Halogen impact into new oxonium benzo-crown ether complexes with tetrachloro- and tetrabromoaurates(iii)

Abstract

Five oxonium tetrahalogenaurate(III) (Hal = Cl, Br) benzo-crown ether (BCE) complexes are prepared and reported. The new compounds are [(H3O)(B18C6)(0.58)(4'-Cl-B18C6)0.42][AuCl4] 1, [(H3O)(B18C6)][AuCl4] 2, [(H3O)(4'-Br-B18C6)][AuCl4] 3, [(H3O)(4'-Br-B18C6)][AuBr4] 4, and [(H3O)(B18C6)][AuBr4] 5. The reaction medium, distinctive from the previously used aqua regia, allowed avoiding the unwanted nitration of initial macrocycles. The compositions and structures for 1, 3, 4, and 5 were proved by single crystal X-ray crystallography. The complete conversion of tetrachloroaurate(III) to the tetrabromoaurate(III) salts resulted in complex 4 isomorphous and isostructural to 3. All compounds form the laminated structures with alternation of cationic and anionic layers. The robustness of the anionic sheets is sustained by the halogen-halogen interactions and makes crucial impact on extraction of stoichiometric products in the case of tetrabromoaurate(III) salts.

Halogen Bonding in Supramolecular Chemistry

“…A recent pioneering study with more precious metals described the impact of XB interactions in the stabilization of new benzo crown ether tetrahaloaurate­(III) (Cl or Br) complexes (Figure ). All structures obtained exhibited laminated structures of alternating anionic and cationic layers, with the anionic tetrahaloaurate 2D sheets propagated by halogen–halogen close contacts. It was also evident that the tetrabromoaurate structures could be obtained from the benzo crown ether and HAuCl 4 in HBr solution via in situ halogen exchange, resulting in a structure that was isomorphous and isostructural with the tetrachloroaurate structure.…”

“…Crystal structures of tetrahaloaurate complexes showing intralayer halogen bonds: (a) [(H 3 O)­(B18C6) 0.58 (4′-Cl-B18C6) 0.42 ]­[AuCl 4 ] (CSD Refcode QOCVUB), (b) [(H 3 O)­(4′-Br-B18C6)]­[AuCl 4 ] (CSD Refcode QOCWAI), (c) [(H 3 O)­(4′-Br-B18C6)]­[AuBr 4 ] (CSD Refcode QOCXIR), and (d) [(H 3 O)­(B18C6)]­[AuBr 4 ] (CSD Refcode QOCXOX). …”

Crystal structure of metronidazolium tetrachloridoaurate(III)

“…Metronidazolium derivatives that feature other counter-ions, e.g. 3-carboxy-4-hydroxybenzenesulfonate and perchlorate have been reported (Yang, 2008;Wang et al, 2010), as have a variety of tetrachloridoaurate(III) complexes (Johnson & Steed, 1998;Pluzhnik-Gladyr et al, 2014;Fazaeli et al, 2010). The asymmetric unit of the title compound, shown with 20% probability displacement ellipsoids.…”

Transformations of Benzo-15-Crown-5, [3.3]DIBENZO-18-CROWN-6 and [4.4]DIBENZO-24-CROWN-8 in Aqueous Solutions of Nitric Acid

“…Причем, в концентрированных растворах последней образуются её комплексы не с исходными КЭ, а с продуктами их нитрования (в случае I и III) или хлорирования (в случае II). Аналогичное мы наблюдали при взаимодей-ствии Б18К6 с раствором ЗХВК в ЦВ [18] − в ряде случаев образовывалась смесь гидроксониевых комплексов ЗХВК с исходным БКЭ и продуктом его хлорирова-ния 4'-хлор-Б18К6. Было высказано предположение, что в подобных случаях хло-рид золота(III), как кислота Льюиса, может играть ключевую роль в хлорировании БКЭ и ДБКЭ.…”