RESUMEN
Abinitio molecular orbital calculations were performed for the chalcognides and the corresponding positive ions of the group IV p-block elements [Ge, Sn and Pb] at HF and MP levels using the Effective Core Potential with the appropriate d-functions on each atom. The theoretically predicted molecular parameters, bond lengths and dipole moment, agreed with experimental data. Calculations revealed that the bond lengths of the investigated molecules were greater than those of corresponding positive ions, while values of the dipole moment, bond order, and the stability of the HOMO and LUMO were less. The calculated stabilities, according to the total energy [E[T]], the bond length [R[e]] and the dissociation energy [D[e]], followed similar trends as the oxides, i.e., in the order GeO > SnO > PbO