Table 2. Calculated (TPSS-D3/def2-TZVP) natural charges a of the anionic CH2 groups and the boron atom in some anions of carbon acids R–CH3. Gibbs energy ΔG solv of solvation of anions and neutral CH acids were obtained with COSMO.
| (R–CH2 –) R = | q(CH2) | q(B) | q(B CH2) | Calc. pK a (CH2Cl2) | ΔG solv (anion, CH2Cl2) [kcal mol–1] | ΔG solv (acid, CH2Cl2) [kcal mol–1] |
| (C6F5)2B | –0.407 | +0.268 | –0.139 | 16.2 | –33.4 | –3.4 |
| (Mes)2B | –0.530 | +0.343 | –0.187 | 27.8 | –38.1 | –3.7 |
| 9-BBN | –0.649 | +0.422 | –0.227 | 32.4 | –42.7 | –0.8 |
| Ph | –0.367 | — | (–0.367) | 41.1 | –46.9 | –2.3 |
aSee ref. 7g.