Investigation of Phosphazene Superbase Interactions with [PClN].

In this study, the reaction between phosphazene superbases and a chlorophosphazene trimer ([PClN]) has been investigated. In this room temperature reaction, the phosphazene superbase (MeN)PN(MeN)P═NEt, commonly known as PEt, was shown to behave as a nucleophile, displacing one of the chlorides from [PClN] and producing the tadpole-like structure . The reaction described herein is one of the few instances of a phosphazene superbase behaving as a nucleophile rather than a Brønsted base. Once formed, this structure contains contrasting reactivity, containing a weakly basic phosphazene head while maintaining a highly basic phosphazene tail of the tadpole. The mechanism of the reaction was explored by investigating the potential energy surface through density functional theory calculations at the B3LYP/6-311+G(d,p) level of quantum mechanical theory. It was determined that the reaction of PEt with [PClN] followed a stepwise process beginning with the substitution of PEt onto [PClN] with the concurrent loss of chloride. Subsequently, the chloride attacks the ethyl group of the PEt moiety, and ethyl chloride is released, producing . Compound was further characterized via P NMR spectroscopy, mass spectrometry, and X-ray crystallography.