I am trying to determine Gibbs free energy of solvation for a sodium salt of an alkylcarboxylate. B3LYP/6-31g. The minimized structure makes covalent bonds between sodium and carboxylate oxygens. How do I prevent this? Thanks
How do I prevent this?
Ionic bonding is an idealization we do not expect to be realized in pure form between individual atoms, even in cases where the electronegativity differential would seem to be quite large. As described here, purely ionic bonding is more closely approached between multiatomic entities for which the molecular-orbital structure favors such bonding.
Moreover, the boundary between "ionic" and "covalent" bonding is really indistinct; what appears to be ionic bonding may in many cases have a covalent interpretation. The lattice structure of calcium carbide offers one such case.