Vibrational studies of N-trifluoroacetyl-phosphoramidic acid dichloride [CF3C(O)NHP(O)Cl2] and N-trichloroacetyl-phosphoramidic acid dichloride [CCl3C(O)NHP(O)Cl2]

The infrared and Raman spectra of N-trifluoroacetyl-phosphoramidic acid dichloride [CF3C(O)NHP(O)Cl2] and N-trichloroacetyl-phosphoramidic acid dichloride [CCl3C(O)NHP(O)Cl2] in the solid phase have been recorded and interpreted. Quantum chemical calculations were performed with ab initio and Density Functional Theory (DFT) methods using different levels of approximation. The vibrational spectra and theoretical calculations show a dimeric form (CF3C(O)NHP(O)Cl2) with Ci symmetry (CO double bond in anti position with respect to the PO double bond) in agreement with reported X-ray diffraction studies. Also, a dimeric form is proposed for CCl3C(O)NHP(O)Cl2. A tentative assignment of the observed bands for these molecules is discussed. 1H, 13C, 19F and 31P NMR chemical shifts are reported.