Calculations on some phosphate ions by a modified CNDO method

Calculations are presented of the electronic structures of some phosphate ions, namely, H₃PO₄, H₂PO₄^–, HPO₄⁼, PO₄, HPO₃, and PO₃^–. It is shown that the character of the P-O bonds is marked and the 3d orbitals contribute substantially to the bonding. Using the total energy data for the orthophosphate ions, the ratio of the dissociation constants for the ions is calculated and found to be in good agreement with the experimental data.