Faculté des sciences

Carbonate binding to copper(II) in solution: mixed-ligand complex formation and its application to the isolation and separation of the three isomers of [Cu(bpp)(H2O)][ClO4]2 [bpp = 2,6-bis(pyrrolidin-2-yl)pyridine]

Bernauer, Klaus ; Godefroy, Isabelle ; Cabort, Amel ; Guicher, Nathalie ; Stoeckli-Evans, Helen ; Süss-Fink, Georg

In: Journal of the Chemical Society, Dalton Transactions, 2002, p. 2069-2073

The binding of the carbonate anion to [Cu(meso-bpp)(H2O)]2+ and rac-[Cu(bpp)(H2O)]2+ [bpp = 2,6-bis(pyrrolidin-2-yl)pyridine] in aqueous solution has been investigated. Formation constants of the carbonato complexes [Cu(meso-bpp)(CO3)] and rac-[Cu(bpp)(CO3)] (1.02 × 103 M–1 and... Plus

Ajouter à la liste personnelle
    Summary
    The binding of the carbonate anion to [Cu(meso-bpp)(H2O)]2+ and rac-[Cu(bpp)(H2O)]2+ [bpp = 2,6-bis(pyrrolidin-2-yl)pyridine] in aqueous solution has been investigated. Formation constants of the carbonato complexes [Cu(meso-bpp)(CO3)] and rac-[Cu(bpp)(CO3)] (1.02 × 103 M–1 and 1.77 × 103 M–1, respectively, µ= 0.70 M) have been calculated from spectrophotometric measurements. The formation of these Cu2+ complexes can also be used for an improved synthesis and an easy isolation of the three diastereoisomers of bpp. The mixture of [Cu(meso-bpp)(H2O)]2+ and rac-[Cu(bpp)(H2O)]2+ is separated by elution from SP Sephadex C-25, either as hydroxo or carbonato derivatives. rac-[Cu(bpp)(H2O)]2+ is then resolved into the enantiomers [Cu(S,S-bpp)(H2O)]2+ and [Cu(R,R-bpp)(H2O)]2+, again on SP Sephadex C-25, by means of L-(+)-tartrate as chiral eluent. The three stereoisomers, meso-bpp, (S,S)-bpp and (R,R)-bpp are liberated from the corresponding copper(II) complexes by ligand displacement using trans-1,2-diaminocyclohexane-N,N,N’,N’-tetraacetic acid (H4cdta). The structure of the meso isomer was solved by a single crystal X-ray analysis using the perchlorate salt [meso-bppH2][ClO4]2•2H2O.