Halobismuth(III) salts with substituted aminopyridinium cations

The crystal structures of six halobismuth(III) salts of variously substituted aminopyridinium cations display discrete mononuclear [BiCl₆]^3- and dinuclear [Bi₂X₁₀]^4- anions (X = Cl or Br), and polymeric cis-double-halo-bridged [Bi_nX_4n]^n- anionic chains (X = Br or I). Bis(2-amino-3-ammoniopyridinium) hexachloridobismuth(III) chloride monohydrate, (C₅H₉N₃)₂[BiCl₆]Cl·H₂O, (1), contains discrete mononuclear [BiCl₆]^3- and chloride anions. Tetrakis(2-amino-3-methylpyridinium) di-μ-chlorido-bis[tetrachloridobismuth(III)], (C₆H₉N₂)₄[Bi₂Cl₁₀], (2), tetrakis(2-amino-3-methylpyridinium) di-μ-bromido-bis[tetrabromidobismuth(III)], (C₆H₉N₂)₄[Bi₂Br₁₀], (3), and bis(4-amino-3-ammoniopyridinium) di-μ-chlorido-bis[tetrachloridobismuth(III)] dihydrate, (C₅H₉N₃)₂[Bi₂Cl₁₀]·2H₂O, (4), incorporate discrete [Bi₂X₁₀]^4- anions (X = Cl or Br), while catena-poly[2,6-diaminopyridinium [[cis-diiodidobismuth(III)]-di-μ-iodido]], {(C₅H₈N₃)[BiI₄]}_n, (5), and catena-poly[2,6-diaminopyridinium [[cis-dibromidobismuth(III)]-di-μ-bromido]], {(C₅H₇N₂)[BiBr₄]}_n, (6), include [Bi_nX_4n]^n- anionic chains (X = Br or I). Structures (2) and (3) are isostructural, while that of (5) is a pseudomerohedral twin. There is no discernible correlation between the type of anionic species obtained and the cation or halide ligand used. The Bi^III centres always have a slightly distorted octahedral geometry and there is a correlation between the Bi-X bond lengths and the number of classic N-H...X hydrogen bonds that the X ligand accepts, with a greater number of interactions corresponding with slightly longer Bi-X distances. The supramolecular networks formed by classic N-H...X hydrogen bonds include ladders, bilayers and three-dimensional frameworks.