title: Synthesis of a pentasilapropellane. Exploring the nature of a stretched silicon-silicon bond in a nonclassical molecule.
abstract: We report on the successful synthesis of Si(5)Mes(6) (Mes = 2,4,6-trimethylphenyl), which consists of an archetypal [1.1.1] cluster core featuring two ligand-free, "inverted tetrahedral" bridgehead silicon atoms. The separation between the bridgehead Si atoms is much longer, and the bond strength much weaker, than usually observed for a regular Si-Si single bond. A detailed analysis of the electronic characteristics of Si(5)Mes(6) reveals a low-lying excited triplet state, indicative of some biradical(oid) character. Reactivity studies provide evidence for both closed-shell and radical-type reactivity, confirming the unusual nature of the stretched silicon-silicon bond in this "nonclassical" molecule.
authors.affiliation: Faculty of Chemistry and Biosciences, Karlsruhe Institute of Technology, Kaiserstrasse 12, D-76131 Karlsruhe, Germany.
authors.forename: Dominik
authors.initials: D
authors.lastname: Nied
authors.forename: Ralf
authors.initials: R
authors.lastname: Köppe
authors.forename: Wim
authors.initials: W
authors.lastname: Klopper
authors.forename: Hansgeorg
authors.initials: H
authors.lastname: Schnöckel
authors.forename: Frank
authors.initials: F
authors.lastname: Breher