Derivation of correlation functions to predict bond properties of phenyl-CH bonds based on vibrational and (1)H NMR...

The study of electron density properties significantly contributes to the determination of important chemical relations. The experimental determination of the electron density distribution is limited to single crystals. However, equivalent information is often desired for molecules, which do not crystallize in a sufficient manner. Furthermore, it is of high impact to study changes in the electron density distribution (i.e., related reactivities) upon environmental variations. Consequently, here we investigate methods to derive electron density properties from spectroscopic data. In particular correlation functions are introduced, which are able to predict electron density properties in all five CH-bonds of monosubstituted benzene derivatives at once. The prediction performance for electron densities and the corresponding Laplacians is lower as compared to previously introduced local functions [Presselt et al. J. Phys. Chem. A 2009, 113, 3210], but far less spectroscopic input data are needed. However, for ellipticities a higher prediction performance than this obtained for the previously derived local functions could be obtained despite the fact that less spectroscopic data were used. Thus, ellipticities are best predicted using (1)H NMR data for the para position of monosubstituted benzene derivatives.