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σ-Aromaticity in an Unsaturated Ring: Osmapentalene Derivatives Containing a Metallacyclopropene Unit.
- Source :
-
Angewandte Chemie International Edition . Mar2015, Vol. 54 Issue 10, p3102-3106. 5p. - Publication Year :
- 2015
-
Abstract
- In general, aromaticity can be clarified as π- and σ-aromaticity according to the type of electrons with major contributions. The traditional π-aromaticity generally describes the π-conjugation in fully unsaturated rings whereas σ-aromaticity may stabilize fully saturated rings with delocalization caused by σ-electron conjugation. Reported herein is an example of σ-aromaticity in an unsaturated three-membered ring (3 MR), which is supported by experimental observations and theoretical calculations. Specifically, when the 3 MR in cyclopropaosmapentalene is cleaved by ethane through two isodesmic reactions, both of them are highly endothermic (+29.7 and +35.0 kcal mol−1). These positive values are in sharp contrast to the expected exothermicity, thus indicating aromaticity in the 3 MR. Further nucleus-independent chemical shift and anisotropy of the current-induced density calculations reveal the nature of σ-aromaticity in the unsaturated 3 MR. [ABSTRACT FROM AUTHOR]
- Subjects :
- *AROMATICITY
*METALLACYCLES
*ALLENE
*OSMIUM
*DENSITY functional theory
Subjects
Details
- Language :
- English
- ISSN :
- 14337851
- Volume :
- 54
- Issue :
- 10
- Database :
- Academic Search Index
- Journal :
- Angewandte Chemie International Edition
- Publication Type :
- Academic Journal
- Accession number :
- 101140330
- Full Text :
- https://doi.org/10.1002/anie.201411220