Syntheses,crystal structures and dynamic 1 H NMR study of diastereotopic CH 2 protons in several new phosphoric triamides

Abstract

Several phosphoric triamides with formula C₆H₅C(O)N(H)P(O)X₂, X = N(C₂H₅)(CH₂C₆H₅) (1), NC₄H₈ (2), NH-CH₂-C₆H₅ (3), NH-CH₂-(2-Cl-C₆H₄) (4), NH-CH₂-CH(C₂H₅)(C₄H₉) (5), N(C₂H₅)₂ (6) and P(O)(NH-CH₂-C₆H₅)₃ (7) were synthesized and characterized by ¹H, ¹³C, ³¹P NMR and IR spectroscopy and elemental analysis. The structures were determined for compounds 3, 7 and 36, 4-F-C₆H₄C(O)NHP(O)(NH-CH₂-CH=CH₂)₂. In compound 3, there are intermolecular -P=O … H-N- and -C=O … H-N- hydrogen bonds which form a one-dimensional polymeric chain. Compound 7 contains intermolecular -P=O … H-N- hydrogen bonds leading to a one-dimensional polymeric chain. Compound 36 forms intermolecular -P=O … H-N-, -C=O … H-N- and -C-F … H-N- hydrogen bonds which produce a three-dimensional polymeric chain in the crystalline network. The effects of rotation, ring inversion, temperature and solvent on the coupling patterns of the CH₂ protons in ¹H NMR spectra were discussed. The Gibbs free energy for the rotation around the P-N bond in compounds 3, 6 and 41, (4-CH₃-C₆H₄-O)P(O)Cl[N(CH₃)(CH₂C₆H₅)], were calculated from dynamic ¹H NMR spectra at low temperatures. The ΔG^# value for compound 3 is the greatest one among these molecules. The crystal structures of compounds 3 and 6 indicates that the slightly smaller P-N_amine bond lengths in 3 relative to 6 cause a greater ΔG^# value in 3.