Hydroxy- and mercaptopyridine pincer platinum and palladium complexes generated by silver-free halide abstraction

Inorg Chem. 2006 Mar 6;45(5):2045-54. doi: 10.1021/ic051773x.

Abstract

A silver-free route has been employed for the synthesis of a number of Pd and Pt complexes supported by an NCN "pincer" ligand (NCN = [2,6-(Me2NCH2)2C6H3]-) via halide abstraction. This was achieved by the use of o-, m-, and p-hydroxypyridines or o- and p-mercaptopyridines in basic ethanol solutions. The acidic OH or SH protons are removed to generate the formally anionic ligands. X-ray crystal structure determination of these complexes shows that the bonding of the substituted pyridine ligands occurs exclusively through the pyridine N for hydroxypyridines and exclusively through the thiol S in mercaptopyridines. In the hydroxypyridine case, the ortho and para isomers tautomerize to generate pyridone structures with a covalent M-N bond, whereas the m-hydroxypyridine complex, which is unable to tautomerize, is found to still be bound through the pyridine N but in a zwitterionic structure. The mercaptopyridine complexes are the first reported examples of pincer-ligated Pd and Pt thiolate species. The pyridine ligands can be quantitatively exchanged for chloride by reaction with excess NH4Cl, a potentially useful chemical switch for ligation/decomplexation of this ligand type.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chemistry, Inorganic / methods*
  • Crystallography, X-Ray
  • Ligands
  • Organometallic Compounds / chemical synthesis
  • Organometallic Compounds / chemistry*
  • Palladium / chemistry
  • Platinum / chemistry
  • Pyridines / chemistry
  • Pyridines / metabolism
  • Silver / chemistry

Substances

  • Ligands
  • Organometallic Compounds
  • Pyridines
  • Silver
  • Platinum
  • Palladium
  • 2-thiopyridine