Donor-stabilized silyl cations. 12.1 electrochemical evidence for ionic dissociation of hexacoordinate silicon complexes

Viatcheslav Jouikov, Boris Gostevskii, Inna Kalikhman, Daniel Kost

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7 Scopus citations


Molar conductivities (Am) were measured for four formally hexacoordinate silicon dichelates (1-4) in CH2Cl2, to support previous NMR evidence suggesting ionic dissociation. Concentration dependence of the conductivities at constant temperature revealed substantial ionic conductivity and ion-pair formation in 2 and 3, lower (kinetically controlled) conductivity of 1, and practically no ionic dissociation of 4. Temperature dependence of the molar conductivities shows an increase of A m of 2 and 3 with increasing temperature, resulting from the decrease in solvent viscosity, as expected from a fully ionic solute. In contrast, the conductivities of 1 and 4 decrease as the temperature is increased, indicating chemical control of ion concentration: decrease in ionic dissociation and predominance of the hexacoordinate silicon form as the temperature is increased. These results are in full agreement with previous 29Si NMR measurements: complexes with either bulky (3) or very good leaving groups (2) as monodentate ligands are essentially fully ionic at room temperature; those with poorer leaving groups or highly electron withdrawing ligands (1, 4) tend to resist dissociation, and the extent of dissociation increases as the temperature is lowered.

Original languageEnglish
Pages (from-to)5791-5798
Number of pages8
Issue number24
StatePublished - 19 Nov 2007

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry


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