Synthesis of an NHC-Coordinated Dialkyldisilavinylidene and Its Oxidation Providing a Silicon Analog of an Acetolactone

Abstract

Although isolable silicon analogs of acetylene have been extensively studied, the silicon analogs of vinylidene, which is a short-lived isomer of acetylene, remain scarce. Herein, we report isolable NHCcoordinated dialkyldisilavinylidene 1 synthesized by the reduction of a tetrabromodisilane featuring a bulky alkyl protecting group. 1 was fully characterized by a combination of multinuclear NMR spectroscopy, highresolution mass spectrometry, elemental analysis, and X-ray diffraction analysis. The UV−vis spectrum and DFT calculations disclosed that 1 possesses an SiSi double bond and lone pair electrons on the terminal Si atom coordinated by the NHC. 1 reacted with N 2 O and B(C 6 F 5 ) 3 to provide a silicon analog of an acetolactone stabilized by a Lewis base and a Lewis acid (4). * sı Supporting InformationThe Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.organomet.1c00130.Experimental and theoretical details (PDF)Cartesian coordinates of the calculated structure (XYZ)Accession Codes CCDC 2065387−2065388 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk

Phosphine-Stabilized Germasilenylidene: Source for a Silicon-Atom Transfer

“…The Si−P bond length can be compared with a cyclic phoshine-stabilized silylene [Si−P 2.304( 5) Å] and the Si−P distances found in 3 and in 4. 19,27,70 The 29 Si NMR signals of 6 were found at 98.4 ppm (dd, 3 J PSi = 38.5 Hz, 3 J PSi = 106.7 Hz) and −122.6 ppm (dd, 5 J PSi = 8.5 Hz, 1 J PSi = 221.1 Hz). The germasilene exhibits a signal at higher frequencies that is comparable with the signals found for published examples: cyclic germasilene, 75.8 ppm; 29 acyclic germasilenes, 144.0 ppm [(tBuMe 2 Si) 2 SiGe(SitBuMe 2 ) 2 ] 32 and 146.9 ppm [(Mes) 2 SiGe(SitBu 2 Me) 2 ].…”

“…Vinylidenes are transient isomers of acetylenes and are elusive in all-carbon chemistry. − Heavier homologues are of fundamental interest, and a few examples have been experimentally accessed only very recently. − Heteroheavy vinylidenes are still extremely rare and have also been investigated by computational studies. , In studying the potential energy surface of the SiGeH 2 system, the research groups of O’Leary and Boone found local minima for the vinylidene-type isomers silagermenylidene A and germasilenylidene B (Figure ). While the double hydride-bridged butterfly isomer C is the global minimum in both studies, vinylidene-type isomer B is about 10 kcal mol –1 higher in energy than isomer A .…”

“… However, the chemistry of isomer B is as of yet unexplored. Disilavinylidene ( D ), which is also stabilized by an NHC donor, was characterized by Filippou et al after reduction of an NHC-stabilized bromo­(silyl)­silylene. , A boryl-substituted digermavinylidene ( F ) is exhibited in the solid-state weak stabilizing contacts between the one-coordinate germanium atom and flanking aryl groups . We reported the synthesis of a phosphine-stabilized digermavinylidene ( G ), which was shown to transfer a germanium atom in a reaction with organoazides .…”

Conformationally Switchable Silylone: Electron Redistribution Accompanied by Ligand Reorientation around a Monatomic Silicon

“…Unlike the NHC-stabilized disilavinylidene E (Chart ) reported by Filippou and co-workers which features a Si–C NHC bond length [1.937(4) Å] typical for Si–C single bonds, the Si1–Si2 bond length in both 1 and 2 [ 1 (mol. 1): 2.2329(16), 1 (mol.…”

Recent Advances in the Chemistry of Heavier Group 14 Analogues of Carbonyls

“…In 2021, Iwamoto and coworkers reported that exposure of the NHC-coordinated disilavinylidene 67 to an atmosphere of N 2 O, followed by addition of a benzene solution of B(C 6 F 5 ) 3 , afforded the NHC/B(C 6 F 5 ) 3 -stabilized disilaacetolactone 68 (Scheme 14). [48] In the 29 Si NMR spectrum of 68, the resonance corresponding to the Si=O moiety was detected at À 69.7 ppm, which is comparable to that of À 49.1 ppm in 53. The Si=O bond length of 1.562(3) Å in 68 is slightly longer than that of 1.5347(18) Å in 53.…”