Polymorphism for a novel phosphoramidate; NMR and X-ray crystallography |
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| Authors: | Khodayar Gholivand Farzaneh Afshar Zahra Shariatinia Karim Zare |
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| Institution: | (1) Department of Chemistry, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran;(2) Department of Biology, Islamic Azad University, Garmsar branch, Garmsar, Iran;(3) Department of Chemistry, Amirkabir University of Technology, P. O. Box 159163-4311, Tehran, Iran;(4) Department of Chemistry, Science and Research Branch, Islamic Azad University (IAU), P.O. Box 14515-775, Tehran, Iran;(5) Department of Chemistry, Shahid Beheshty University, Tehran, Iran |
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| Abstract: | Abstract New phosphoramidates with formula 3-NC5H4C(O)NHP(O)XY (X=Y=Cl (1), X=Y=NH–C(CH3)3 (2a,2b), X=Y=N(C4H9)2 (3), X=Cl, Y=N(C2H5)2 (4) were synthesized and characterized by IR, 1H-, 13C-, 31P-NMR spectroscopy and CHN elemental analysis. Surprisingly, the reaction of compound 2a with LaCl3, 7H2O in 3:1 M ratio leads to a polymorph of this compound (2b). NMR spectra indicate that 2
J(PNHamide) in 2b (7.0 Hz) is very much greater than in 2a (4.1 Hz), while δ(31P) values are identical for both of them. In IR spectra, υ(P=O) is weaker but υ(C=O) is stronger in 2a than in 2b. The structures of 2a, 2b were determined by X-ray crystallography. These compounds form centrosymmetric dimers via two intermolecular P=O……H–N hydrogen
bonds. Strong intermolecular N–H…N, N–H…O and weak C–H…O hydrogen bonds lead to a three-dimensional polymeric cluster in the
2a while intermolecular strong N–H……N and weak C–H……O hydrogen bonds form a two-dimensional polymeric chain in 2b. |
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