Molecular modeling of interactions betweenD-talopyranose andD-talofuranose conformers and Pb2+and Hg2+cations was done in the gaseous state using the AM1 method, both with "naked" species and with some water molecules added. A complete conformational analysis of the freeD-talose molecule was carried out using a Monte Carlo method (BATCHMIN program). Lower minima were identified, and the different orientations of the hydroxyl groups given. The calculated equilibrium distribution of anomers in the gaseous phase differs from that obtained experimentally in aqueous solution. This could be related to the predominance of intramolecular hydrogen bonding for the isolated molecule and intermolecular hydrogen bonding in aqueous media. In the presence of a cation, the analysis was carried out using the AM1 method for every conformation of the ligand. In the gaseous phase, Angyal's predictions are not respected. The lowest energy is represented by a flexible β-pyranosic form and some complexes are tetra or pentacoordinated. For the furanosic species, the αF forms bearing acis-cis-cissequence of hydroxyl groups are the less stable. Amongst the complexes of carbohydrates with metal cations in aqueous solutions, Pb2+forms complexes and Hg2+does not. The calculations show that, for the isolated complexes, the reverse should be true. The lesser stability in water of Hg2+complexes with respect to Pb2+could be interpreted in terms of (1) a more unfavourable entropic hydration effect; (2) a less favourable difference of translational entropy. A complete answer requires the dynamical study of the system in water by a Monte Carlo method.Keywords: complexes with divalent cations,D-talopyranose andD-talofuranose conformers.