Table 2. Calculated proton affinities, PA, [kcal mol–1], gas-phase basicities, GPB, [kcal mol–1], HOMO energies [eV] and selected NPA charges, e, [E–] of M-1–M-3 (M = Li, Na, K), 1––3– , [M-1 – H]+–[M-3 – H]+, 1, 2-H and 3-H.
| Comp. | E HOMO | e (M+) | e (E–) | Δe (E–) a | GPB c | PA d | Comp. | e (M+) | e (E) |
| 1– | –1.439 | — | –2.188 | –0.422 e | –350.2 | –351.7 | 1 | — | –1.766 |
| K-1 | –4.256 | +0.949 | –2.189 | –0.420 | –280.6 | –289.2 | [K-1 – H]+ | +0.953 | –1.769 |
| Na-1 | –4.335 | +0.917 | –2.168 | –0.399 | –282.3 | –290.7 | [Na-1 – H]+ | +0.918 | –1.769 |
| Li-1 b | –4.415 | +0.899 | –2.187 | –0.413 | –282.7 | –291.9 | [Li-1 – H]+ | +0.896 | –1.774 |
| 2– | –1.111 | — | –0.807 | –0.601 f | –339.7 | –351.6 | 2-H | — | –0.206 |
| K-2 | –3.837 | +0.945 | –0.738 | –0.567 | –278.9 | –286.3 | [K-2 – H]+ | +0.950 | –0.171 |
| Na-2 | –4.013 | +0.913 | –0.709 | –0.556 | –276.3 | –283.8 | [Na-1 – H]+ | +0.917 | –0.153 |
| Li-2 | –4.200 | +0.891 | –0.683 | –0.544 | –274.0 | –281.4 | [Li-2 – H]+ | +0.898 | –0.139 |
| 3– | –1.202 | — | –0.770 | –0.550 g | –334.9 | –344.3 | 3-H | — | –0.220 |
| K-3 | –3.914 | +0.945 | –0.698 | –0.519 | –272.7 | –280.5 | [K-3 – H]+ | +0.949 | –0.179 |
| Na-3 | –4.082 | +0.912 | –0.665 | –0.507 | –269.1 | –277.8 | [Na-3 – H]+ | +0.917 | –0.158 |
| Li-3 | –4.260 | +0.890 | –0.634 | –0.493 | –267.5 | –276.4 | [Li-3 – H]+ | +0.899 | –0.141 |
a Δe (E–) = e (E–) (base) – e (E) (conjugated acid).
b Values for Li-1 are Boltzmann averaged.
c G (H+) = –6.28 kcal mol–1, taken from ref. 12.
d H (H+) = 1.48 kcal mol–1, taken from ref. 12.
e From e (E–) (1– -A) – e (E) (1-A).
f From e (E–) (2– -A) – e (E) (2-H-A).
g From e (E–) (3– -A) – e (E) (3-H-A).