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A Mono‐Substituted Silicon(II) Cation: A Crystalline “Supersilylene”
Author(s) -
Hinz Alexander
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202009874
Subject(s) - chemistry , nucleophile , silicon , substituent , lone pair , lewis acids and bases , moiety , reactivity (psychology) , amine gas treating , silylene , oxidation state , medicinal chemistry , crystallography , photochemistry , stereochemistry , organic chemistry , molecule , catalysis , medicine , alternative medicine , pathology
Mono‐coordinated silicon(II) cations are predicted to be reactive ambiphiles, combining the typically high Lewis acidity of silicon cations with nucleophilicity due to the presence of an electron pair at the same atomic centre. Here, a carbazole‐derived scaffold was used to isolate salts with a mono‐coordinated silicon(II) cation, [RSi] + (R=bulky carbazolyl substituent), by halide abstraction from a base‐free halosilylene, RSiI, with Ag[Al(O t Bu F ) 4 ]. Despite the bulk of the carbazolyl moiety, the silylenylium cation [RSi] + retains high reactivity. It was shown to react with an amine to form three bonds at the silicon atom in one reaction which conforms with the notion of a “supersilylene”. The resulting silylium cation [RSi(H)NR′ 2 ] + (in the formal oxidation state Si IV ) obtained by oxidative addition of an NH bond at [RSi] + is even more acidic than the silylenylium cation (Si II ) due to the absence of a lone pair of electrons the silicon atom.