. Author manuscript; available in PMC: 2013 Nov 13.

Published in final edited form as: J Chem Theory Comput. 2012 Sep 12;8(11):4405–4412. doi: 10.1021/ct300613v

Table 3.

Free energies (see 2) for the neutral/anion cycle (eg. $H_{3} P O_{4} \to H_{2} P O_{4}^{-}$ ), in kcal/mol. Shown are (1) the gas phase basicities computed from G3 calculation, (3) and (4) are the polarization contribution for the neutral species and the anion, (5) is the solvation free energy of the neutral compound obtained from thermodynamic integration using optimized radii (see text for details), (6=3+5+8-1-4-7) is the computed target value of the solvation free energy to make the Pearson sum equals to zero, (7) the proton hydration energy, and (8) the energy from the experimentally determined pKa's.

Energy	Phosphate	Methyl Phosphate	p-Tolyl Phosphate	Dimethyl Phosphate	Diethyl Phosphate
1	321.3	323.3	317.5	326.5	323.5
3	7.8	4.2	5.1	3.4	3.5
5	-16.1	-17.3	-16.2	-13.4	-12.5
7^{Ref. 30}	-252.5	-252.5	-252.5	-252.5	-252.5
8	2.7³⁴	2.0³⁵	1.9³⁶	1.8³⁴	1.9³⁴
4	8.7	8.1	9.6	4.9	6.6
6	-83.1	-90.0	-83.8	-87.2	-84.7