Extending, and repositioning, a thermochemical ladder: high-level quantum chemical calculations on the sodium cation affinity scale.

High-level ab initio quantum chemical calculations, at the CP-dG2thaw level of theory, are reported for coordination of Na+ to a wide assortment of small organic and inorganic ligands. The ligands range in size from H to C6H6, and include 22 of the ligands for which precise relative sodium ion binding free energies have been determined by recent Fourier transform ion cyclotron resonance and guided ion beam studies. Agreement with the relative experimental values is excellent (+/-1.