Dependence of the long-range phosphorus-hydrogen coupling constant nJP-H(n=3, 6, 7) on the bond order between phosphorus and its substituents:: preparation and spectroscopic characterization of several phosphoramidates

The examination of spectra of a selected series of phosphoramidates showed that, in addition to a double bond, whenever there are one or two partial multiple bonds in the molecule the long-range coupling constant, such as (6)J(P-H), (7)J(P-H) and (3)J(P-H), either disappears or at least reduces. In particular, the experimental data indicate the unexpected effect of a partial multiple bond between phosphorus and fluorine in (7)J(P-H) and (3)J(P-H). The preparation of the compounds p-CH3C6H4NHP(O)Cl-2 (II), p-CH3C6H4NHP(O)(Cl)OC6H4CH3-p (XIV), m-CH3C6H4NHP(O)(Cl)OC6H4CH3-p (XV), m-CH3C6H4NHP(O)(Cl)OC6H4CH3-m (XVI) and the rigid molecule CH3C6H3(NH)(2)P(O)Cl (XVII) are described and they are characterized by H-1, C-13, P-31 NMR, IR spectroscopy and elemental analysis. Copyright (C) 2001 John Wiley & Sons, Ltd.