Cobalt(III) complexes of stereospecific linear NSNN tetradentate ligands. Synthesis and characterization of ternary amino acid complexes containing tetradentate ligands with terminal amine donors

Paul J. Toscano, Kimberly A. Belsky, Terrence Nicholson, Jon Zubieta

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

The preparation and characterization of cis-β-[Co(gee)(gly)]+ (geeHN-{2-[(2-aminoethyl)thio]ethyl}-2-aminoacetamide) and cis-β-[Co(ege)(AA)]+ (egeHN-(2-aminoethyl)-2-[(2-aminoethyl)thio]acetamide; AAgly, L-ala, L-leu, L-ile) complexes as PF6- or mixed Cl-/PF6- salts are described. 1H and 13C NMR spectra of the new cobalt complexes demonstrate that only one geometrical isomer (with respect to the bidentate chelate) is obtained with very high stereoselectivity. X-ray structural studies revealed that orientation of the amino acidato chelate is the β1 configuration; that is, the isomer with the carboxylate donor of the amino acid coordinated trans to the amido function to the tetradentate backbone ligand. β1-[Co(gee)(gly)]PF6·H2O (I) crystallized in the monoclinic space group P21/a with a=11.748(2), b=11.810(2), c=12.341(3) Å, β=101.43(2)° and Z=4 and was refined to R=0.042. β1-[Co(ege)(gly)]PF6 (II) crystallized in the monoclinic space group P21/n with a=11.467(2), b=8.173(1), c=17.421(3) Å, β=106.69(2)° and Z=4 and was refined to R=0.052. The complexes, β-[Co(L)Cl2] (Lgee or ege), were found to be convenient precursors for the hydrolysis of the peptide bond of glygly to give β1-[Co(L)(gly)]+ under mild conditions.

Original languageEnglish (US)
Pages (from-to)77-82
Number of pages6
JournalInorganica Chimica Acta
Volume206
Issue number1
DOIs
StatePublished - Apr 1 1993
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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