Dismutational and Global‐Minimum Isomers of Heavier 1, 4‐Dimetallatetrasilabenzenes of Group 141. Issue 13 (26th February 2014)

• Record Type: Journal Article
• Authors: Jana, Anukul; Huch, Volker; Repisky, Michal; Berger, Raphael J. F.; Scheschkewitz, David
• Is Part Of: Angewandte Chemie international edition. Volume 53:Issue 13(2014)
• Page Start: 3514
• Page End: 3518
• Publication Date: 2014-02-26
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201310475
• Languages: English
• ISSNs: 1433-7851

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Aromatic species with heavier Group 14 elements show remarkable differences in terms of stability, structure, and reactivity. Herein we report our experimental and theoretical investigations regarding isomers of germanium‐ and tin‐containing benzene analogues E₂Si₄R₆ (E=Ge, Sn). The germanium‐substituted dismutational isomer with a tricyclic six‐membered scaffold is isolable, but unlike the homonuclear Si₆ analogue slowly rearranges even at room temperature to give the propellane‐type global minimum isomer. In case of E=Sn the dismutational isomer may be an intermediate on the pathway to the propellane‐type species obtained, but cannot be detected even at low temperature. Unprecedentedly large chemical shift anisotropies in the ²⁹Si NMR spectra that increase from the Si₆ species through Ge₂Si₄ to Sn₂Si₄ are rationalized by progressively larger paramagnetic‐term contributions to the chemical shift tensor as a result of diminishing HOMO–LUMO gaps, which are also reflected in the absorption spectra, as well as by appearance and symmetry of these frontier orbitals.</p> </abstract>