Stable Carbenes or Betaines?
- The anisotropy effect in H-1 NMR spectroscopy can be readily employed to indicate the position of carbene/betaine mesomeric equilibria. NR2 substituted carbene/betaines tend to adopt betaine structures, whereas in the absence of NR2 substituents, the betaine structures cannot stabilise the structure through both -donation effects of the NMe2 groups and the electronegativity of the nitrogen atoms, and the corresponding carbene-like structures are preferred. These conclusions are supported by calculated bond orders and (C-13)/ppm values. The spatial magnetic properties of isonitriles and carbon monoxide, which can be counted as stable carbenes or, at least, as carbene-analogues, also exist as stable betaine structures, which is again supported by structural and magnetic properties.
| Author details: | Erich KleinpeterORCiDGND, Andreas KochORCiDGND |
|---|---|
| DOI: | https://doi.org/10.1002/ejoc.201800462 |
| ISSN: | 1434-193X |
| ISSN: | 1099-0690 |
| Title of parent work (English): | European journal of organic chemistry |
| Publisher: | Wiley-VCH |
| Place of publishing: | Weinheim |
| Publication type: | Article |
| Language: | English |
| Date of first publication: | 2018/04/16 |
| Publication year: | 2018 |
| Release date: | 2021/11/17 |
| Tag: | Betaines; Carbenes; Conformation analysis; Mesomerism; NMR spectroscopy; Through-space NMR shieldings (TSNMRS) |
| Volume: | 2018 |
| Issue: | 24 |
| Number of pages: | 8 |
| First page: | 3114 |
| Last Page: | 3121 |
| Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Chemie |
| DDC classification: | 5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften |
| Peer review: | Referiert |
