On the calculation of 15N chemical shifts using linear regression formulae. A performance comparison of different methods was written by Franca, Carlos A.;Pis Diez, Reinaldo;Jubert, Alicia H.. And the article was included in Journal of Molecular Structure: THEOCHEM in 2008.Computed Properties of C8H11N This article mentions the following:
The calculation of NMR chem. shifts using linear regression formulas is revisited 15N chem. shifts are considered as a test case. Mean unsigned errors of 4.8, 5.4 and 7.6 ppm are found for the B3LYP/6-31G(d)//B3LYP/6-31G(d), B3LYP/6-311+G(2d,p)//B3LYP/6-31G(d) and HF/6-31G(d)//B3LYP/6-31G(d) levels of theory, resp., which are much more accurate than chem. shifts calculated by subtracting theor. magnetic isotropic shieldings from the reference nitromethane. Also, the economical HF/6-31G(d)//B3LYP/6-31G(d) method is ∼15 times faster than the rather expensive B3LYP/6-311+G(2d,p)//B3LYP/6-31G(d) level of theory but only 2.5 times faster than B3LYP/6-31G(d)//B3LYP/6-31G(d). The authors’ results indicate that the B3LYP/6-31G(d)//B3LYP/6-31G(d) level of theory constitutes an adequate compromise between accuracy and computational cost for 15N chem. shifts calculation using a linear regression formula. In the experiment, the researchers used many compounds, for example, 2-Isopropylpyridine (cas: 644-98-4Computed Properties of C8H11N).
2-Isopropylpyridine (cas: 644-98-4) belongs to pyridine derivatives. Pyridine has a conjugated system of six π electrons that are delocalized over the ring. The molecule is planar and, thus, follows the Hückel criteria for aromatic systems. Reduced pyridines, namely tetrahydropyridines, dihydropyridines and piperidines, are found in numerous natural and synthetic compounds. The synthesis and reactivity of these compounds have often been driven by the fact many of these compounds have interesting and unique pharmacological properties. Computed Properties of C8H11N