NMR and theoretical study on the structure of O,O-dimethyl-1,4-oxoazetin-2-ylphosphonate

The changes in NMR spectra of O,O-dimethyl-1,4-oxoazetin-2-ylphosphonate (DMOAP) in polar and non-polar solvents were studied by means of experimental and theoretical approach. The precise chemical shift assignments of DMOAP were obtained by means of 1H, 1H{31P}, 13C{1H}, 31P{H} NMR and theoretical calculations (DTF, using the IGLO II and IGLO III basis set and solvent model PCM for CHCl3, MeOH, H2O). An optimized structure, calculated using B3LYP/6-31G(d, p) solvent model PCM, gives three conformers in their energetic minima with various values of NCPO angle. Distribution of particular conformers, their structural differences and effect of internal or external hydrogen bonds in polar and non-polar solvents were considered as potential causes of the observed diversities in NMR spectra.