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Stereoselectivity in Reactions of Metal Complexes. Part XV . Structure and stability of chiral cobalt(III) complexes with pentadentate ligands
Author(s) -
Bernauer Klaus,
StoeckliEvans Helen,
HugiCleary Deirdre,
Hilgers Hermann J.,
AbdelKhalek Habib,
Porret Joëlle,
Sauvain JeanJacques
Publication year - 1992
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19920750719
Subject(s) - chemistry , pyridine , methylene , stereochemistry , stereospecificity , pyrrolidine , cobalt , ligand (biochemistry) , crystal structure , medicinal chemistry , metal , sarcosine , transition metal , crystallography , inorganic chemistry , catalysis , amino acid , receptor , organic chemistry , glycine , biochemistry
The syntheses and characterization of four new linear pentadentate ligands and their Co III complexes are described: N , N ′‐[(pyridine‐2,6‐diy)bis(methylene)]bis[sarcosine] (sarmp), N , N ′‐[(pyridine‐2,6‐diyl)bis(methylene)]bis[( R )‐ or ( S )‐proline] (( R , R )‐ or ( S , S )‐promp), N , N ′‐[(pyridine‐2,6‐diyl)bis(methylene)]bis[ N ‐(methyl)‐( R )‐ or ( S )‐alanine] (( R , R )‐ or ( S , S )‐malmp); 2,2′‐[pyridine‐2,6‐diyl]bis[( S )‐ or rac ‐ N ‐(acetic acid)pyrrolidine] (( S , S )‐ or rac ‐bapap). The complexes were characterized and, with but one exception, complex formation is stereospecific: Δ‐ exo ‐( R , R ) (or Λ‐ exo ‐( S , S )) for promp and Λ‐( R , R ) (or Δ‐( S , S )) for bapap. The exception is [Co(( R , R )‐ or ( S , S )‐malmp)H 2 O]ClO 4 for which two forms are obtained, to which Λ‐ endo ‐( R , R ) (or Δ‐ endo ‐( S , S )) and, tentatively, Δ‐ unsymmetric ‐( R , R )‐ (or Λ‐ unsymmetric ‐( S , S )‐) configurations are assigned. X‐Ray crystal structures are presented for the complexes [Co(sarmp)H 2 O]ClO 4 , [Co(( S , S )‐promp)H 2 O]ClO 4 , [Co( rac ‐bapap)H 2 O]ClO 4 and endo ‐[Co( rac ‐malmp)H 2 O]ClO 4 . Ligand acid dissociation and Co II and Fe II complex‐formation constants are reported.