Absolute configurational assignment of serf-organizing asymmetric tripodal ligand-metal complexes

Jesus M. Castagnetto, Xiaodong Xu, Nina D. Berova, James W. Canary

Research output: Contribution to journalArticle

Abstract

The solution configuration of labile coordination complexes may be difficult to determine, even in cases in which the solid state structure is known. We have previously synthesized a series of chiral ligands which form pseudo-C3-symmetric complexes with Zn(II) and Cu(II) salts that possess an available electrophilic coordination site. Molecular modeling of Zn(II) complexes of the chiral ligand N,N-bis[(2-quinolyl)methyl]1-(2- pyridyl)ethanamine (α-MeBQPA) showed that the spatial arrangement of the heterocyclic arms is controlled by a substituent on one methylene arm, resulting in the adoption of an enantiomeric conformation displaying a propeller-like asymmetry. In this paper we report the application of the exciton chirality method to the determination of the conformation of asymmetric metal-ligand complexes in solution. There is a good correlation between the predicted and the observed Cotton effects, demonstrating that the geometry in solution closely resembles that predicted by computational simulations and those obtained by X-ray crystallographic studies of metal complexes with racemic and enantiomerically pure ligands. The X-ray crystallographic structure of the first optically pure complex in this series is reported.

Original languageEnglish (US)
Pages (from-to)616-622
Number of pages7
JournalChirality
Volume9
Issue number5-6
DOIs
StatePublished - 1997

Keywords

  • Absolute stereochemistry
  • C-symmetry
  • Chiral coordination complex
  • Exciton coupling
  • Tripodal li- gand

ASJC Scopus subject areas

  • Analytical Chemistry
  • Catalysis
  • Pharmacology
  • Drug Discovery
  • Spectroscopy
  • Organic Chemistry

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