Studies on polyhalides .23. Crystal structures of N-alkylurotropinium triiodides UrRI(3) with R=methyl, ethyl, n-propyl, and n-butyl

The salts UrRI(3) may be prepared by the reaction of N-alkylurotropinium iodides UrRI with iodine I-2 at room temperature from aqueous solution. N-methylurotropinium triiodide C7H15N4I3 crystallizes monoclinically in P2(1)/c with a = 1300.8(2) pm, b = 1276.0(3) pm, c = 859.3(2) pm, beta = 94.75(2) and Z = 4. The crystal struc ture is built up from layers of cations UrMe(+) and of linear symmetric triiodide ions I-3(-) alternating along [100]. N-ethylurotropinium triiodide C8H17N4I3 crystallizes orthorhombically in Pnma with a = 1397.3(5)pm, b = 1221.3(2)pm, c = 886.2(2)pm and 2 = 4. The cationic (UrEt(+)) and anionic (I-3(-)) layers alternate along [010]. N-propylurotropinium triiodide C9H19N4I3 crystallizes monoclinically in P2(1)/c with a = 1885.7(5)pm, b = 1657.1(5)pm, c = 1700.5(4) pm, beta = 112.39(2)degrees and Z = 12. The three independent cations and anions are slightly, but differently distorted. N-butylurotropinium triiodide C10H21N4I3 crystallizes monoclinically in P2(1)/m with a = 991.8(3) pm, b = 757.8(2) pm, c = 1128.2(2) pm, beta = 90.73(2)degrees and Z = 2. The crystal structure is stacked by alternating cationic and anionic layers along [001]. The triiodide ion is asymmetric and linear.