Crystal supramolecularity in 2,2′-iminodipyridinium tetrahalometallate(II) salts: Supramolecular motifs that control tetrahedral halometallate solid state structures

N+–H⋯⋯Br–M and (π)C–H⋯⋯Br–M hydrogen bond synthons have been exploited in the crystallization of a series of 2,2′-iminodipyridinium(2+) dication (hereafter 2,2′-imdipyH2), (C10H11N3)[MX4] salts (M = Co and Hg; X = Cl and Br) and 2,2′-iminodipyridinium(1+) cation (hereafter 2,2′-imdipyH), (C10H10N3)2[MX4] salts (M = Co, Hg; X = Cl and Br). Intermolecular interactions and crystal supramolecularity adopted in these structures were analyzed and compared with reported similar structures, (C10H11N3)[CuCl4] and (C10H10N3)2[CoCl4]. In these salts only one structural form for the halometallate species is observed namely mononuclear tetrahedral. The crystal supramolecularity in the (2,2′-imdipyH2)[MX4] series corresponds to three distinct structural motifs: Parallel ribbons of infinitely connected cyclic dimers of two dications and two anions found in the isomorphous salts of [CoCl4]2− and [CuCl4]2−; and cyclic dimer hearing-bone packing motif found in the isomorphous dication salts of [CoBr4]2− and [HgBr4]2−. Infinitely helical layers based on alternating ⋯⋯anion⋯⋯two stacked cations ⋯⋯anion⋯⋯ two stacked cations⋯⋯ are found in the isomorphous salts of (2,2′-imdipyH)2[CoCl4] and (2,2′-imdipyH)2[HgBr4].

N+–H⋯⋯Br–M and (π)C–H⋯⋯Br–M hydrogen bond synthons control the crystal structure of salts containing 2,2′-iminodipyridinium cation leading to different series of isomorphous salts. The crystal supramolecularity appears in three distinct structural motifs: Parallel ribbons of infinitely connected cyclic dimers of two dications and two anions, cyclic dimer hearing-bone packing motif and infinitely helical layers based on alternating ⋯⋯anion⋯⋯ two stacked cations ⋯⋯anion⋯⋯ two stacked cations in three sets of isomorphous salts.Figure optionsDownload as PowerPoint slideResearch highlights
► Supramolecular entities of mono and dication 2,2′-iminodipyridinium with [MX4]2− anions.
► The cations generate organic–inorganic hybrid solids similar in some cases to those formed by other linear cations as 4,4′-bipyridinium and similar ones.
► N–H⋯⋯X along with complementary C–H⋯⋯X (in some cases) supramolecular synthons are structure determining tools.