Effect of Hydrogen Bonding to Water on the31P Chemical Shift Tensor of Phenyl- and Trialkylphosphine Oxides and α-Amino Phosphonates

Abstract

The effect of hydrogen bonding to water on the 31P NMR chemical shift tensor in the titled compounds has been studied experimentally and simulated theoretically using the DFT-GIAO approach. It has been shown that the effect of hydrogen bonding on the 31P NMR parameters of trialkylphosphine oxides can be simulated at the GIAO-B3LYP/cc-pVDZ approximation. The influence of molecular conformation on the NMR parameters is small in these compounds. In contrast, the effect of molecular conformation can totally mask the effect of hydrogen bonding in the case of phenylphosphine oxides. The limiting case is a hydrogen bond with water. In these compounds the DFT-GIAO approach can be useful for the analysis of stronger hydrogen bonds only. The GIAO-B3LYP/cc-pVDZ approximation fails to reproduce the 31P NMR parameters of α-amino phosphonates. Thus, a combination of 31P NMR and low-cost calculations can be used especially effectively in the study of noncovalent interactions in polycrystalline and noncrystalline materials based on trialkylphosphine oxides. The described research strategy is applicable to the study of the local chemical structures in amorphous materials, at surfaces, and in interfaces.