The first direct observation of the tautomeric equilibrium between mesoionic imidazolium aminides (IA) and amino NHCs (AC) shows its dependence on the aminide substituent. A potassium (imidazol-2-ylidenyl)(anilide), an ion-pair with the 'free' anionic NHC, and potassium organometallic polymers, with the repeat unit exhibiting 'Janus-type' coordination, are reported.
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http://dx.doi.org/10.1039/c3cc49517e | DOI Listing |
J Org Chem
October 2024
Institute of Organic Chemistry, Clausthal University of Technology, Leibnizstraße 6, D-38678 Clausthal-Zellerfeld, Germany.
Mesoionic compounds are the starting material for the synthesis of unique anionic N-heterocyclic carbenes. Herein, mesoionic imidazolium pyrrolides synthesized from pyrrole-2-carbaldehyde via various -alkyl-4-pyrroyl-imidazoles are described. These were converted into nine new 4-(pyrrol-2-yl)-substituted imidazolium salts and transformed into the mesoionic title compounds using an anion exchange resin.
View Article and Find Full Text PDFBeilstein J Org Chem
December 2023
Laboratory of Catalysis, MolSys Research Unit, Université de Liège, Institut de chimie organique (B6a), Allée du six août 13, 4000 Liège, Belgium.
The synthesis of zwitterionic dithiocarboxylate adducts was achieved by deprotonating various aldiminium or 1,2,3-triazolium salts with a strong base, followed by the nucleophilic addition of the in situ-generated cyclic (alkyl)(amino) or mesoionic carbenes (CAACs or MICs) onto carbon disulfide. Nine novel compounds were isolated and fully characterized by H and C NMR, FTIR, and HRMS techniques. Moreover, the molecular structures of two CAAC·CS and two MIC·CS betaines were determined by X-ray diffraction analysis.
View Article and Find Full Text PDFChemistry
June 2022
Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland.
Dichalcogenolenes are archetypal redox non-innocent ligands with numerous applications. Herein, a diselenolene ligand with fundamentally different electronic properties is described. A mesoionic diselenolene was prepared by selenation of a C2-protected imidazolium salt.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
March 2020
Georg-August Universität Göttingen, Institut für Organische und Biomolekulare Chemie, Tammannstr. 2, 37077, Göttingen, Germany.
We report a new class of stable mesoionic N-heterocyclic olefins, featuring a highly polarized (strongly ylidic) double bond. The ground-state structure cannot be described through an uncharged mesomeric Lewis-structure, thereby structurally distinguishing them from traditional N-heterocyclic olefins (NHOs). mNHOs can easily be obtained through deprotonation of the corresponding methylated N,N'-diaryl-1,2,3-triazolium and N,N'-diaryl-imidazolium salts, respectively.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
February 2019
Inorganic Chemistry and Catalysis Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India.
The reaction of SIPr, [1,3-bis(2,6-diisopropylphenyl)-imidazolin-2-ylidene] (1), with C F led to the formation of an unprecedented mesoionic compound (2). The formation of 2 is made accessible by deprotonation of the SIPr backbone with simultaneous elimination of HF. The C-F bond para to the imidazolium ring in 2 is only of 1.
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