Uncovering Nitrosyl Reactivity at N-Heterocyclic Carbene Center |
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Authors: | Junbeom Park Jaelim Kim Gu Yoon Jeong Prof Dr Youngsuk Kim Prof Dr Eunsung Lee |
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Institution: | 1. Department of Chemistry, Pohang University of Science and Technology, Pohang, 37673 Republic of Korea;2. Department of Chemistry, Pusan National University, Busan, 46241 Republic of Korea |
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Abstract: | N-heterocyclic carbenes (NHCs) have garnered much attention due to their unique properties, such as strong σ-donating and π-accepting abilities, as well as their transition-metal-like reactivity toward small molecules. In 2015, we discovered that NHCs can react with nitric oxide (NO) gas to form radical adducts that resemble transition metal nitrosyl complexes. To elucidate the analogy between NHC and transition metal NO adducts, here we have undertaken a systematic investigation of the electron- and proton-transfer chemistry of NHC−NO]⋅ (N-heterocyclic carbene nitric oxide radical) compounds. We have accessed a suite of compounds, comprised of NHC−NO]+, NHC−NO]−, NHC−NOH]0, and NHC−NHOH]+ species. In particular, NHC−NO]− was isolated as potassium and lithium ion adducts. Most interestingly, a monomeric potassium NHC−NO]− compound was isolated with the assistance of 18-crown-6, which is the first instance of a monomeric alkali N-oxyl compound to the best of our knowledge. Our results demonstrate that NHC−NO]⋅ exhibits redox behavior broadly similar to metal nitrosyl complexes, which opens up more possibilities for utilizing NHCs to build on the known reactivity of metal complexes. |
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Keywords: | Metal Nitroxyl Complex N-Heterocyclic Carbene Nitric Oxide |
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