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 journalArticlepeer-review

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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