Phosphorus heterocycles: synthesis, spectroscopic study and X-ray crystallography of some new diazaphosphorinanes

Abstract

New diazaphosphorinanes with formula Open image in new window Open image in new window R=C6H5O (2), 4-CH3-C6H4NH (3), 4-NO2-C6H4NH (4), Open image in new window R=Cl (5), 4-CH3-C6H4O (6), and C6H5NH (7) were synthesized and characterized by 1H, 13C, 31P NMR and IR spectroscopy and elemental analysis. The crystal structures of compounds 1 and Open image in new window (8) were determined using X-ray crystallography. In these structures, the P=O bond is placed in an equatorial position and the aliphatic six-membered rings show chair conformations. These compounds form two-dimensional polymeric chains via intermolecular P=O…H–N hydrogen bonds. 1H NMR spectrum of compound 1 shows a ddd splitting pattern for the coupling of Hequatorial proton with phosphorus atom, Haxial atom, and NH proton with a high-value 3J(PNCH) coupling constant = 26.1 Hz. But, Haxial indicates a dd splitting pattern because of the coupling with Hequatorial and NH protons. 13C NMR spectra of compounds 5–7, indicated high values for 3J(P,C)aromatic = 11.9, 11.3 and 10.2 Hz due to the coupling of the aromatic carbon atom of naphthalene moiety with the phosphorus atom. 31P NMR spectra indicate that the δ(31P) of compounds 1–4 and 8 containing NH groups connected to the aliphatic carbon atoms appear downfield relative to those of compounds 5–7 that containing NH groups connected to the aromatic naphthalene group.