Three isomorphous 2,6-dibromopyridinium tetrabromidometallates: (C(5)H(4)Br(2)N)(2)[MBr(4)].2H(2)O (M = Cu, Cd and Hg).

The structures of three isomorphous compounds, namely bis(2,6-dibromopyridinium) tetrabromidocuprate(II) dihydrate, (C(5)H(4)Br(2)N)(2)[CuBr(4)].2H(2)O, bis(2,6-dibromopyridinium) tetrabromidocadmate(II) dihydrate, (C(5)H(4)Br(2)N)(2)[CdBr(4)].2H(2)O, and bis(2,6-dibromopyridinium) tetrabromidomercurate(II) dihydrate, (C(5)H(4)Br(2)N)(2)[HgBr(4)].

Three-dimensional framework structures: isomorphous bis(2,6-diamino-3,5-dibromopyridinium) tetrabromidometallate(II) salts with Cd(II) and Mn(II).

In the structural motifs of two isomorphous triclinic salts, (C5H6Br2N3)2[MBr4] (M = Cd(II) and Mn(II)), each [MBr4]2- anion interacts with eight surrounding 2,6-diamino-3,5-dibromopyridinium cations through intermolecular C/N-H...

Bis(2,6-diamino-3,5-dibromo-pyridinium) hexa-bromidostannate(IV).

The asymmetric unit of the title compound, (C(5)H(6)Br(2)N(3))(2)[SnBr(6)], contains one cation and one half-anion in which the Sn atom is located on a crystallographic centre of inversion and is in a quasi-octa-hedral geometry. The crystal structure is assembled via hydrogen-bonding inter-actions of two kinds, N(pyridine/amine)-H⋯Br-Sn, along with C-Br⋯Br-Sn interactions [3.4925 (19) Å].

Bis(2,6-dimethyl-pyridinium) tetra-bromido-zincate(II).

In the crystal structure of the title compound, (C(7)H(10)N)(2)[ZnBr(4)], the coordination geometry of the anion is approximately tetra-hedral and a twofold rotation axis passes through the Zn atom. The Zn-Br bond lengths range from 2.400 (2) to 2.

2,5-Dibromo-pyridine.

In the title compound, C(5)H(3)Br(2)N, C-H⋯N hydrogen-bonding inter-actions and Br⋯Br inter-actions [3.9418 (3) and 3.8986 (3) Å] connect the mol-ecules into planar sheets stacked perpendicular to the b axis.

Bis(2-amino-4-methyl-pyridinium) tetra-chloridocuprate(II).

The asymmetric unit of the title compound, (C(6)H(9)N(2))(2)[CuCl(4)], consists of one cation and one half-anion, bis-ected by a twofold rotation axis through the metal center. The anion exhibits a geometry that is inter-mediate between a T(d) and D(4h) arrangement about the Cu atom. The crystal structure contains chains of cations alternating with stacks of anions.

4-(4-Chloro-phen-yl)-1-(2-hydr-oxy-2,2-di-phenyl-acet-yl)thio-semicarbazide.

The asymmetric unit of the title compound, C(21)H(18)ClN(3)O(2)S, contains two mol-ecules in which the bond lengths and angles are almost identical. Intra-molecular N-H⋯S hydrogen bonds result in the formation of two five-membered rings. In the crystal structure, inter-molecular N-H⋯O hydrogen bonds link the mol-ecules into centrosymmetric dimers; these dimers are linked via inter-molecular O-H⋯S hydrogen bonds, leading to infinite corrugated layers parallel to the bc plane through R(2) (2)(16) ring motifs.

3-Ammonio-pyridinium tetra-bromido-mercurate(II) monohydrate.

The asymmetric unit of the title compound, (C(5)H(8)N(2))[HgBr(4)]·H(2)O, consists of one cation, one anion and one water mol-ecule. The anion exhibits a distorted tetra-hedral arrangement about the Hg atom. The crystal structure contains alternating sheets of cations (in the ac plane) and stacks of anions.

Bis(2-bromo-pyridinium) hexa-bromido-stannate(IV).

The asymmetric unit of the title compound, (C(5)H(5)BrN)(2)[SnBr(6)], contains one cation and one half-anion. The [SnBr(6)](2-) anion is located on an inversion center and forms a quasi-regular octa-hedral arrangement. The crystal structure consists of two-dimensional supra-molecular layers assembled via hydrogen-bonding inter-actions of N-H⋯Br-Sn [D⋯A = 3.

Bis-(2-amino-6-methyl-pyridinium) tetra-bromido-cuprate(II).

In the crystal structure of the title compound, (C(6)H(9)N(2))(2)[CuBr(4)], the geometry around the Cu atom is inter-mediate between tetra-hedral (T(d)) and square planar (D(4h)). Each [CuBr(4)](2-) anion is connected non-symmetrically to four surrounding cations through N-H⋯X (pyridine and amine proton) hydrogen bonds, forming chains of the ladder-type running parallel to the crystallographic b axis. These layers are further connected by means of offset face-to-face inter-actions (parallel to the a axis), giving a three-dimensional network.

Bis(2-bromo-pyridinium) hexa-chlorido-stannate(IV).

The asymmetric unit of the title compound, (C(5)H(5)BrN)(2)[SnCl(6)], contains one cation and one half-anion. The [SnCl(6)](2-) anion is located on an inversion center and forms a quasi-regular octa-hedral arrangement. Hydrogen-bonding inter-actions of two kinds, viz.

1,4-Dihydroxy-quinoxaline-2,3(1H,4H)-dione.

The asymmetric unit of the title compound, C(8)H(6)N(2)O(4), contains one half-mol-ecule; a twofold rotation axis bisects the molecule. The quinoxaline ring is planar, which can be attributed to electron delocalization. In the crystal structure, inter-molecular O-H⋯O hydrogen bonds link the mol-ecules into R(2) (2)(10) motifs, leading to layers, which inter-act via phen-yl-phenyl inter-actions (C⋯C distances in the range 3.

Bis(2,6-dimethyl-pyridinium) tetra-bromido-cobaltate(II).

In the crystal structure of the title compound, (C(7)H(10)N)(2)[CoBr(4)], the [CoBr(4)](2-) anion is connected to two cations through N-H⋯Br and H(2)C-H⋯Br hydrogen bonds to form two-dimensional cation-anion-cation layers normal to the crystallographic b axis. Inter-actions of the π-π type are absent between cations in the stacks [centroid-centroid separation = 5.01 (5) Å].

A novel framework of N-H...Br hydrogen bonds forming Br(4,4'-bipyridinium)(4) supramolecular synthons: bis(4,4'-bipyridinium) tris[tetrabromidoferrate(III)] bromide.

In the asymmetric unit of the title compound, (C(10)H(10)N(2))(2)[FeBr(4)](3)Br, the Fe atoms are in a distorted tetrahedral environment. The crystal structure contains a novel arrangement of Br(4,4'-bipyridinium)(4) supramolecular synthons assembled via short N-H..

Bis(2-amino-3,5-dibromo-4,6-dimethylpyridinium) hexabromidostannate(IV).

In the title compound, (C(7)H(9)Br(2)N(2))(2)[SnBr(6)], the cations and centrosymmetric anions are stacked in alternating layers that show no significant intermolecular interactions within each stack. Extensive cation..