Cavallo Gabriella, Metrangolo Pierangelo, Pilati Tullio, Resnati Giuseppe, Terraneo Giancarlo
NFMLab, Department of Chemistry, Materials and Chemical Engineering, "Giulio Natta", Politecnico di Milano, Via Mancinelli, 7, I-20131 Milano, Italy.
Acta Crystallogr Sect E Struct Rep Online. 2013 May 11;69(Pt 6):o865-6. doi: 10.1107/S1600536813012397. Print 2013 Jun 1.
The crystallization of a 1:1 molar solution of 1,3,5-tri-fluoro-2,4,6-di-iodo-benzene (TFTIB) and tetra-phenyl-phosponium iodide (TPPI) from methanol produced tetra-gonal needles of pure TPPI and tabular pseudo-hexa-gonal truncated bipyramids of the title compound, 3C24H20P(+)·3I(-)·4C6F3I3·CH4O or (TPPI)3(TFTIB)4·MeOH. The asymmetric unit is composed of six TPPI mol-ecules, eight TFTIB mol-ecules and two methanol mol-ecules, overall 16 constituents. The formation of the architecture is essentially guided by a number of C-I⋯I(-) halogen bonds (XB), whose lengths are in the range 3.276 (1)-3.625 (1) Å. Layers of supra-molecular polyanions are formed parallel to (10-1) wherein iodide anions function as penta-, tetra- or bidentate XB acceptors. The structure is not far from being P21/n, but the centrosymmetry is lost due to a different conformation of a single couple of cations and the small asymmetry in the formed supra-molecular anion. One methanol mol-ecule is hydrogen bonded to an iodide anion, while the second is linked to the first one via an O-H⋯O contact. This second methanol mol-ecule is more loosely pinned in its position than the first and presents very high anisotropic displacement parameters and a seeming shortening of the C-O bond length. The crystal studied was refined as a perfect inversion twin.
1,3,5 - 三氟 - 2,4,6 - 二碘苯（TFTIB）与四苯基碘化鏻（TPPI）的1:1摩尔溶液在甲醇中结晶，生成了纯TPPI的四方针状晶体以及标题化合物3C₂₄H₂₀P⁺·3I⁻·4C₆F₃I₃·CH₄O或(TPPI)₃(TFTIB)₄·MeOH的片状假六方截顶双锥体晶体。不对称单元由六个TPPI分子、八个TFTIB分子和两个甲醇分子组成，总共16个组分。该结构的形成主要受一些C - I⋯I⁻卤键（XB）的引导，其键长范围为3.276 (1) - 3.625 (1) Å。超分子聚阴离子层平行于(10 - 1)面形成，其中碘离子作为五齿、四齿或双齿XB受体。该结构与P21/n结构相差不大，但由于一对阳离子的不同构象以及所形成的超分子阴离子中的小不对称性，中心对称性丧失。一个甲醇分子通过氢键与一个碘离子相连，而第二个甲醇分子通过O - H⋯O接触与第一个相连。第二个甲醇分子在其位置上比第一个更松散地固定，呈现出非常高的各向异性位移参数以及C - O键长的明显缩短。所研究的晶体被精修为一个完美的倒易孪晶。
