N⋯H–N and O⋯H–N NBO second-order perturbation energies E(2) (in kcal mol−1) and electron density (ρ) at the bcp and its Laplacian (∇2ρ) in parenthesis computed at ωB97XD/6-31+G(d,p).
| Isomers | H Charge transfer | NBO E(2) | ρ(∇2ρ) |
|---|---|---|---|
|
O12(LP) → N7–H22(σ*) | 5.66 | 0.020(−0.018) |
| O12(LP) → N5–H16(σ*) | 3.92 | 0.017(−0.016) | |
| O11(LP) → N2–H8(σ*) | 2.51 | 0.016(−0.016) | |
| O11(LP) → N4–H15(σ*) | 3.10 | 0.019(−0.018) | |
| Total E(2) | 15.19 | ||
|
O21(LP) → N19–H12(σ*) | 7.96 | 0.024(−0.018) |
| O21(LP) → N7–H20(σ*) | 7.06 | 0.022(−0.018) | |
| O24(LP) → N16–H4(σ*) | 0.99 | — | |
| O24(LP) → N17–H14(σ*) | 1.23 | — | |
| Total E(2) | 17.24 | ||
|
N22(LP) → N6–H10(σ *) | 7.74 | 0.022(−0.018) |
| O23(LP) → N5–H7(σ*) | 1.24 | — | |
| O23(LP) → N3–H13(σ*) | 1.51 | — | |
| Total E(2) | 10.49 |