Host-guest chemistry of 1,2-bis(chloromercurio)tetrafluorobenzene Chelation of the carbonyl oxygen atom of acetone by a bidentate Lewis acid Academic Article uri icon

abstract

  • Incremental addition of DMF or DMSO to a solution of 1,2-bis(chloromercurio)tetrafluorobenzene (3) in acetone results in a change of the199Hg NMR chemical shift of 3. The titration curves thus obtained can be fitted and indicate the formation of the 1:1 hostguest complexes 32-DMF (4) and 32-DMSO (5). The stability constants of 4 and 5 have been determined and are respectively equal to 1.8 (0.2) M-1and 8.0 (0.8) M-1. The X-ray crystal structures of 4 and 32-acetone (6) have been determined. In the structure of 4, the carbonyl oxygen atom is coordinated to three mercury atoms and has a distorted-tetrahedral geometry. In 6 however, the acetone oxygen is coordinated to only two mercury atoms and exhibits a trigonal-planar geometry. While it is difficult to detect any metrical changes undergone by the organic substrates upon chelation, the IR carbonyl stretching frequency of 4 (vCO1635 cm-1) and 6 (vCO1639 cm-1) indicates that the carbon oxygen bond is weakened. Accordingly, the13C CP/MAS NMR carbonyl carbon chemical shifts of 4 (167 ppm) and 6 (215 ppm) provide evidence for a substantial polarization of the carbonyl. By comparison of the13C CP/MAS NMR carbonyl carbon chemical shift, the Lewis acidity of 3 toward acetone can be evaluated to be just inferior to that of MgCl2. Finally, both 4 and 6 have complex and highly networked supramolecular structures which result from intermolecular HgCl and HgF or HgO contacts.

published proceedings

  • ORGANOMETALLICS

author list (cited authors)

  • Tschinkl, M., Schier, A., Riede, J., & Gabbai, F. P.

citation count

  • 46

complete list of authors

  • Tschinkl, M||Schier, A||Riede, J||Gabbaii, FP

publication date

  • April 1999