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[dbnd]CH2)2. In compound 3, there are intermolecular -P[dbnd]O … H-N- and -C[dbnd]O … H-N- hydrogen bonds which form a one-dimensional polymeric chain. Compound 7 contains intermolecular -P[dbnd]O … H-N- hydrogen bonds leading to a one-dimensional polymeric chain. Compound 36 forms intermolecular -P[dbnd]O … H-N-, -C[dbnd]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-Namine bond lengths in 3 relative to 6 cause a greater ΔG# value in 3.
Acknowledgments
The financial support of this work by Research Council of Tarbiat Modares University is gratefully acknowledged.