To probe the possibility that carbodicarbenes (CDCs) are redox active ligands, all four members of the redox series [Fe(1) ] (n=2-5) were synthesized, where 1 is a neutral tridentate CDC. Through a combination of spectroscopy and DFT calculations, the electronic structure of the pentacation is shown to be [Fe (1 ) ] (S= ). That of [Fe(1) ] is more ambiguous, but it has significant contributions from the open-shell singlet [Fe (1)(1 )] (S=0). The observed spin states derive from antiferromagnetic coupling of their constituent low-spin iron(III) centres and cation radical ligands. This marks the first time redox activity has been observed for carbones and expands the diverse chemical behaviour known for these ligands.
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http://dx.doi.org/10.1002/anie.201809158 | DOI Listing |
Chemistry
January 2025
LCM, Ecole polytechnique, CNRS, IP Paris, 91128, Palaiseau, France.
Is the J coupling constant for protonated carbene a relevant measure of its σ-donation ability? This paper addresses this question by comparing calculated J values with various experimental and theoretical approaches across a broad spectrum of carbene compounds. We examined Arduengo-type NHCs based on the 2-imidazolylidene scaffold and many other derivatives with modified frameworks, including carbenes with extended, saturated, or conjugated rings, reduced heteroatom stabilization, alternative heteroatoms, permanently charged carbenes, acyclic carbenes, amidocarbenes, and cyclic amino(alkyl/aryl) carbenes, carbodicarbenes and carbodiphosphoranes. Our findings reveal a nuanced relationship between different parameters associated with σ-interaction, such as J, Huynh electronic parameter (HEP), σ-donation from ETS-NOCV, and lone pair energy.
View Article and Find Full Text PDFChem Sci
August 2024
Department of Chemistry, Massachusetts Institute of Technology 77 Massachusetts Avenue, Building 18-596 Cambridge MA 02139-4307 USA
Designing molecules that can undergo late-stage modifications resulting in specific optical properties is useful for developing structure-function trends in materials, which ultimately advance optoelectronic applications. Herein, we report a series of fused diborepinium ions stabilized by carbene and carbone ligands (diamino-N-heterocyclic carbenes, cyclic(alkyl)(amino) carbenes, carbodicarbenes, and carbodiphosphoranes), including a detailed bonding analysis. These are the first structurally confirmed examples of diborepin dications and we detail how distortions in the core of the pentacyclic fused system impact aromaticity, stability, and their light-emitting properties.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
August 2023
Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland.
Bent (hetero)allenes such as carbodicarbenes and carbodiphosphoranes can act as neutral C-donor ligands, and diverse applications in coordination chemistry have been reported. N-Heterocyclic diazoolefins are heterocumulenes, which can function in a similar fashion as L-type ligands. Herein, we describe the synthesis and the reactivity of an anionic diazoolefin.
View Article and Find Full Text PDFJ Am Chem Soc
January 2022
Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States.
Borenium ions, originally synthesized as fundamentally important laboratory curiosities, have attracted significant attention due to their applications in catalysis and frustrated Lewis pair chemistry. However, investigations of the materials properties of these types of compounds are exceptionally rare. Herein, we report the synthesis, molecular structures, and optical properties of a new class of air-stable borenium ions, stabilized by the strongly donating carbodicarbene (CDC) ligand (, , ).
View Article and Find Full Text PDFInorg Chem
March 2020
Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University (NTU), 21 Nanyang Link, 637371, Singapore.
Carbodicarbenes (CDCs) possess two lone pairs of electrons on their central carbone C atom (C). Coordination to a transition metal via a σ bond leaves one pair of electrons with appropriate symmetry for π donation to the metal. However, the high energy of the latter also renders the CDC ligand potentially redox-active.
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