Novel diastereoisomers of ethylenediaminetetrapropionato-chromate(III). Part 1. Preparation and characterization

Abstract

Hexadentate ethylenediaminetetraacetato-like chromate(III) complexes were prepared with ethylenediamine-N,N,N′,N′-tetrapropionate (edtp), (S)-propane-1,2-diamine-N,N,N′,N′-tetrapropionate [(S)-pdtp] and (1S,2S)-trans-cyclohexane-1,2-diamine-N,N,N′,N′-tetrapropionate [(SS)-cydtp] ligands. For each complex, QAE-Sephadex column chromatography demonstrated three isomers, which were characterized by ²H NMR and circular dichroism (CD) spectra to be novel diastereoisomers arising from a pairwise combination of two chiral ethylenic gauche conformations at the six-membered propionate rings. Two of the diastereoisomers were found to undergo thermal hydrolysis with anomalous carbon–nitrogen bond cleavage in aqueous solution to give diamine-tripropionato complexes and 3-hydroxypropionic acid.