A new protonation chemistry of phosphazenes and the formation of bis(sulfonyl)imides

The protonation of N-sulfonyl trichlorophosphazenes (R¹-N=PCl₃) with sulfonic acids has been successfully utilized as a facile synthesis route for bis(sulfonyl)imides. It was also found that the formation of protonated imides is strongly affected by the acid strength of the proton donors and the N-substituents (R¹). When R¹ is a good leaving group, a hitherto unobserved protonation chemistry occurs, producing a series of mixed sulfonylphosphonylimides. A tentative rationale is proposed for the novel chemistry of phosphazenes.