NHC-Supported 2-Sila and 2-Germavinylidenes: Synthesis, Dynamics, First Reactivity and Theoretical Studies.

Autor: Kumar S; Institut für Anorganische Chemie, Universität Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany., Maurer LR; Institut für Anorganische Chemie, Universität Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany., Schnakenburg G; Institut für Anorganische Chemie, Universität Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany., Das U; Institut für Anorganische Chemie, Universität Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany., Filippou AC; Institut für Anorganische Chemie, Universität Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany.
Jazyk: angličtina
Zdroj: Angewandte Chemie (International ed. in English) [Angew Chem Int Ed Engl] 2024 Jul 29; Vol. 63 (31), pp. e202400227. Date of Electronic Publication: 2024 Feb 26.
DOI: 10.1002/anie.202400227
Abstrakt: 2-tetrelavinylidenes (C=EH 2 ; E=Si, Ge) are according to quantum chemical studies the least stable isomers on the [E,C,2H] potential energy hypersurface isomerizing easily via the trans-bent tetrelaacetylenes HE≡CH to the thermodynamically most stable 1-tetrelavinylidenes (E=CH 2 ). Consequently, experimental studies on 2-tetrelavinylidenes (C=ER 2 ) and their derivatives are lacking. Herein we report experimental and theoretical studies of the first N-heterocyclic carbene (NHC) supported 2-silavinylidene (NHC)C=SiBr(Tbb) (1-Si: NHC=C[N(Dipp)CH] 2 , Dipp=2,6-diisopropylphenyl, Tbb=2,6-bis[bis(trimethylsilyl)methyl]-4-tert-butylphenyl) and the isovalent 2-germavinylidenes (NHC)C=GeBr(R) (1-Ge, 1-GeMind: R=Tbb, Mind (1,1,3,3,5,5,7,7-octamethyl-s-hydrindacene-4-yl)). The NHC-supported 2-tetrelavinylidenes were obtained selectively from the 1,2-dibromoditetrelenes (E)-(R)BrE=EBr(R) using the diazoolefin (NHC)CN 2 as vinylidene transfer reagent. 1-E (E=Si, Ge) have a planar vinylidene core, a bent-dicoordinated vinylidene carbon atom (C VNL ), a very short E=C VNL bond and an almost orthogonal orientation of the NHC five-membered ring to the vinylidene core. Quantum chemical analysis of the electronic structures of 1-E suggest a significantly bent 1-tetrelaallene and tetrelyne character. NMR studies shed light into the dynamics of 1-E involving NHC-rotation around the C VNL -C NHC bond with a low activation barrier. Furthermore, the synthetic potential of 1-E is demonstrated by the synthesis and full characterization of the unprecedented NHC-supported bromogermynes BrGe=C(EBr 2 Tbb)(NHC) (2-SiGe: E=Si; 2-GeGe: E=Ge).
(© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)
Databáze: MEDLINE
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