Exploring the Structural Chemistry of Pyrophosphoramides: N,N′,N″,N″′-Tetraisopropylpyrophosphoramide

• Main Authors: Duncan Micallef, Liana Vella-Zarb, Ulrich Baisch
• Format: Article
• Language: English
• Published: MDPI AG 2021-01-01
• Series: Chemistry
• Subjects: N,N,’N’’,N’’’-Tetraisopropylpyrophosphoramide; pyrophosphoramide; synthons; supramolecular motifs; X-ray crystallography
• Online Access: https://www.mdpi.com/2624-8549/3/1/13

N,N′,N″,N″′-Tetraisopropylpyrophosphoramide <b>1</b> is a pyrophosphoramide with documented butyrylcholinesterase inhibition, a property shared with the more widely studied octamethylphosphoramide (Schradan). Unlike Schradan, <b>1</b> is a solid at room temperature making it one of a few known pyrophosphoramide solids. The crystal structure of <b>1</b> was determined by single-crystal X-ray diffraction and compared with that of other previously described solid pyrophosphoramides. The pyrophosphoramide discussed in this study was synthesised by reacting iso-propyl amine with pyrophosphoryl tetrachloride under anhydrous conditions. A unique supramolecular motif was observed when compared with previously published pyrophosphoramide structures having two different intermolecular hydrogen bonding synthons. Furthermore, the potential of a wider variety of supramolecular structures in which similar pyrophosphoramides can crystallise was recognised. Proton (¹H) and Phosphorus 31 (³¹P) Nuclear Magnetic Resonance (NMR) spectroscopy, infrared (IR) spectroscopy, mass spectrometry (MS) were carried out to complete the analysis of the compound.