¹H/¹³C chemical shift calculations for biaryls: DFT approaches to geometry optimization

Abstract

Twelve common density functional methods and seven basis sets for geometry optimization were evaluated on the accuracy of 1 H/ 13 C NMR chemical shift calculations for biaryls. For these functionals, 1 H shifts calculations for gas phase optimized geometries were significantly less accurate than those for in-solution optimized structures, while 13 C results were not strongly influenced by geometry optimization methods and solvent effects. B3LYP, B3PW91, mPW1PW91 and ω B97XD were the best-performing functionals with lowest errors; among seven basis sets, DGDZVP2 and 6-31G(d,p) outperformed the others. The combination of these functionals and basis sets resulted in high accuracy with CMAE min = 0.0327 ppm (0.76%) and 0.888 ppm (0.58%) for 1 H and 13 C, respectively. The selected functionals and basis set were validated when consistently producing optimized structures with high accuracy results for 1 H and 13 C chemical shift calculations of two other biaryls. This study highly recommends the IEFPCM/B3LYP, B3PW91, mPW1PW91 or ω B97XD/DGDZVP2 or 6-31G(d,p) level of theory for the geometry optimization step, especially the solvent incorporation, which would lead to high accuracy 1 H/ 13 C calculation. This work would assist in the fully structural assignments of biaryls and provide insights into in-solution biaryl conformations.

High-Spin S = 3/2 Ground-State Aminyl Triradicals: Toward High-Spin Oligo-Aza Nanographenes

“…The correlation between computed chemical shifts and δ expt is further illustrated by the difference plots of the scaled and experimental NMR chemical shifts (δ scaled – δ expt ) for all carbon or hydrogen atoms in the triamines (Figures S49–S52, SI). These plots confirm our structure assignments by the low values of statistical error parameters for 13 C and 1 H (with the NH groups excluded) NMR chemical shifts (Table S24, SI). − …”

Impacts of basis sets, solvent models, and NMR methods on the accuracy of 1H and 13C chemical shift calculations for biaryls: a DFT study

“…In our continuing interest in the NMR modeling of biaryls, we have recently reported the impact of density functional methods on the accuracy of 1 H/ 13 C chemical shift calculations for biaryls. 5,9 Herein, the present study shows how basis sets, solvent models, and NMR methods influence the accuracy of 1 H and 13 C NMR shift calculations for biaryl 1 (Figure 1B).…”

“…Biaryls are important core structures present in useful chiral ligands, organocatalysts, biologically active natural products, and biopolymer lignins. 1,2 Typical examples illustrated in Figure 1A are C 2 -symmetric binaphthyls (BINOL and BINAPs), which catalyze numerous asymmetric transformations 3,4 the mycotoxin viriditoxin 5 the alkaloid bismurrayaquinone A 6 and 5-5/4-O-lignin substructures 7 . These compounds also possess biaryl linkages, which can give rise to atropisomers that have received significant attention from the synthetic community in the last decade.…”

Icing mitigation through quantum sensing

“…There are several types of functional one could pick from, albeit non-systemically improbable, to fit the type of simulation. For example, we employed the hybrid PBEPBE functional because it has been shown to give a good description of the NMR spectrum [5,6]. Taking advantage of DFT functional theory utilizing the electron density approach instead of the time-consuming wavefunction-based approaches, gaussian type basis sets (GTO) are used here.…”

“…Usually, the fourth term is rewritten as 𝑞𝐸 𝑉𝐵𝑀 + 𝑞𝐸 𝐹 so that the Fermi level is set to zero at the valence band maximum 𝐸 𝑉𝐵𝑀 . The last term 𝐸 corr is to correct the error due to the finite size (6) Figure 1. A.)…”