Structure and Intramolecular Mobility of Some Derivatives of Bis(thio)phosphorylated Amides in CCL4, CD2CL2, and CD3CN Solutions

The structure and intramolecular mobility of some derivatives of bis(thio)phosphorylated amides in CCl4, CD2Cl2, and CD3CN solutions were examined by 1H and 31P NMR spectroscopy. A comparative analysis of the temperature-dependent 1H and 31P NMR spectra of the studied compounds with symmetric and asymmetric substitution at phosphorus atoms was carried out. Various intramolecular processes were identified – rotation around C-N bonds, conformational transformations of molecules, tautomerism, and phosphorylotropic rearrangement with the formation of various conformational forms. It was shown that a dynamic equilibrium of several forms is reached, with the amide (phosphazo-) form having a clear advantage.