Synthesis and structural study of five new phosphoric triamides: interplay between classical and non-classical intermolecular interactions

Abstract Phosphoric triamides are attractive to investigate because of their extensive applications in various fields, especially in medicine. Five new phosphoric triamides with the main parts [N]P(O)[NH]2 and [C(O)NH]P(O)[N]2 have been structurally analyzed by single crystal MoKα/synchrotron-based X-ray diffraction and characterized by spectroscopic methods (FT-IR and 1H, 13C, 31P NMR). Compounds crystallize in orthorhombic (1 with space group Pnma) and monoclinic (2 (P21/a), 3 (C2/c), 4 (P21/n) and 5 (P21/c)) crystal systems. The asymmetric unit of all structures consists of one phosphoric triamide molecule, except for 1 with one half of molecule. X-ray crystallography data reveal that the molecular architectures constructed by classical N—H … O hydrogen bonds are as 1D linear (building the R21(6)${R}\_{2}^{1}(6)$, C(4) and R22(10)/R21(6)${R}\_{2}^{2}(10)/{R}\_{2}^{1}(6)$ motifs, respectively, for 1–3) or dimeric (the R22(8)${R}\_{2}^{2}(8)$ ring motif for 4 and 5). A detailed investigation of the intermolecular interactions using Hirshfeld surface (HS) analysis illustrates that the H … H, O … H/H … O and C … H/H … C contacts for all compounds, and Cl … H/H … Cl and F … H/H … F contacts for 3–5, are the most significant contributors to the crystal packing. Moreover, based on the calculated enrichment ratios (E), the O … H/H … O contacts including the classical N—H … O hydrogen bonds for all structures are considered as favoured contacts.