Toward the comprehensive calculations on the relationship between ¹H, ¹³C, ³¹P chemical shifts, ²J_PH, and the bonding structure of different phosphoryl benzamides

Abstract

A comprehensive investigation was performed on 1H, 13C, and 31P nuclear magnetic resonance (NMR) chemical shifts (CSs) of phosphoryl benzamide derivatives (C6H5C(O)NHP(O)R1R2), (R1, R2 = aziridine [L1], azetidine [L2], pyrrolidine [L3], piperidine [L4], azepane [L5], 4‐methylpiperidine [L6], propane‐2‐amine [L7], and 2‐methylpropane‐2‐amine [L8]) by the gauge‐independent atomic orbital method (GIAO) to find the most accordant level of theory with the experimental values. To achieve this goal, all the structures were optimized using the B3LYP, BP86, PBE1PBE, M06‐2X, MPWB1K, and MP2 methods with 6–31+G* basis set. Computed structural parameters demonstrate that BP86 has the best agreement to the experimental values between the other methods. The def2‐TZVP and aug‐cc‐pVDZ basis sets were also employed to inspect the effect of different types of basis sets with higher polarization and diffuse functions. The correlation between the empirical and computational values attests that 6–31+G* basis set is the optimum case regarding minimization of the costs and results. The comparison between calculated and experimental CSs at all mentioned combinations illustrated that in accordance with structural results, the best level of theory in CSs is also BP86/6–31+G*. Besides, 2JPH values were computed with an acceptable agreement to experimental data at the optimum level of theory. The dependency between 2JPH and the bonding structure of studied ligands was also scrutinized by the Natural Bond Orbital (NBO) analysis that interprets the relationship between the electronic properties and 2JPH values.

Recent advances in computational 31P NMR: Part 2. Spin–spin coupling constants

“…Very recently, Gholivand et al performed DFT calculation of 2 J PC coupling constants in the series of phosphoryl benzamides, C 6 H 5 C(O)NHP(O)R 1 R 2 , with R 1 and R 2 being aziridine, azetidine, pyrrolidine, piperidine, azepane, 4‐methylpiperidine, propane‐2‐amine, and 2‐methylpropane‐2‐amine. Calculated 2 J PC couplings were in a reasonably good agreement with available experimental data, and their substituent trends were interpreted in terms of geometric and electronic properties, the latter involving atomic charge and hybridization effects on phosphorous.…”

Caveats and Perspectives of Computational Phosphorous Nmr: Spin-Spin Coupling Constants

“…Very recently Gholivand, et al [38] performed DFT calculation of 2 J PC coupling constants in the series of phosphoryl benzamides, C 6 H 5 C(O)NHP(O)R 1 R 2 , with R 1 and R 2 being aziridine, azetidine, pyrrolidine, piperidine, azepane, 4-methylpiperidine, propane-2-amine, and 2-methylpropane-2-amine. Calculated 2 J PC couplings were in a reasonably good agreement with available experimental data, and their substituent trends were interpreted in terms of geometric and electronic properties, the latter involving atomic charge and hybridization effects on phosphorous.…”