IR-SPECTRAL INVESTIGATIONS OF DIMETHYL-N-TRICHLOROACETYLAMIDOPHOSPHATE AND ITS SOME COMPOUNDS

UDC 547.022+543.421/.424

Abstract

Partially H[L‑d₆]) and full (D[L‑d₆]) deutero-substituted analogues of dimethyl-N-trichloroacetylamidophosphate (H[L]) as well as its sodium salts (Na[L]) and (Na[L‑d₆]) have been synthesized. It was shown the possibility of their interconversion excepting the direct replacement of protons of the methyl groups on deuterons. The detailed comparative analysis of IR- spectra clearly allowed ascribing of the absorption bands corresponding to N-H and C-H valence and deformation vibrations in dimethyl-N-trichloroacetylamidophosphate molecule. The shape of the absorption band N-H in the region 3068 cm^-1 (for N-D – 2262 cm^-1) demonstrates the realization of imidic structure among three of theoretically possible tautomeric forms of H[L] in solid state. In the spectra of the sodium salts the absence of these bands indicates the existence of dimethyl-N-trichloroacetylamidophosphate in the anionic form. Isotopic substitution of methyl protons leads to a significant low-frequency shift of the bands of stretching and deformation vibrations: (n_as+sC-H) 2958–2885 cm^-1, (d_as+sC-H) 1460 cm^{-1 in the spectrum of H[L] and (}n_as+sC-D) 2274–2082 сm^-1, (d_as+sC-D)
1335 сm^{-1 in the spectrum of D[L-d}₆] respectively. The low-frequency shifts (D » 60–100 сm^‑1) of characteristic n(C=O) band were observed in the spectra of onic- salts and complexes due to delocalization of p-electron density in the OCNPO – chelate fragment under deprotonation or coordination. The same tendency reveals n(P=O) band (D » 38–128 сm^‑1). The biggest low-frequency shift (128 cm^-1) was fixed for this absorption band in the spectrum of SbPh₄[L], that allowed the definition of the most preferable donor centre of dimethyl-N-trichloroacetylamidophosphate-anion [L]^- - the oxygen atom of phosphoryl group.