Back to Search
Start Over
Supramolecular anion binding by the [ZnCl(HpztBu)<SUB>3</SUB>]+ cation (HpztBu = 5-tert-butylpyrazole)
- Source :
- Journal of the Chemical Society, Dalton Transactions; November 14, 2002, Vol. 2002 Issue: 22 p4206-4212, 7p
- Publication Year :
- 2002
-
Abstract
- Reaction of ZnCl<SUB>2</SUB> with three molar equivalents of 3{5}-tert-butylpyrazole (Hpz<superscript>t</superscript>Bu) yields [ZnCl(Hpz<superscript>t</superscript>Bu)<SUB>3</SUB>]Cl (<compoundref>1</compoundref>). Treatment of <compoundref>1</compoundref> with an appropriate Ag(i) or Tl(i) salt gives [ZnCl(Hpz<superscript>t</superscript>Bu)<SUB>3</SUB>]X (X<superscript>−</superscript> = BF<SUB>4</SUB><superscript>−</superscript>, <compoundref>4</compoundref>; X<superscript>−</superscript> = ClO<SUB>4</SUB><superscript>−</superscript>, <compoundref>5</compoundref>; X<superscript>−</superscript> = NO<SUB>3</SUB><superscript>−</superscript>, <compoundref>6</compoundref>; X<superscript>−</superscript> = CF<SUB>3</SUB>SO<SUB>3</SUB><superscript>−</superscript>, <compoundref>7</compoundref>; X<superscript>−</superscript> = PF<SUB>6</SUB><superscript>−</superscript>, <compoundref>8</compoundref>). Crystal structures of all of the complexes show a [ZnCl(Hpz<superscript>t</superscript>Bu)<SUB>3</SUB>]<superscript>+</superscript> cation, with (for <compoundref>1</compoundref> and <compoundref>4</compoundref>-<compoundref>7</compoundref>) only small deviations from C<SUB>3v</SUB> symmetry, with the tert-butyl groups forming a bowl-shaped cavity on one face of the complex. The X<superscript>−</superscript> anion binds within this cavity, via hydrogen bonding to the three pyrazole NH groups. For <compoundref>8</compoundref>, the PF<SUB>6</SUB><superscript>−</superscript> guest only interacts with two NH donors, the third pyrazole ring being twisted away from the anion. We attribute this to steric repulsions between the third ligand and the PF<SUB>6</SUB><superscript>−</superscript> anion, which is larger than the other guests used in this study. <superscript>1</superscript>H, <superscript>13</superscript>C and <superscript>19</superscript>F NMR, ESMS and IR studies provide good circumstantial evidence for these structures being retained in solution, although the guest anions undergo rapid intermolecular exchange by NMR that cannot be frozen out above 190 K.
Details
- Language :
- English
- ISSN :
- 03009246
- Volume :
- 2002
- Issue :
- 22
- Database :
- Supplemental Index
- Journal :
- Journal of the Chemical Society, Dalton Transactions
- Publication Type :
- Periodical
- Accession number :
- ejs3953897