Metal–ion interactions with carbohydrates. Crystal structure and FT-IR study of the SmCl3–ribose complex Original Research Article

A single-crystal of SmCl3·C5H10O5·5H2O was obtained from methanol–water solution and its structure determined by X-ray. Two forms of the complex as a pair of anomers and related conformers were found in the single-crystal in a disordered state. One ligand is α-d-ribopyranose in the 4C1 conformation and the other one is β-d-ribopyranose. The anomeric ratio is 1:1. Both ligands provide three hydroxyl groups in ax–eq–ax orientation for coordination. The Sm3+ ion is nine-coordinated with five Sm–O bonds from water molecules, three Sm–O bonds from hydroxyl groups of the d-ribopyranose and one Sm–Cl bond. The hydroxyl groups, water molecules and chloride ions form an extensive hydrogen-bond network. The IR spectral C–C, O–H, C–O, and C–O–H vibrations were observed to be shifted in the complex and the IR results are in accord with those of X-ray diffraction.