Kostin Mikhail A, Pylaeva Svetlana A, Tolstoy Peter M
Department of Physics, St. Petersburg State University, St. Petersburg, Russia.
Chair of Theoretical Chemistry, University of Paderborn, Paderborn, Germany.
Phys Chem Chem Phys. 2022 Mar 16;24(11):7121-7133. doi: 10.1039/d1cp05939d.
In this work we evaluate the possibility of using the NMR and IR spectral properties of the PO group to estimate the geometry and strength of hydrogen bonds which it forms with OH-, NH- and CH-acids. The results of the DFT study of 70 hydrogen-bonded 1 : 1 complexes of a model trimethylphosphine oxide, MePO, with various proton donors in the gas phase and in aprotic medium (modelled as a polarizable continuum) are presented. Four types of hydrogen bonds with the general formula MePO⋯H-A were considered, where the A atom is O, C, and N (neutral or cationic acids). Within the selected set of complexes the hydrogen bond energy varies over a wide range ( 0-85 kJ mol). We show that it is possible to use simple correlations to estimate the energy and geometry of OHO, NHO and CHO hydrogen bonds from the changes of isotropic P NMR chemical shifts and harmonic PO stretching vibration frequencies upon complexation. Such correlations also could be used to estimate the proton-donating ability (and Brønsted acidity; p) of OH acids.
在这项工作中，我们评估了利用P=O基团的核磁共振（NMR）和红外（IR）光谱性质来估算其与OH-、NH-和CH-酸形成的氢键的几何结构和强度的可能性。本文给出了在气相和非质子介质（模拟为可极化连续介质）中，模型三甲基氧化膦（MePO）与各种质子供体形成的70种1:1氢键复合物的密度泛函理论（DFT）研究结果。考虑了通式为MePO⋯H-A的四种类型的氢键，其中A原子为O、C和N（中性或阳离子酸）。在所选的复合物组中，氢键能在很宽的范围内变化（0 - 85 kJ/mol）。我们表明，可以利用简单的相关性，根据络合时各向同性P NMR化学位移的变化和谐波P=O伸缩振动频率来估算O-H⋯O、N-H⋯O和C-H⋯O氢键的能量和几何结构。这种相关性也可用于估算OH酸的质子给予能力（和布朗斯特酸度；pKa）。
