The ionic title compound, C(12)H(28)P(+)·C(18)HBF(15)O(-), was obtained by the stoichiometric reaction of (t)Bu(3)P, B(C(6)F(5))(3) and water in toluene. A weak P-H⋯O hydrogen bond is observed in the crystal structure.

New ionic amphiphiles with a hexyl-bridged bis(imidazolium) headgroup; Br(-), BF4(-), or Tf2N(-) anions; and a long n-alkyl tail can form thermotropic bicontinuous cubic liquid crystal phases in neat form and/or lyotropic bicontinuous cubic phases with several non-aqueous solvents or water.

Single crystal X-ray diffraction of oxalic acid dihydrate H(2)C(2)O(4).2H(2)O (1), at pressures up to 5.3 GPa, shows significant changes in the molecular geometries, probably accompanied by a proton migration from H(2)C(2)O(4) to H(2)O and formation of ionic species, as predicted by periodic DFT calculations.

The structure of 1-methyl-2-(prop-2-en-1-ylsulfan-yl)-1H-imidazol-3-ium bromide, C7H11N2S(+)·Br(-), has monoclinic (P21/c) symmetry. In the crystal, the components are linked by N-H⋯Br and C-H⋯Br hydrogen bonds. The crystal structure of the title compound undeniably proves that methimazole reacts through the thione tautomer, rather than the thiol tautomer in this system.

The title ionic salt, C21H20P(+)·C24H20B(-), crystallized with two independent vinyl-tri-phenyl-phospho-nium cations and two independent tetra-phenyl-borate anions per asymmetric unit. These four independent moieties contain nearly perfect tetra-hedral symmetry about their respective central C atoms. In the crystal, there are no π-stacking or other inter-molecular inter-actions present.

A new direct-space method for ab initio solution of crystal structures from powder diffraction diagrams is presented. The approach consists of a combined global optimization (`Pareto optimization') of the difference between the calculated and the measured diffraction pattern and of the potential energy of the system. This concept has been tested successfully on a large variety of ionic and inte...