoretical calculations. The degree of dissociation of the Si−Li bond has a large effect on the visible spectrum (and thus color) and on the silenylic 29Si NMR chemical shift, but a small effect on the molecular structure. This is the first report of the X‐ray molecular structure of both the SSIP and the CIP of any R2E=E′RM species (E=C, Si; E′=C, Si; M=metal). 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(26):7681-7686
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‐i Pr2C6H3) 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. 相似文献
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Tom E. Stennett Philipp Bissinger Stefanie Griesbeck Stefan Ullrich Ivo Krummenacher Michael Auth Andreas Sperlich Matthias Stolte Krzysztof Radacki Chang‐Jiang Yao Frank Würthner Andreas Steffen Todd B. Marder Holger Braunschweig 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(19):6516-6521
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Robin Guthardt Jan Oetzel Julia I. Schweizer Clemens Bruhn Robert Langer Martin Maurer Jan Vícha Pavletta Shestakova Max C. Holthausen Ulrich Siemeling 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(5):1401-1405
The N‐heterocyclic plumbylene [Fe{(η5‐C5H4)NSiMe3}2Pb:] is in equilibrium with an unprecedented dimer in solution, whose formation involves the cleavage of a strong C?H bond and concomitant formation of a Pb?C and an N?H bond. According to a mechanistic DFT assessment, dimer formation does not involve direct PbII insertion into a cyclopentadienyl C?H bond, but is best described as an electrophilic substitution. The bulkier plumbylene [Fe{(η5‐C5H4)NSitBuMe2}2Pb:] shows no dimerization, but compensates its electrophilicity by the formation of an intramolecular Fe?Pb bond. 相似文献
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