Chiral metal complexes. 49. Structural studies of ternary Co(III) complexes of N,N′-di (2S-pyrrolidin-2-yl)-1S, 2S-diaminocyclohexane and α-aminoacids

Michael A. Cox, Frederick S. Stephens, Robert S. Vagg, Peter A. Williams

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Ternary complexes of the type Δ-β1,2-[Co(S,S,S,S,-pychxn)(aa)]2+ where S,S,S,S-pychxn is N,N′-di(2S-pyrrolidin-2-yl)-1S,2S-diaminocyclohexane and aa is an aminoacidate (glyH = glycine, alaH = alanine) have been synthesized and structurally characterized. Δ-β1-[Co(S,S,S,S-pychxn)-(gly)](ClO4) 2 2H2O is orthorhombic, space group P212121, with a = 10.133(2), b = 14.418(2), c = 19.646(5) Å and Z = 4. The structure was refined to R = 0.065 and Rw = 0.072 for 2224 reflections with I >3σ(I) Δ-β2-[Co(S,S,S,S-pychxn) (R-ala)](ClO4)2.2H2O is orthorhombic, space group P212121, with a = 10.933(4), b = 13.667(2), c = 18.853(3) Å, and Z = 4. This structure was refined to R = 0.040 and Rw = 0.033 for 2221 reflections with I > 3σ(I). Both complex structures are analogous in that the coordination of the tetradentate is identical with both nitrogen atoms of coordinated pyrrolidyl groups adopting S absolute configurations; the two internal nitrogen atoms have opposite configurations with that at the fold of the tetradentate being R. While S,S,S,S-pychxn is not absolutely stereospecific with respect to its coordination with Co(III) it is markedly more so than its congener S,R,R,S,-pychxn. The structural study benchmarks stereochemistries adopted by this class of compound with respect to further studies.

Original languageEnglish
Pages (from-to)275-290
Number of pages16
JournalJournal of Coordination Chemistry
Volume41
Issue number4
DOIs
Publication statusPublished - 1997

Keywords

  • aminoacid
  • cobalt(III)
  • stereochemistry
  • tetradentate
  • x-ray structures

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