Raman spectroscopic investigation of N ‐alkylurotropinium polyiodides

N ‐Alkylurotropinium polyiodides, UrRI x , with different iodine contents and different sizes of alkyl group were investigated by Raman spectroscopy. The spectra were recorded for wavenumber shifts up to 500 cm −1 . It was found that the triiodides, UrRI 3 , contain a symmetrical linear I 3 − ion. The pentaiodides, UrRI 5 , contain no triiodide unit; the anion structure can be described as nearly symmetrical, rectangular L‐shaped I 5 − . An interpretation of the Raman spectra of the heptaiodides, UrRI 7 , is that the anion corresponds to an I 5 − . I 2 structure. This is the first proof of such a heptaiodide. A review of previously published data on the Raman spectra of polyiodides is also given.