Theoretical Modeling of 13C NMR Chemical Shifts— How to Use the Calculation Results
AbstractOwing to wide accessibility of the general utility quantum chemistry programs, theoretical calculations of spectral parameters defining NMR spectra have become relatively easy for medium size molecules. This new and powerful tool allows investigators to perform much deeper interpretation of the NMR data and gain new information valuable for structural chemistry studies. It is usually realized and well understood that theoretical calculations of NMR parameters, as for any quantum mechanical calculations, have several limitations, difficult to overcome, and that the accuracy of calculation results is strongly dependent on the theoretical method applied. On the other hand, it is less commonly recognized that the effectiveness of all the combined calculational/spectroscopic approach depends meaningfully on the method of comparison of the experimental and theoretical data as well. This article is addressed primarily to experimental chemists who use in their everyday work 13C NMR spectroscopy to solve various structural and physicochemical problems. After recalling some basic concepts concerning NMR parameters and their calculations, some suggestions concerning the rational choice of the calculational method and the experiment/theory comparison method are formulated. To support these recommendations and convince the reader of their utility, several practical examples are presented in the text. All these concepts reflect the author’s beliefs which, albeit well-grounded, by no means should be treated as indispensable truths; they are rather worth considering as hints about how to solve various practical dilemmas.
|Journal series||Concepts in Magnetic Resonance Part A, ISSN 1546-6086|
|Keywords in English||13C NMR; chemical shifts; shielding constants; DFT; correlation analysis|
|Publication indicators||: 2011 = 1.674 (2) - 2011=1.42 (5)|
|Citation count*||9 (2015-02-15)|
* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.