Table 6. Experimental Hydrogen Bond Induced Δν(OH)exp shifts (cm–1) vs Atomic Charges at the Carbonyl Oxygen of the Monomer Esters (in Electrons)a,b for a Series of Substituted Alkyl Benzoates.
| molecule | qO(Hirsh) | qO(CM5) | qNPAOqO(NPA) | Δν(OH)exp |
|---|---|---|---|---|
| ethyl benzoate | –0.2919 | –0.3420 | –0.6368 | 81 |
| ethyl 4-methylbenzoate | –0.2949 | –0.3450 | –0.6402 | 85 |
| ethyl 3-methylbenzoate | –0.2928 | –0.3431 | –0.6384 | 83 |
| ethyl 4-methoxybenzoate | –0.2982 | –0.3482 | –0.6446 | 88 |
| ethyl 4-(dimethylamino)benzoate | –0.3065 | –0.3562 | –0.6546 | 106 |
| ethyl 4-fluorobenzoate | –0.2920 | –0.3422 | –0.6374 | 76 |
| ethyl 3-fluorobenzoate | –0.2876 | –0.3377 | –0.6310 | 74 |
| ethyl 4-(trifluoromethyl)benzoate | –0.2851 | –0.3353 | –0.6285 | 67 |
| ethyl 4-bromobenzoate | –0.2890 | –0.3392 | –0.6333 | 72 |
| ethyl 4-cyanobenzoate | –0.2827 | –0.3329 | –0.6254 | 60 |
| diethyl terephthalate | –0.2872 | –0.3374 | –0.6306 | 69 |
| ethyl 4-nitrobenzoate | –0.2809 | –0.3312 | –0.6232 | 57 |
| methyl benzoate | –0.2901 | –0.3402 | –0.6351 | 76 |
| methyl 4-methylbenzoate | –0.2933 | –0.3432 | –0.6386 | 80 |
| methyl 4-methoxybenzoate | –0.2976 | –0.3475 | –0.6444 | 90 |
| methyl 4-(dimethylamino)benzoate | –0.3051 | –0.3548 | –0.6532 | 107 |
| methyl 4-fluorobenzoate | –0.2903 | –0.3403 | –0.6358 | 78 |
| methyl 4-chlorobenzoate | –0.2878 | –0.3378 | –0.6323 | 74 |
| methyl 4-bromobenzoate | –0.2873 | –0.3373 | –0.6316 | 74 |
| methyl 4-cyanobenzoate | –0.2808 | –0.3309 | –0.6235 | 60 |
| methyl 4-nitrobenzoate | –0.2792 | –0.3294 | –0.6214 | 58 |
| correlation coefficient, rb | 0.988 | 0.987 | 0.989 |
a
Atomic charges evaluated using the Hirshfeld, CM5 and NPA methods from ωB97X-D/6-311++G(3df,2pd) density functional theory computations (for references to the theoretical methods employed and the experimental Δν(OH)exp shifts in CCl4 solvent see ref (22)).
b
Absolute values of correlation coefficients.