A Multi-standard Approach for GIAO 13C NMR Calculations

SAROTTI, A.M.*; PELLEGRINET, S.C.*

JOURNAL OF ORGANIC CHEMISTRY

ACS

Año: 2009 vol. 74 p. 7254 - 7260

0022-3263

The influence of the reference standard employed in the calculation of 13C NMR chemical shifts wasinvestigated over a large variety of known organic compounds, using different quantum chemistry methodsand basis sets. After detailed analysis of the collected data, we found that methanol and benzene areexcellent reference standards for computing NMR shifts of sp3- and sp-sp2-hybridized carbon atoms,respectively. This multi-standard approach (MSTD) performs better than TMS in terms of accuracy andprecision and also displays much lower dependence on the level of theory employed. The use ofmPW1PW91/6-31G(d)//mPW1PW91/6-31G(d) level is recommended for accurate 13C NMR chemicalshift prediction at low computational cost.