Synthesis and spectroscopic characterization of a new phosphoric triamide: [2,3-F2–C6H3C(O)NH]P(O)[NC5H10]2

NMR spectroscopy is the most important analytical tool for chemists who work on synthesis. In recent years, this powerful and valuable tool has been used to identify phosphoramide compounds [1-4]. In this regard, a new phosphoric triamide with formula [2,3-F2–C6H3C(O)NH]P(O)[NC5H10]2 (1, Fig. 1) was synthesized and characterized by 1H, 13C{1H}, 31P{1H} NMR and IR spectroscopy.Reaction of phosphorus pentachloride and 2,3-difluorobenzamide in dry CCl4 at 365 K (3 h) followed by treatment with formic acid at 273 K (ice water bath) leads to the formation of 2,3-F2–C6H3C(O)NHP(O)Cl2 (scheme 1a) as a white solid. This precursor containing two phosphorus-chloride bonds is then reacted with piperidine (in a molar ratio of 1:4, respectively) in CHCl3 at 273 K for 4 h to give compound 1 (scheme 1b).In the 13C NMR spectrum of this compound, three-bond distance coupling with the phosphorus atom is observed for corresponding carbon atoms of piperidine rings (3J(P,C) = 4.7 Hz), but two-bond distance coupling 2J(P,C) not observed. Due to the coupling with both fluorine atoms, each of the three adjacent unsubstituted carbon atoms of the 2,3-F2–C6H3– fragment show the second-order spectra