Table 7.
Water interactions with the 2’-hydroxyl group of R3PS. Interaction energies (IE, kcal mol−1) are calculated at the RIMP2/cc-pVQZ level of theory following geometry optimization with the MP2/6–31+G* model chemistry. Distances (Å) were calculated from the MP2/6-31+G* optimized geometries. Base, O3’, and O4’ geometries are as defined by Denning and MacKerell,[24] and the exact value of the C1’-C2’-O2’-H2’ dihedral for each selected geometry is shown in parenthesis.
| QM | Drude-2017 | |||
|---|---|---|---|---|
| Base (60°) | IE | r | IE | r |
| H2’ donor | −2.49 | 2.04 | −1.19 | 2.04 |
| O2’ bis | −6.41 | 2.27 | −6.51 | 2.04 |
| O2’ lp 180 | −2.24 | 3.60 | −3.30 | 3.34 |
| Avg. Diff. | 0.05 | −0.11 | ||
| Abs. Avg. Diff. | 0.82 | 0.16 | ||
| Base (90°) | IE | r | IE | r |
| O2’ bis | −5.65 | 2.08 | −6.00 | 1.96 |
| O2’ lp 0 | −2.47 | 5.87 | −2.77 | 6.18 |
| O2’ lp 180 | −6.61 | 2.08 | −7.23 | 1.93 |
| Avg. Diff. | −0.42 | 0.01 | ||
| Abs. Avg. Diff. | 0.42 | 0.20 | ||
| O3’ (230°) | IE | r | IE | r |
| O2’ bis | −8.68 | 1.95 | −8.14 | 1.86 |
| O2’ lp 0 | −6.32 | 2.09 | −6.29 | 1.99 |
| O2’ lp 180 | −2.47 | 3.84 | −3.24 | 4.05 |
| Avg. Diff. | −0.07 | 0.01 | ||
| Abs. Avg. Diff. | 0.45 | 0.13 | ||
| O4’ (305°) | IE | r | IE | r |
| O2’ bis | −3.16 | 3.25 | −3.29 | 4.01 |
| O2’ lp 0 | −8.94 | 1.97 | −8.67 | 1.84 |
| Avg. Diff. | 0.07 | 0.32 | ||
| Abs. Avg. Diff. | 0.20 | 0.44 | ||
| Avg. Diff. (all) | −0.11 | 0.03 | ||
| Abs. Avg. Diff. (all) | 0.50 | 0.21 | ||
| RMSD (all) | 0.59 | 0.28 | ||