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10:44
Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
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NHC-CAAC Heterodimers with Three Stable Oxidation States
Dominik Munz1, Jiaxiang Chu1, Mohand Melaimi1
1Joint UCSD-CNRS Research Chemistry Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, 92093-0358, USA.
Angewandte Chemie (International Ed. in English)
|September 16, 2016
Summary
Researchers synthesized novel N-heterocyclic carbene (NHC)-cyclic (alkyl)(amino) carbene (CAAC) heterodimers. These unique compounds exhibit electronic properties similar to tetrathiafulvalenes (TTFs), opening new avenues in materials science.
Area of Science:
- Organometallic Chemistry
- Materials Science
Background:
- N-heterocyclic carbenes (NHCs) and cyclic (alkyl)(amino) carbenes (CAACs) are important classes of ligands.
- Synthesizing heterodimers of different carbene types presents unique challenges due to their reactivity.
Purpose of the Study:
- To develop a synthetic route for NHC-CAAC heterodimers.
- To investigate the electronic properties and redox behavior of these novel heterodimers.
- To compare their properties with established electron-rich systems like tetrathiafulvalenes (TTFs).
Main Methods:
- Addition of a free NHC to a cyclic iminium salt to form a protonated heterodimer.
- Deprotonation to yield the neutral mixed Wanzlick dimers.
- One- and two-electron oxidations to generate stable cationic radicals and bis(cations).
- Characterization using cyclic voltammetry, UV/Vis spectroscopy, spin density analysis, and DFT calculations.
Main Results:
- Successful synthesis and isolation of NHC-CAAC heterodimers.
- Isolation and full characterization of stable one- and two-electron oxidized species (cationic radicals and bis(cations)).
- Experimental and computational data indicate electronic properties complementary to TTFs.
Conclusions:
- A viable synthetic strategy for accessing NHC-CAAC heterodimers has been established.
- These heterodimers and their oxidized forms represent a new class of electronically tunable molecules.
- The findings suggest potential applications in areas requiring tunable electron-donating or redox-active materials.
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