Chiral metal complexes. 19. Chiral discrimination between diastereoisomers of [(2,4-pentanedionato)(N,N′-di-8-quinolyl-1,2-diaminoethane)cobalt(III)]

Paul Jones, Peter A. Williams*, Robert S. Vagg

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

The 360 MHz 1H NMR spectrum of a synthetic isomeric mixture of Δ,Λ-β-[Co(dqen)(acac)]2+ ions (where dqen is N,N′-di-8-quinolyl-1,2-diaminoethane and acac is the 2,4-pentanedionate anion) has been measured in 6 M DCl. Two sets of completely resolved signals have been assigned uniquely to the Δ-β-(S,S) and Δ-β-(R,S) diastereoisomers, together with their enantiomeric forms, where R and S refer to the absolute configuration of the two amine nitrogen atoms of the tetradentate dqen ligand. Integration of the spectrum permits the calculation of the chiral discrimination energy difference between the two forms of the complex cation at 298 K. This quantity emerges as only 0.44 kJ mol-1 in favour of the Δ-β-(S,S) isomer. The results are discussed with reference to other similar complexes, especially those in which the geometry of the in-plane amine nitrogen atom of the coordinated tetradentate is determined by the steric requirements of substituents on the aliphatic back bone of the dqen ligand.

Original languageEnglish
Pages (from-to)49-52
Number of pages4
JournalInorganica Chimica Acta
Volume103
Issue number1
DOIs
Publication statusPublished - 2 Sep 1985

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