Influence of Density Functionals and Basis Sets on One-Bond Carbon−Carbon NMR Spin−Spin Coupling Constants

Abstract

The basis set and the functional dependence of one-bond carbon-carbon NMR spin-spin coupling constants (SSCC) have been analyzed using density functional theory. Four basis sets (6-311G**, TZVP, EPR-III, and aug-cc-pVTZ-J) and four functionals (PBE, PW91, B3LYP, and B3P86) are tested by comparison with 70 experimental values corresponding to 49 molecules that represent multiple types of hybridization of the carbon atoms. The two hybrid functionals B3P86 and B3LYP combined either EPR-III or aug-cc-pVTZ-J basis sets lead to the best accuracy of calculated SSCC. However, a simple linear regression allows for the obtaining of scaled coupling constants that fit much better with the experimental data and where the differences between the different basis sets and/or functional results are significantly reduced. For large molecules the TZVP basis set can be an appropriate election presenting a good compromise between quality of results and computational cost.

H2O, H2, HF, F2 and F2O nuclear magnetic shielding constants and indirect nuclear spin–spin coupling constants (SSCCs) in the BHandH/pcJ‐n and BHandH/XZP Kohn–Sham limits

“…CBS estimated BHandH equilibrium proton and oxygen nuclear isotropic shieldings of water (in ppm) calculated using GIAO method and XZP, pcS-n and pcJ-n basis sets too erratic and are omitted from fittings. [11,24,26] The extrapolated lines (3-parameter exponential fits) indicate practically identical performance of the three basis set families in the basis set limit, and there are only minor differences in 17 O isotropic shielding sensitivity to the basis set type (XZP > pcS-n > pcJ-n).…”

“…Recently established experimental 17 O isotropic shielding of gaseous water is 323.6 ppm [58] and the rovibrational and temperature corrections, taken directly from Ref. [59] is −10.93 ppm, which makes the empirical equilibrium experimental value of 334.53 ppm.…”

“…On the other hand, DFT provides a relatively inexpensive alternative for predicting NMR parameters [16] in larger molecules. Recently, Suardiaz et al [17] concluded that B3LYP combined with EPR-III [18,19] or aug-cc-pVTZ-J [20 -22] basis sets lead to the best one bond carbon-carbon spin-spin coupling constants of 49 studied molecules.…”

Communication: Accurate determination of side-chain torsion angle χ1 in proteins: Phenylalanine residues

“…This fact has been recently interpreted as a consequence of hyperconjugative interactions between orbitals of the coupling pathway and those of carbonyl group. 8,23,24 It is also noteworthy that the value of coefficient S 2 is larger than those of S 1 and C 3 (extra coefficient regarding classic Karplus equation) suggesting a more important role in the fitting of truncated Fourier series.…”

“…B3LYP/TZVP level of theory has proved to provide similar results to those of ab initio SOPPA and SOPPA(CCSD) methods with larger basis sets 19 and has been used successfully in the calculations of J and hyperfine couplings. [20][21][22][23][24] (5) The nine sets of coupling constants 3 J XY and the angles from geometry optimizations were used to calculate the six corresponding Fourier coefficients in Eq. (1), solving 6 × 6 system of nonhomogeneous linear equations.…”