Study of potassium O,O'-Dibutyldithiophosphate combining DFT, 31P CP/MAS NMR and infrared spectroscopy.

Dithiophosphates are used in many different industrial applications. To explain their functions and properties in these applications, a fundamental understanding on a molecular level is needed. Potassium 0,0'-Dibutyldithiophosphate and its anion have been investigated by means of a combination of DFT and 31 P CP/MAS NMR and infrared spectroscopy. Several low-energy conformations were studied by DFT. Three different conformations with significantly different torsion angles of the 0-C bond relative to the O-P-O plane were selected for further studies of infrared frequencies and 31 P NMR chemical-shift tensors. A good agreement between theoretical and experimental results was obtained, especially when the IR spectra or 31 P chemical shift tensor parameters of all three conformations were added, indicating that, because of the low energy difference between the conformations, the molecules are rapidly fluctuating between them.