1,1,2,2-Tetra-kis(1,3-benzoxazol-2-yl)ethene.

The title compound, C(30)H(16)N(4)O(4), reveals [Formula: see text] crystallographic and mol-ecular symmetry and accordingly the asymmetric unit comprises one half-mol-ecule. The dihedral angle between the planes of the two geminal benzoxazole rings is 74.39 (5)°.

1,1,2,2-Tetra-kis(1,3-benzothia-zol-2-yl)ethene chloro-form disolvate.

The asymmetric unit of the title solvate, C(30)H(16)N(4)S(4)·2CHCl(3), contains one half-molecule of tetrakis(2-benzothiazolyl)ethene, the complete molecule being generated by inversion symmetry, and one molecule of chloroform. Pairs of the benzothia-zole rings attached to the same carbon atom are almost perpendicular to each other, with an angle between planes of 85.74 (4)°.

1,3-Benzothia-zolium tetra-chlorido-aurate(III) tetra-hydro-furan solvate.

In the crystal structure of the title ionic compound (C(7)H(6)NS)[AuCl(4)]·C(4)H(8)O, the [AuCl(4)](-) anion shows a typical square-planar geometry. Numerous weak C-H⋯Cl hydrogen bonds between [AuCl(4)](-) and the 1,3-benzothia-zolium units form layers comprised of 24-membered rings in which hydrogen-bonded tetra-hydro-furan (THF) solvent mol-ecules are accommodated. C-H⋯Cl inter-actions between THF and [AuCl(4)](-) from adjacent layers result in bilayers.

1,3-Dimesitylimidazolidinium tetra-chloridogold(III) dichloro-methane solvate.

The title ionic compound, (C(21)H(27)N(2))[AuCl(4)]·CH(2)Cl(2), was obtained from the reaction of 1,3-dimesitylimidazolidinium chloride with t-BuOK and a solution of AuCl(3) in tetra-hydro-furan. In the crystal structure, numerous weak C-H⋯Cl hydrogen bonds form double layers parallel to (100), which are further stabilized by π-π inter-actions between mesitylene rings [centroid-centroid distance = 4.308 (4) Å], resulting in the formation of a three-dimensional supra-molecular assembly.