Complexes of Co(III) with L-sorbose and phenanthroline

Abstract

L-Sorbose and two molecules of 1,10-phenanthroline form a complex with Co(III) which has the Lambda configuration about Co(III), based on CD and ORD spectra, The H-1 NMR signals of alpha-L-sorbopyranose and its mixed Co(III)(phen)(2) complex have been assigned. Signals of H-6 and H-6' of the sugar are shifted strongly upfield because of shielding by the aromatic residues, but shifts are much smaller for H-1 and H-1'. These observations are consistent with molecular modelling with MM2 parameters, which predicts that the most stable complex is the Lambda diastereomer with complexation at positions 1 and 2. The characteristics of the NMR spectra and the predicted structure of the complex differ From those of the corresponding complex of D-fructose.