Bis-tridentate chelates of an asymmetric ligand: X-ray structures and solution NMR characterization of divalent zinc triad metal ion complexes of N-(2-pyridylmethyl)-N-(2-(methylthio)ethyl)amine

Deborah C. Bebout, Wei Lai, Sarah M. Stamps, Steven M. Berry, Raymond J. Butcher

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

Divalent zinc triad metal ion complexes of type M(L)2(ClO4)2 (L = N-(2-pyridylmethyl)-N-(2-(methylthio)ethyl)amine) with N4S2 metal coordination spheres were isolated and characterized by X-ray crystallography and variable temperature proton NMR. Although bis-tridentate chelates have nine geometric isomers, the crystallographically characterized complexes of all three metal ions had trans facial octahedral coordination geometry with Ci symmetry. Despite the low coordination number and geometric preferences of d10 metal ions, which facilitate inter- and intramolecular exchange processes, dilute solutions of these bis-tridentate chelates exhibited slow geometric isomerization. Symmetry, sterics and shielding arguments supported specific isomeric assignments for the major and minor chemical shift environments observed at low temperature. At elevated temperature, rapid intramolecular exchange occurred for all three complexes but slow intermolecular exchange on the coupling constant time scale was evidenced through detection of JHgH interactions for Hg (L)22 +. These unusual observations are discussed in the context of the zinc triad metal ion coordination chemistry of related bis-tridentate chelates.

Original languageEnglish (US)
Pages (from-to)1591-1600
Number of pages10
JournalPolyhedron
Volume27
Issue number6
DOIs
StatePublished - Apr 25 2008

Keywords

  • Bis-tridentate chelate
  • Group 12
  • Isomerization
  • NMR
  • Single crystal X-ray structure

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