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

Abstract

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′-imdipyH 2), (C 10H 11N 3)[MX 4] salts (M = Co and Hg; X = Cl and Br) and 2,2′-iminodipyridinium(1+) cation (hereafter 2,2′-imdipyH), (C 10H 10N 3) 2[MX 4] 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, (C 10H 11N 3)[CuCl 4] and (C 10H 10N 3) 2[CoCl 4]. In these salts only one structural form for the halometallate species is observed namely mononuclear tetrahedral. The crystal supramolecularity in the (2,2′-imdipyH 2)[MX 4] 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 [CoCl 4] 2− and [CuCl 4] 2−; and cyclic dimer hearing-bone packing motif found in the isomorphous dication salts of [CoBr 4] 2− and [HgBr 4] 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[CoCl 4] and (2,2′-imdipyH) 2[HgBr 4].