STUDIES OF POLYHALIDES .27. ON TETRA(N-PR OPYL)AMMONIUM POLYIODIDES (N-PR4N)I-N WITH N=3, 5, 7 - PREPARATION AND CRYSTAL-STRUCTURES OF A TRIIODIDE (N-PR4N)I-3, A PENTAIODIDE (N-PR4N)I-5, AND A HEPTAIODIDE (N-PR4N)I-7

[(n-C3H7)(4)N]I-3, [(n-C3H7)(4)N]I-5 and [(n-C3H7)(4)N]I-7 have been p repared by the reaction of tetra(n-propyl)ammoniumiodide [(n-C3H7)4N]I with iodine It in ethanol. Their crystal structures have been determi ned by single crystal X-ray diffraction methods. The triiodide is buil t up from layers of the quarternary ammonium ions n-Pr4N+ and from two independent differently packed centrosymmetric triiodide ions I-3(-) which alternate with each other along [100]. The pentaiodide ion forms slightly puckered almost squared nets perpendicular [001] of iodide i ons which are connected with four iodine molecules by secondary bonds. The meshes from twelve iodine atoms include the cations. The centrosy mmetric Z-shaped heptaiodide ion is built up from a linear symmetric t riiodide ion and two iodine molecules forming twisted rope ladders alo ng [001] which are separated by stacks of cations.