Synthesis, X-ray Diffraction Studies, and Hydrogen Bonding Analysis of a New Phosphoramide Counterion in Solid State

Abstract

In the present study, we report the structure of one new phosphoramidate counter ion. The single crystal X-ray diffraction analysis revealed that C₁₈H₁₈N₃O₄P₁, consists of a discrete [C₁₈H₁₈N₂OP]⁺ cation and NO₃⁻ anion. The compound crystallizes in triclinic system, space group P-1, unit cell a = 9.4935 Å, b = 10.4556(4) Å, c = 11.1560(3) Å, α = 63.951(3)°, β = 67.039(3)°, γ = 66.017(3)°. The interaction between cation and anion has occurred through hydrogen bonding. The strength of different hydrogen bonds between two counter ions was studied by DFT calculations in the gas phase. We optimized the hydrogen atoms and kept all other atoms invariant in the optimization process. The H-optimized systems included one nitrate anion and one phosphoramide cation which were connected by special intermolecular interactions. The binding energies of these interactions were calculated (M062X/6-311G*) and corrected for the basis set superposition error (BSSE) using by counterpoise (CP) procedure. Moreover, the main noncovalent inter-molecular interactions were studied by Hirshfeld surface analysis and finger print plots.