Solid state and solution study of some phosphoramidate derivatives containing the P(O)NHC(O) bifunctional group: Crystal structures of CCl2HC(O)NHP(O)(NCH3(CH2C6H5))2, p-ClC6H4C(O)NHP(O)(NCH3(CH2C6H5))2, CCl2HC(O)NHP(O)(N(CH2C6H5)2)2 and p-BrC6H4C(O)NHP(O)(N(CH2C6H5)2)2

Synthetic methods for several novel phosphoramidate compounds containing the P(O)NHC(O) bifunctional group were developed. These compounds with the general formula R1C(O)NHP(O)(N(R-2)(CH2C6H5))(2), where R-1 = CCl2H, p-ClC6H4, p-BrC6H4, o-FC6H4 and R-2 = hydrogen, methyl, benzyl, were characterized by several spectroscopic methods and analytical techniques. The effects of phosphorus substituents on the rotation rate around the P-N-amine bond were also investigated. H-1 NMR study of the synthesized compounds demonstrated that the presence of bulky groups attached to the phosphorus center and electron withdrawing groups in the amide moiety lead to large chemical-shift non-equivalence (Delta delta(H)) of diastereotopic methylene protons. The crystal structures of CCl2HC(O)NHP(O)(NCH3(CH2C6H5))(2). p-ClC6H4C(O)NHP(O)(NCH3(CH2C6H5))(2), CCl2HC(O)NHP(O)(N(CH2C6H5)(2))(2) and p-BrC6H4C(O)NHP(O)(N(CH2C6H5)(2))(2) were determined by X-ray crystallography using single crystals. The coordination around the phosphorus center in these compounds is best described as distorted tetrahedral and the P(O) and C(O) groups are anti with respect to each other. In the compound Br-C6H4C(O)NHP(O)(N(CH2C6H5)(2))(2) (with two independent molecules in the unit cell), two conformers are connected to each other via two different N-H center dot center dot center dot O hydrogen bonds forming a non-centrosymmetric dimer. In the crystalline lattice of other compounds, the molecules form centrosymmetric dimers via pairs of same N-H center dot center dot center dot O hydrogen bonds. The structure of CCl2HC(O)NHP(O)(N(CH2C6H5)(2))(2) reveals an unusual intramolecular interaction between the oxygen of C=O group and amine nitrogen. (C) 2010 Elsevier B.V. All rights reserved.