Basis set dependence of 1H–X spin–spin coupling constants in non-empirical pure DFT framework, X = 1H, 13C, 19F, 35Cl: Case of CHCl=CH–CF3 stereoisomers

Olivier Holtomo,Ousmanou Motapon,Mama Nsangou

doi:10.1063/5.0043005

Abstract

A collection of indirect spin–spin coupling constants (SSCCs) including 3J(H,H), nJ(C,H) (n = 1–3), nJ(H,F) (n = 3, 4), and nJ(H,Cl) (n = 2, 3) were assessed in the non-empirical density functional theory (DFT) framework for the stereoisomers of CHCl=CH–CF3. The present paper puts on view the DFT method, the basis set, and the stereoisomer dependences of the SSCCs. The basis sets cc-pVXZ and aug-cc-pVXZ (X = D, T, Q, and 5) were used to handle these nuclear parameters. The DFT scheme through the non-empirical exchange–correlation functionals Perdew–Burke–Ernzerhof, Perdew–Kurth–Zupan–Blaha exchange–correlation functional, Tao, Perdew, Staroverov, and Scuseria (PBEPBE, PKZBPKZB, and TPSSTPSS) was benchmarked by the computationally expensive second-order polarization propagator approximation method to provide a very good correlation of the nuclear SSCC parameters. This method was corrected by the relativistic, vibrational, and solvent effects. The findings show that the SSCCs are highly sensitive to the basis set. The convergence of SSCCs to the basis set limit is achieved for some coupling constants and tends to achieve for the others, except for 2J(H,Cl) and 3J(H,Cl). The functionals PBEPBE and PKZBPKZB appear as the excellent deal to assess all the coupling constants of this study. nJ(H,F) (n = 3, 4) and nJ(H,Cl) (n = 2, 3) are very well described by all the three competitive functionals and the different quality X of the basis set in regard to the experimental results and the reference values.

Highlights

The nuclear spin–spin coupling constants (SSCCs) of 1H–X (X = 1H, 13C, 19F, and 35Cl) have been experimentally measured and computed using quantum chemical methods by different groups of authors in different molecules.1–29 with regard to the SSCCs 3J(H,H) and nJ(C,H) (n = 1–3), we can mention the work done by Helgaker et al in 2000,1 where they investigated the SSCCs 1J(C,H), 2J(C,H), and 1J(C,C) in light molecules (CH4, C2H2, and C2H4) using ab initio and density functional theory (DFT) methods.They found that B3LYP rivals the time consuming methods CCSD and second-order polarization propagator approximation (SOPPA)(CCSD) combined with Huzinaga basis set HIII
We proceed by discussing each type of coupling constant for each isomer, by comparing the calculated spin–spin coupling constants at non-empirical DFT/(aug-)cc-pVXZ (X = D, T, Q, and 5) to the reference values assessed by the SOPPA method
The benchmark values for the 1H–1H, 1H–13C, and 1H–35Cl coupling constants were taken from the results of SOPPA/cc-pVTZ as it usually yields accurate results, while the benchmarks of the SSCCs 1H–19F were taken from SOPPA/cc-pVTZ, with the basis set ccpVDZ assigned to atoms H and C as they compare well with the experimental results (Table II)

Summary

INTRODUCTION

The Dunning basis set dependence of the SSCC calculations 3J(H,H), nJ(C,H) (n = 1–3), nJ(H,F) (n = 3, 4), and nJ(H,Cl) (n = 2, 3) in the cis- and trans-CHCl=CH–CF3 stereoisomers within the DFT framework was investigated These compounds are the novel refrigerant intended for use in mobile air-conditioning and refrigerators. Their UV–vis and IR spectroscopies have been intensively studied to identify the structures and to find out the radiative forcing efficiency and the global warming potential parameters for atmospheric interest Their nuclear magnetic resonance (NMR) spectroscopies are unknown, except in the work done by Schmidt et al., where they measured the coupling constants of vicinal and long-range H–F coupling constants 3J(H,F) and 4J(H,F), respectively, in the trans-CHCl=CH–CF3 stereoisomer. The convergences of the SSCCs at non-empirical DFT as a function of the basis set are discussed for each stereoisomer

Nuclear spin–spin coupling constant theory

Computational details

RESULTS AND DISCUSSIONS

SUMMARY