Table 14. Hydrogen Bonding Energies for Phosphates in kcal/mol: Deviations in Comparison to G3B3a.
| moleculeb | G3B3 | MP2c | B3LYPc | B3LYPd | PBEd | PM6-SPe | PDDG | MIO | 3OB | 3OB/OPhyd |
|---|---|---|---|---|---|---|---|---|---|---|
| MMPH–OH2 | 13.3 | +0.2 | –1.9 | –0.4 | +1.0 | –5.4 | –2.8 | –2.0 | –2.7 | –2.7 |
| MMP–1–H2O | 17.9 | –0.4 | –2.7 | –1.1 | –0.3 | –5.2 | –3.1 | –0.6 | –1.1 | –1.3 |
| MMP–1–OH2 | 17.4 | +0.1 | –2.0 | –1.0 | +0.6 | –4.8 | –3.5 | –1.3 | –2.0 | –2.1 |
| MMP–2–H2O | 32.3 | –0.4 | –3.2 | –0.9 | +0.5 | –4.5 | +2.4 | –0.5 | –0.6 | –0.7 |
| DMPH–OH2 | 14.4 | +0.0 | –2.1 | –0.5 | +0.8 | –5.3 | –3.2 | –2.9 | –3.7 | –3.8 |
| DMP–1–H2O | 18.1 | –0.6 | –2.9 | –1.3 | –0.6 | –5.2 | –3.0 | –1.0 | –1.4 | –1.6 |
| MAD | 0.3 | 2.5 | 0.9 | 0.6 | 5.1 | 3.0 | 1.4 | 1.9 | 2.0 | |
| MAX | 0.6 | 3.2 | 1.3 | 1.0 | 5.4 | 3.5 | 2.9 | 3.7 | 3.8 |
a
The binding energy is computed with the potential energies at 0 K without any zero-point energy correction.
b
MMPH: dihydrogenated monomethylphosphate. MMP–1: monohydrogenated momomethylphosphate. MMP–2: dehydrogenated monomethylphosphate, respectively for DMP: dimethylphosphate; coordinates are given in the Supporting Information.
c
Basis set is aug-cc-pVTZ.
d
Basis set is 6-31+G(d,p).
e
During the geometry optimization using PM6, the hydrogen bonds relaxe to substantially different minima. Therefore, single-point calculations have been used for comparison.