How reliable are Minnesota density functionals for modeling phosphorus-hydrogen NMR spin-spin coupling constants?

The Minnesota density functionals may be considered as the widely adopted of the developed functionals between the years 2005 and 2017. In this work, we present a systematic benchmark study on the accountability of several Minnesota functionals for predicting the nuclear magnetic resonance (NMR) spin-spin coupling constants (SSCCs) in diverse sets of compounds containing phosphorus-hydrogen (P-H) bonds for which experimental data were available. Although each of the Minnesota functionals has pros and cons, we find that the local (M06-L), hybrid (M06-2X), and screened exchange (MN12-SX) functionals not only give an improved description of P-H SSCCs with respect to other approximations, but also provide the results better than or comparable to those obtained using other functionals from various rungs. Furthermore, we figure out that the long-range corrected Minnesota functionals are more appropriate for the compounds with P(III), while for the molecules containing P(V) with different geometries the corresponding screened exchange versions are better choices. Perusing the role of continuum solvent versus gas phase shows that the relative rankings of the benchmarked functionals do not generally vary. All in all, the strengths and weaknesses of the Minnesota density functionals aside, hopefully such efforts can pave the way for further improvements on these approximations toward designing novel functionals for modeling various parameters in computational NMR spectroscopy.