Correlation Between Experimental and DFT/GIAO Computed 13C NMR Chemical Shifts of Organic Compounds. Effects of Asymmetry

The experimental 13 C chemical shifts of five different series of organic compounds are compared with pre- dicted 13 C NMR chemical shifts obtained via empirically scaled GIAO shieldings. Our results indicate that the inclusion of a scaling factor allow to obtain an excellent correlation between δcalc and δexp. Although the inclusion of asymmetry im- proves this correlation, such enhancement was not observed for all the 54 tested compounds. We found RMS, a parameter related with the structural feature of the whole molecule, which could indicate the benefits of including asymmetry in these calculations.