Atropochiral (C,C)-chelating NHC-ylide ligands: synthesis and resolution of palladium(II) complexes thereof

Dalton Trans. 2009 Sep 21:(35):7196-202. doi: 10.1039/b907019b. Epub 2009 Jul 23.

Abstract

Atropochiral NHC-phosphonium ylides based on the naphthyl-benzimidazolyl core are targeted as strongly sigma-donor C,C-chelating ligands of transition metals. The ligand core is shown to act in either a monodentate (through the carbene center) or bidentate (through the carbene and the ylide centers) fashion in seven palladium(ii) complexes obtained by two sequential strategies. In particular, the enantiomerically pure ortho-palladated (S)-dimethyl(1-phenylethyl)amine co-ligand is used as the chiral resolving agent for the separation of diastereoisomeric NHC-ylide complexes by fractional crystallization. Hydrochloric treatment of either diastereoisomer was found to keep intact the two carbon-palladium bonds, while affording the corresponding enantiomeric beta-zwitterionic NHC-ylide palladate complexes. The absolute configuration of the chirally isolated C,C-chelating ligand was finally confirmed by X-ray crystallography.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chelating Agents / chemistry*
  • Crystallography, X-Ray
  • Heterocyclic Compounds / chemistry*
  • Ligands
  • Methane / analogs & derivatives*
  • Methane / chemistry
  • Models, Molecular
  • Molecular Structure
  • Organometallic Compounds / chemical synthesis*
  • Organometallic Compounds / chemistry*
  • Palladium / chemistry*
  • Stereoisomerism

Substances

  • Chelating Agents
  • Heterocyclic Compounds
  • Ligands
  • Organometallic Compounds
  • carbene
  • Palladium
  • Methane