The Fate of NHC‐Stabilized Dicarbon |
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| Authors: | Dayne C Georgiou Bradley D Stringer Dr Conor F Hogan Dr Peter J Barnard Dr David J D Wilson Dr Nicole Holzmann Prof Dr Gernot Frenking Dr Jason L Dutton |
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| Institution: | 1. Department of Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, 3086 (Australia);2. Fachbereich Chemie, Philipps‐Universit?t Marburg, Hans‐Meerwein‐Strasse 1, 35032 Marburg (Germany) |
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| Abstract: | The attempted synthesis of NHC‐stabilized dicarbon (NHC?C?C?NHC) through deprotonation of a doubly protonated precursor (NHC?CH?CH?NHC]2+) is reported. Rather than deprotonation, a clean reduction to NHC?CH?CH?NHC is observed with a variety of bases. The apparent resistance towards deprotonation to the target compound led to a reinvestigation of the electronic structure of NHC→C?C←NHC, which showed that the highest occupied molecular orbital/lowest unoccupied molecular orbital (HOMO/LUMO) gap is likely too small to allow for isolation of this species. This is in contrast to the recent isolation of the cyclic alkylaminocarbene analogue (cAAC?C?C?cAAC), which has a large HOMO–LUMO gap. A detailed theoretical study illuminates the differences in electronic structures between these molecules, highlighting another case of the potential advantages of using cAAC rather than NHC as a ligand. The bonding analysis suggests that the dicarbon compounds are well represented in terms of donor–acceptor interactions L→C2←L (L=NHC, cAAC). |
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| Keywords: | carbenes density functional calculations donor– acceptor systems ligands synthetic methods |
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