Chapter 82. The Zwitterionic Spirocyclic λ5 Si-Silicate [(Dimethylammonio)methyl] bis-[salicylato(2–)-O1, O3] silicate: Experimental and Computational Studies

  1. Prof. Norbert Auner2 and
  2. Prof. Johann Weis3
  1. Melanie Pülm,
  2. Reiner Willeke and
  3. Reinhold Tacke

Published Online: 28 APR 2008

DOI: 10.1002/9783527619917.ch82

Organosilicon Chemistry IV: From Molecules to Materials

Organosilicon Chemistry IV: From Molecules to Materials

How to Cite

Pülm, M., Willeke, R. and Tacke, R. (2000) The Zwitterionic Spirocyclic λ5 Si-Silicate [(Dimethylammonio)methyl] bis-[salicylato(2–)-O1, O3] silicate: Experimental and Computational Studies, in Organosilicon Chemistry IV: From Molecules to Materials (eds N. Auner and J. Weis), Wiley-VCH Verlag GmbH, Weinheim, Germany. doi: 10.1002/9783527619917.ch82

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. Institut für Anorganische Chemie, Universität Würzburg Am Hubland, D-97074 Würzburg, Germany Tel.: Int. code + (931)888 5250 —Fax: Int. code f (931)888 4609

Publication History

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

ISBN Information

Print ISBN: 9783527298549

Online ISBN: 9783527619917

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Keywords:

  • pentacoordinate silicon;
  • zwitterionic;
  • crystal structures;
  • ab initio studies;
  • stereochemistry

Summary

The zwitterionic spirocyclic λ5 Si-silicate [(dimethylammonio)methyl]-bis[salicylato(2–)-O1,O3]silicate (6) was synthesized by two different methods, and the crystal structures of the acetonitrile solvate 6a. 0.7CH3CN and the isomeric compound 6b were determined by single-crystal X-ray diffraction. In addition, ab initio studies of 6a, 6b, and the related anionic model species hydridobis[salicylato(2–)-O1,O3]silicate(1–) (7) were carried out (SCF/SVP geometry optimizations). The experimentally established structures of the two crystallographically independent zwitterions (molecules A and B) in the crystal of 6a.0.7CH3CN are characterized by trigonal-bipyramidal Si-coordination polyhedra, with the carboxylate oxygen atoms in the axial sites. As opposed to this, one carboxylate oxygen atom and one alcoholate oxygen atom occupy the axial sites of the trigonal-bipyramidal Si-coordination polyhedron of the isomeric zwitterion 6b. The experimentally established structures of the zwitterions in the crystals of 6a.0.7CH3CN and 6b are similar to those calculated for 6a and 6b, respectively (SCFISVP geometry optimizations). The energetically preferred isomer of the anionic model species 7, the anion 7a, is characterized by a trigonal-bipyramidal Si-coordination polyhedron, with both carboxylate oxygen atoms in the axial sites, thus corresponding to the structure of 6a.