The electronic effects of substituents on ⁿJ_PX (n = 2, 3; X = H, C) coupling constants and phosphorus chemical shifts; syntheses and spectroscopic investigation of some phosphoramidates

Abstract

New phosphoramidates with the general formulae Me₂NP(O)Cl(p-NHC₆H₄-R) (A) and Me₂NP(O)(p-NHC₆H₄-R)₂ (B), where R = H, CH₃ and NO₂, F, Cl, Br, I, were synthesized and characterized by ¹H, ¹³C, ³¹P NMR and IR spectroscopy and elemental analysis. The electronic effects of donor, acceptor and neutral groups on ⁿ J _PX coupling constants (n = 2, 3; X = H, C) and phosphorus chemical shifts are discussed. NMR data show that only the 4-nitroaniline substituent resulted in the disappearance of all coupling ( ⁿ J _PX = 0.0 Hz). Two nearly linear correlations were obtained between para-substituent constants (σ_p ) and phosphorus chemical shifts for the two series A and B.

Keywords:

• Phosphoramidates
• NMR
• Phosphorus chemical shifts
• para-Substituent constants