Table 7. Experimental Hydrogen Bond Induced Δν(OH)exp shiftsa (cm–1), Hirshfeld, CM5 and NPA Atomic Charges (in electrons),b and Shifts of the Electrostatic Potential at the Nitrogen Atom (ΔVN, a.u.)b,c of Monomer Pyridine Derivatives.
| qN(Hirsh) | qN(CM5) | qN(NPA) | ΔVN | Δν(OH)exp | |
|---|---|---|---|---|---|
| pyridine | –0.1825 | –0.3776 | –0.4790 | 0.0000 | 286 |
| 3-fluoropyridine | –0.1700 | –0.3653 | –0.4563 | –0.0149 | 240 |
| 3-chloropyridine | –0.1691 | –0.3648 | –0.4588 | –0.0161 | 237 |
| 3-bromopyridine | –0.1687 | –0.3645 | –0.4587 | –0.0163 | 241 |
| 3-benzoylpyridine | –0.1709 | –0.3666 | –0.4697 | –0.0164 | 248 |
| 3-cyanopyridine | –0.1635 | –0.3595 | –0.4632 | –0.0323 | 203 |
| 3-ethylpyridine | –0.1845 | –0.3799 | –0.4743 | 0.0045 | 305 |
| 3-methylpyridine | –0.1842 | –0.3797 | –0.4742 | 0.0043 | 300 |
| 4-methylpyridine | –0.1904 | –0.3854 | –0.4892 | 0.0069 | 304 |
| 4-ethylpyridine | –0.1902 | –0.3852 | –0.4883 | 0.0071 | 306 |
| 4-methoxypyridine | –0.2014 | –0.3960 | –0.5098 | 0.0112 | 312 |
| 4-vinylpyridine | –0.1850 | –0.3799 | –0.4806 | 0.0019 | 293 |
| 4-acetylpyridine | –0.1697 | –0.3651 | –0.4573 | –0.0143 | 255 |
| 4-cyanopyridine | –0.1607 | –0.3563 | –0.4506 | –0.0320 | 214 |
| 4-N,N-dimethylaminopyridine | –0.2184 | –0.4121 | –0.5331 | 0.0289 | 366 |
| 4-phenylpyridine | –0.1854 | –0.3804 | –0.4812 | 0.0022 | 293 |
| 4-piperidinopyridine | –0.2200 | –0.4137 | –0.5347 | 0.0309 | 359 |
| 4-aminopyridine | –0.2122 | –0.4060 | –0.5260 | 0.0213 | 347 |
| 4-chloropyridine | –0.1786 | –0.3740 | –0.4770 | –0.0120 | 255 |
| 4-methylaminopyridine | –0.2182 | –0.4117 | –0.5344 | 0.0275 | 354 |
| 4-pyrrolidinopyridine | –0.2209 | –0.4144 | –0.5373 | 0.0317 | 373 |
| 4-tert-butylpyridine | –0.1906 | –0.3859 | –0.4864 | 0.0083 | 303 |
| 3,4-dimethylpyridine | –0.1918 | –0.3872 | –0.4839 | 0.0108 | 314 |
| 3,5-dimethylpyridine | –0.1859 | –0.3816 | –0.4698 | 0.0083 | 316 |
| 3,5-dichloropyridine | –0.1566 | –0.3529 | –0.4396 | –0.0307 | 200 |
| N-methyl-N-pyridin-4-ylhydrazine | –0.2138 | –0.4077 | –0.5271 | 0.0212 | 354 |
| 4-(4-methylpiperidino)pyridine | –0.2118 | –0.4060 | –0.5216 | 0.0242 | 359 |
| 4-N,N-diethylaminopyridine | –0.2199 | –0.4137 | –0.5344 | 0.0302 | 370 |
| methyl nicotinate | –0.1740 | –0.3693 | –0.4751 | –0.0101 | 250 |
| r (cor. coeff.)d | 0.973 | 0.974 | 0.921 | 0.994 |
a
In cm–1, from ref (21).
b
From ωB97X-D/6-311++G(3df,2pd) computations.
c
Shifts with respect the VN for unsubstituted pyridine.
d
Absolute values of correlation coefficients.