The Spectroscopy and Structure of New 1,3,2-Diazaphospholes and 1,3,2-Diazaphosphorinanes

Abstract

New 1,3,2-diazaphospholes and 1,3,2-diazaphosphorinanes with formula 2,4-Cl₂-C₆H₃-C(O)NHP(O)X where X = (1), (2), (3), and (4) were synthesized and characterized by ¹H, ¹³C, ³¹P NMR, IR spectroscopy, and elemental analysis. The ³¹P NMR spectra revealed that the phosphorus atoms are more deshielded in the diazaphospholes than in the diazaphosphorinanes. The ¹³C NMR spectrum of 2 indicated that ²J_{PC(aliphatic)} = 14.2 Hz for the endocyclic carbon atom is larger than that for the exocyclic CH₃ carbon atom (5.2 Hz). Furthermore, for diazaphosphorinanes, ³J_{PC(aliphatic)} ≈ 2 × ²J_{PC(aliphatic)}. The molecular structure of compound 2 was determined by X-ray crystallography. In this structure, a centrosymmetric dimer is formed via connection of two molecules by strong intermolecular N–HċċċO hydrogen bonds. The presence of weak intermolecular C–HċċċO and C–HċċċCl hydrogen bonds creates a three dimensional polymeric chain in the crystal lattice.

GRAPHICAL ABSTRACT

Keywords:

• 1,3,2-Diazaphosphole
• 1,3,2-diazaphosphorinane
• NMR
• X-ray crystallography
• hydrogen bonds

Acknowledgments

The financial support of this work by the Research Council of Tarbiat Modares University is gratefully acknowledged.