Our research group is interested in examining correlations between X-ray crystal structures and 199Hg and 113Cd NMR chemical shifts for thiacrown complexes containing these two divalent heavy metal ions.  These types of correlations could assist in the further advancement of chemosensors for heavy metal ions by providing key information regarding their solution structures.  We have focused on macrocyclic thioether complexes of heavy metals since nuclei like 199Hg and 113Cd are attractive and amenable for study by NMR, yet surprisingly little data exist for them.  We report our NMR results for a series of Hg(II) and Cd(II) complexes containing thiacrown ligands as well as some related azacrowns and mixed nitrogen-sulfur donor ligands.  Trends in NMR chemical shifts related to the number of thioether sulfur donors, replacement of a sulfur donor by a nitrogen donor, and the size of the macrocyclic ring will be presented.  We also report a series of homoleptic Hg(II) and Cd(II) complexes involving related mixed donor macrocyclic oxygen-sulfur ligands.  In examining the coordination behavior of the oxa azacrown 18N2O4 (1,10-diaza-4,7,13,16-tetraoxacyclooctadecane) towards Cd(II), we have discovered that the complex reacts with atmospheric carbon dioxide.  Its unusual crystal structure shows three [Cd(18N2O4)]2+ complexes bridged in �3 fashion by a single carbonate ion, formed from activated CO2.

Heavy metal complexes with thiacrowns and related macrocyclic ligands

243rd National Meeting (2012)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.