Chapter 22. Silyl Effects in Hypercoordinated Carbocations

  1. Prof. Norbert Auner2 and
  2. Prof. Johann Weis3
  1. Hans-Ullrich Siehl and
  2. Martin Fuß

Published Online: 28 APR 2008

DOI: 10.1002/9783527619917.ch22

Organosilicon Chemistry IV: From Molecules to Materials

Organosilicon Chemistry IV: From Molecules to Materials

How to Cite

Siehl, H.-U. and Fuß, M. (2000) Silyl Effects in Hypercoordinated Carbocations, in Organosilicon Chemistry IV: From Molecules to Materials (eds N. Auner and J. Weis), Wiley-VCH Verlag GmbH, Weinheim, Germany. doi: 10.1002/9783527619917.ch22

Editor Information

  1. 2

    Inst. für Anorganische Chemie, der Universität Frankfurt, Marie-Curie-Strasse 11, D-60439 Frankfurt am Main, Germany, Phone: 0 69/7 98-29180, -29591, Fax: 069/798-29188

  2. 3

    Wacker-Chemie GmbH, Geschäftsbereich S, Werk Burghausen, Johannes-Hess-Strasse 24, D-84489 Burghausen, Germany

Author Information

  1. Abteilung für Orgunische Chemie I, Universität Ulm D-89069 Ulm, Germany Tel.: Int. code + (731)502 2800

Publication History

  1. Published Online: 28 APR 2008
  2. Published Print: 17 JAN 2000

ISBN Information

Print ISBN: 9783527298549

Online ISBN: 9783527619917



  • silyl effects;
  • stable carbocations;
  • NMR;
  • ab initio calculations


The 1-(trimethylsilyl)bicyclobutonium ion and the 3-endo-(tert-butyldi-methylsily1)bicyclobutonium ion were investigated by NMR spectroscopy in superacid solution and by quantum chemical ab initio calculations. The 1–(trimethyl-silyl)bicyclobutonium ion undergoes a threefold degenerate methylene rearrangement. The 3-endo-(tert-butyldimethylsilyl)bicyclobutonium ion is the first static bicyclo-butonium ion. The NMR spectra of this carbocation are a direct proof for the hypercoordinated and puckered structure of bicyclobutonium ions.