STUDIES ON POLYHALIDES, XXXVI - ON THE OCTAIODIDE ION I-8(2-) - PREPARATION AND CRYSTAL-STRUCTURE OF [(CRYPT-2.2.2)H-2]I-8, OF [NI(PHEN)(3)]I-8-CENTER-DOT-2CHCL(3) AND OF THE BIS(N-ALKYLUROTROPINIUM)OCTAIODIDES (URR)(2)I-8 WITH R = METHYL AND ETHYL

The new compound [(Crypt-2.2.2)H-2]I-8 has been prepared by the reacti on of [(Crypt-2.2.2)H-2](I-3)(2) with iodine in methanol. It crystalli zes in the orthorhombic space group Pbcn with a = 11.476 (2), b = 13.5 89 (2), c = 22.888 (2) Angstrom and Z = 4. The crystal structure has b een refined to R-F = 0.031 for 1618 reflections. It may be described a s a layerlike packing of octaiodide anions I-8(2-) and diprotonated 2. 2.2-Crypt as cations. The non planar octaiodide anion is built up from two triiodide groups and a bridging iodine molecule. Tris(1,10-phenan throline)nickel(II) octaiodide bis(chloroform) crystallizes in the mon oclinic space group P2(1)/n with a = 11.683 (8), b = 21.717 (8), c = 2 0.752 (5) Angstrom, beta = 95.03 (5)degrees and Z = 4 formula units. T he crystal structure has been refined to R-F = 0.058 for 3894 reflecti ons. The structure consists of two chloroform molecules, octahedrally coordinated complex cations [Ni(phen)(3)](2+) and nonplanar octaiodide anions I-8(2-) each composed of two asymmetric triiodide units I-3(-) weakly associated with an elongated bridging iodine molecule I-2. The already known structure of bis(N-methylurotropinium) octaiodide, (UrM e)(2)I-8, has been verified and more accurate crystal data have been c ollected. The crystal structure has been refined to R-F = 0.045 for 19 08 reflections. The compound crystallizes in the monoclinic space grou p P2(1)/c with a = 11.302 (2) b = 9.850 (2), c = 14.188 (2) Angstrom, beta = 92.59 (1)degrees and Z = 2. The anion has the shape of a stretc hed Z. The structure of bis(N-ethylurotropinium) octaiodide (UrEt)(2)I -8 has been determined and a new configuration (I-3(-).I-5(-)) for oct aiodide ions between Z (I-3(-).I-2.I-3(-)) and a ''broken'' configurat ion (I-3(-), I-5(-)) has been observed. The compound crystallizes in t he triclinic space group P (1) over bar with a = 9.741 (3), b = 11.815 (3), c = 15.426 (3) Angstrom, alpha = 91.80 (2), beta = 107.14 (2), g amma = 90.04 (2)degrees and Z = 2. The crystal structure has been refi ned to R-F = 0.037 for 3657 reflections.